ON THE ACTION OF SOME OF THE MORE IMPORTANT MEDICINES IN PARTICULAR.

The chief objects for which I have designed this Fourth Chapter are that I may be enabled to illustrate some general principles of the action of medicines which have been laid down in the Propositions, and show in what manner they are applicable to special cases,—and to enter into certain details respecting the more important remedies, which have not been attempted as yet. Of many of these medicines a tolerably full account has already been given; but they may again be mentioned here for the purpose of shortly summing up their several actions, and comparing them one with another.

It often happens that there is more than one point of view from which the action of a medicine may be regarded. For many medicines are numbered under several distinct heads, being included in different groups on account of the several phases of their operation. There are three stages in the progress of the remedy through the system, at each of which it may exert a special action. There is a contact with the surface; a continuance in the system; and a passage out of the system. In the first place a medicine touches the mucous surface of the alimentary canal; here some few evidence their action. From this, if in any way soluble, it passes into the blood. Here it may act on the blood, being HÆmatic. Or it may employ the blood merely as a means of transit, and direct itself towards nerve or muscular fibre, being Neurotic or Astringent. But we have seen that none of these medicines, with the only exception of Restorative HÆmatics, can remain long in the system. They must pass out, and the mode of passage is through the glands. Here is a third opportunity of operation. The medicine may act now as an Eliminative, increasing the secretion of the gland; or, more rarely, as a glandular Astringent, because tending to diminish it.

As a general rule, though not in all cases, the most important action of a medicine is that which it first evidences, the subsequent operations being secondary, and of less moment. Thus Mercury is, in the first place, a Catalytic HÆmatic; in the second place, an Eliminative. Creosote is firstly a general Sedative, secondly an Astringent. Antimony probably belongs to three out of the four classes, and its second operation is perhaps the most important. It is a Catalytic, a special Sedative, and also an Eliminative.

COD-LIVER OIL.

Class I. Div. I. Ord. I. Alimenta.

This oil has been proved by the experience of many physicians to be a medicine of great utility in most cases in which there is a general deficiency of fat in the system. It is thought also to exert a specific action in the cure of pulmonary Phthisis, and it certainly appears to be the only medicine that possesses any marked or peculiar power over the progress of this disorder. When administered in favourable cases it seems not only to have the power of fattening the patient, but to be able also to combat and cure the disease itself, arresting or retarding the tubercular deposit. Sometimes it is unable to do this; but in all cases of consumption a trial should at least be given to it. It is of most service when the disease is only incipient, and, if given in the first stage, may often prevent its further progress; but it may even cure patients in whom the deposit has passed the stage of softening, as appears from the reports of the Brompton Hospital.

It is also of use in Scrofula, in chronic Rheumatism, and in cases of emaciation generally. It may prove nutritive in Diabetes mellitus, because it is not likely to be converted into sugar in the system, whereas in that disorder all kinds of food, excepting fats and oils, are liable to this change. Cod-liver oil is assimilated to the tissues, and there seems to be something in it which not only renders it more easy to assimilate than other oils, but which further endows it with a special influence over tuberculous diseases. It does not appear that any other oils are equally effective. Though Dr. Duncan and Mr. Nunn have recommended Almond-oil instead of Cod-liver oil, yet the general experience of others is decidedly against such a substitution.

It has not yet been clearly ascertained to which of the constituents of this oil its valuable properties are owing. Being itself an animal product, it is for that reason more easy of assimilation than a vegetable oil. Many have attributed its virtues to Iodine, of which, according to De Jongh, it contains 29 parts in 100,000.

Dr. Theophilus Thompson has tried both Olive and Almond oils in consumptive cases, but has not found that any material benefit is derived from their use. He considers that Cod-oil produces its best effects in cases where Iodine would be inadmissible. Neither does he think its virtue to be due to the biliary matters which it contains, for a mixture of ox-gall with Almond-oil does not supply its place. Cod-oil contains 7½ parts in 100,000 of Phosphorus. Dr. Thompson supposes that its efficacy may be partly owing to this. He has made trial of Phosphuretted Almond-oil, containing one grain of Phosphorus to the pint. He suggests that this Phosphorus may be of use in diverting some of the Oxygen from the tissues. This is to adopt Liebig's theory of the excess of Oxygen in Phthisis; an idea which is not very consistent with the experiments of Dr. Hutchinson on his Spirometer, from which it appears that the quantity of air inhaled at each breath by a consumptive patient is considerably less than in health, on account of a diminished capacity of the lungs. But when a continual fever has set in, an oxidation and waste of the tissues must certainly take place. (Lancet, October, 1851.)

The Phosphorus in Cod-liver oil would soon be oxidized, and it would seem to be too small in amount to be of service in this way. If any thing were thus needed as a pabulum for Oxygen, we might suppose it to be the oil itself that was thus burnt.

Possibly the utility of this medicine may depend upon a combination of several constituents and various properties. It is an oil; and thus of use as an Aliment, and as a supporter of the respiratory function. It is an animal oil; and thus peculiarly adapted for being digested, absorbed and assimilated to the adipose tissues of the human body. It contains Iodine and Bromine, which are useful as Alteratives or blood medicines, both in Phthisis and Scrofula. Their proportion will not seem so small when the large dose of the oil and its frequent repetition are taken into account. But their presence alone would not be sufficient to explain the utility of the oil. It contains also Phosphorus, a general Stimulant, which may prove of use when there is a failure of the nervous forces.

Sometimes the dose of the oil excites a most distressing nausea. This may perhaps be prevented by a judicious modification of the vehicle. It may be floated on an aromatic water, on a bitter infusion, on milk, on wine, or on cold tea, to suit various tastes. In other instances the dose is swallowed without inconvenience, but the patient is not fattened, nor is his condition in the least improved by it. In such incurable conditions it is probable that there is often an organic disease of the Pancreas, or a failure in the function of that gland. For it appears that the absorption of fats is effected by means of an alkali contained in the Pancreatic fluid. When there is reason to suspect this cause of the emaciation, it is advisable to saponify the oil by shaking it with a sufficient quantity of solution of Potash or of Carbonate of Soda. The dose will then be in a state of solution, and ready for absorption.

Cod-liver oil may be used with advantage as a vehicle for Iodide of Iron, in scrofulous cases. Two grains of this may be dissolved in each ounce of the oil. (Vide pp. 119, 191, 229.[47])

SULPHURIC ACID.

Class I. Div. I. Ord. II. Acida.

Class III. Ord. I. Astringentia Mineralia.

This medicine acts chemically as an acid in the blood and in the secretions. When diluted it is easily absorbed, and meeting in the stomach with an acid secretion, it passes into the circulation without being first neutralized. If in small quantity, it is neutralized by the slight excess of alkali in the blood; if in larger amount, it may exceed this alkali, and displace and set free other acids in the blood, combining with their bases on account of its strong affinities. In all cases it increases the quantity of free acid in the system, and tends to render the secretions, as the urine, more acid than they were before. (Vide Dr. Bence Jones's Animal Chemistry, p. 49.)

By this chemical action Sulphuric Acid is rendered useful in alkalinity of the blood, which may occur in fevers; or of the urine, as in Phosphaturia. It thus acts as a Restorative HÆmatic. But it is not right that there should be more than a certain quantity of this acid in the system. So that when introduced in large quantity it must be excreted. It does not appear that it is itself excreted in the urine, though it may cause an excess of other acids in that secretion. On this point Dr. Bence Jones has made some careful experiments. (Anim. Chem., p. 75.) He finds that Sulphuric Acid does not pass off in the urine, either free or in combination, except when given in great quantity. Now it is found that Sulphuric Acid is of great use as an Astringent in diarrhoea. Placing these two facts in juxtaposition, it would seem that the acid, which is doubtless absorbed in the first place, must afterwards be eliminated from the system by the surface of the bowels. This is perhaps because the secretion of this mucous membrane is the one which is least likely to be deranged by the presence of the acid.

The free acid is an Astringent, and has the power of coagulating albumen, and causing the contraction of muscular fibre. (P. 256.) Though probably neutralized and combined while in the blood, it is free before absorption, and after excretion. Before absorption it is an Astringent to the surface of the stomach; after and during excretion, to the surface of the bowels. It is useful chemically in alkaline Pyrosis. Its astringent property explains its utility in acid dyspepsia, which appears at first sight incomprehensible. Lactic acid, or some similar acid, is poured out in excess by the glands of the stomach. Sulphuric acid topically constringes the muscular fibre of the ducts of these glands, and in this way diminishes their secretion.

The acid, if in excess in the blood, may tend to brace the system by causing a general contraction of the fibres of the voluntary muscles. But it is chiefly on account of its anti-dyspeptic agency, and its astringent action on the secretions, that the title of Tonic has been so often applied to it.

Next to that of the bowels, the acid appears to act most on the secretion of the skin. Probably there also eliminated in a free state, it is thus able to diminish excessive diaphoresis.

It is applicable in cases of HÆmorrhage, when this takes place from a mucous membrane, for it probably passes off in small quantities from all the mucous surfaces. It is very useful in diarrhoea. (Vide p. 294.) Being a special Astringent to the intestinal mucous surface, it may possibly be useful even in malignant cholera, especially if given in the early stage of that disorder. (Vide pp. 120, 154, 262.)

POTASH.

Class I. Div. I. Ord. III. Alkalia.

Class I. Div. II. Ord. I. Antiphlogistica.

Class I. Div. II. Ord. III. Antiscrofulosa.

Class IV. Ord. VI. Diuretica.

Potash is one of those medicines which have several distinct actions; but its various operations are comparatively simple in nature, and easy to comprehend. In the solid state it is powerfully caustic and corrosive, having a great affinity for water, and abstracting it from the animal tissues with which it is brought in contact.

When a dose of the solution, properly diluted with water, is administered internally, it passes first into the stomach, and either combines with the acid of the gastric juice, or, what is more probable, it becomes absorbed too rapidly to be neutralized by it. It passes then into the blood, and probably exists in that liquid in a free state, for the blood already contains a slight excess of alkali. However this may be, it certainly increases the amount of alkali in the system.

Its hÆmatic action depends in great part on its power of neutralizing acidity. It is thus useful in cases of acid dyspepsia, heartburn, or gastrodynia, when it combines with the excess of acid which exists in the gastric secretion, and probably also in the blood. For the same reason it is useful in some cutaneous diseases that are connected with disordered digestion. It is employed in Gout and Rheumatism, where there is obviously an excess of acid both in the blood and in the secretions. (P. 202.)

When Potash, is administered in any quantity, it must be excreted from the blood. The secretion of alkalies is mainly performed by the kidneys, and by their agency we may render the urine neutral or alkaline, and thus counteract a tendency to lithic deposits. (Vide Solvents.) For this purpose Potash is preferable to free Soda, for the lithate of Soda is comparatively an insoluble salt.

The salts of Potash with vegetable acids change into carbonates while in the blood, and will render the urine alkaline. M. WÖhler, who has discovered this fact, finds that it does not occur with the super-salts. Even the neutral salts escape the oxidation when they are given in such large doses as to act on the bowels.

Potash is thus a Restorative HÆmatic, and where, from any reason, alkaline matter is needed in the system, it directly supplies the want. But it has also other actions which render it Catalytic, and which are evidenced in disorders in which there is no such deficiency of alkali. By dissolving Fibrine, it tends to prevent its deposition from the blood. It thus interferes with the inflammatory process, and acts as a general Antiphlogistic. It is possibly by a similar action that it seems able to counteract the deposit of crude tubercle, and exerts a special action in the prevention and cure of strumous disorders. It is very useful in the early stage of Phthisis, and in all stages of Scrofula. In Syphilis, when occurring in scrofulous subjects, Potash has sometimes been used with greater advantage than Mercury.

Potash and its salts have been used in Scurvy by Dr. Garrod, on the supposition that there is in that disorder a particular deficiency of Potash in the system. But the fact that Citric acid is at least of equal utility in the treatment of scorbutic diseases, would seem to be opposed to such an idea. When given in moderate doses, and not retained in the system, Potash and its salts pass out into the urine, and act as Diuretics. (Vide pp. 126, 187, 193, 202, 206.)

QUININE.

Class I. Div. I. Ord. IV. Tonica.

Though the utility of this important remedy is often of a sufficiently direct and obvious character, its precise mode of action is enveloped in no small degree of doubt and obscurity. This subject has been discussed at some length in the article on Tonics.

It appears, from the character and results of its medicinal influence, that it is exerted primarily in the blood, and not on the nerves. It is included in the Restorative group of HÆmatics, and the general results of its action differ widely from those of a Catalytic HÆmatic. It produces no marked effect upon the system in health. Its operation consists in the cure of general debility, however produced, and in the prevention of periodic disorders in the blood. Debility depends on a want in the blood, and not on any active morbid process; and there are circumstances which render it likely that Ague may be curable by the supply of a similar want.

Quinine is also serviceable in Gout, Scrofula, Dyspepsia, and other disorders; in all of which other medicines, which stimulate the secretion of the bile, are more or less applicable. Torpidity of the liver is likewise a usual accompaniment of the various forms of debility, and occurs in intermittent, remittent, typhoid, and yellow fevers; in each of which this medicine has been recommended, and used with advantage. In fact it may be said, that in all diseases in which Quinine is used there is a failure in the secretion of bile; and in all diseases in which there is a failure in the secretion of bile, Quinine is serviceable.

There appears then to be some connexion between these two things. Certain of the constituents of the bile are formed by the liver out of the blood, for the purpose, apparently, of being again absorbed at some part of the surface of the intestinal canal. One of these, Taurine, has been shown to be chemically analogous to Quinine. Thus it seems to me to be not improbable that this alkaloid may be of service in these disorders by supplying the place in the blood of this biliary matter, which for some reason may be needful in the animal economy, or that it may actually become changed into the latter while in the system. Were this proved, its restorative action would be effectually cleared up.

The Disulphate of Quinine (or Quina) is the preparation of the alkaloid which is most commonly used.

Arsenic is used in Ague and intermittent disorders, and acts on the Catalytic principle, but it is not serviceable in the other cases in which Quinine is used. It is not a Tonic, nor does it seem to have any relation to the function of the liver. I have thought it advisable to restrict the term Antiperiodic to the Catalytics which are used in Ague. (Vide p. 141.) Quinine and Arsenic may both be employed in all disorders which put on an intermittent or periodic type. The chief of these is Ague, or Intermittent Fever. It is perhaps easier to arrest the disorder by Quinine than by Arsenic; for Quinine may be given in large doses, which cannot be done with Arsenic. But the administration of the latter may be continued during the paroxysm, when the great febrile reaction forbids the use of the other. The dose of Quinine is apt to disagree with an irritable stomach, and to increase the fever. It is generally laid down that this remedy should not be administered when there is a quick hard pulse, or heat and dryness of the skin. Some, however, have lately ventured to prescribe it to patients in high fever. It appears that there is a particular class of patients which in such cases will bear the administration of Quinine with impunity; while others are unfavourably affected by the smallest dose.

It is perhaps at all times advisable to arrange so that the medicine shall, if possible, be taken after meals, for it is less likely to irritate a full stomach. And when it is thought proper to give it to a patient in fever, a small dose of Tartar Emetic or Ipecacuanha should be conjoined with it—not, of course, sufficient to produce vomiting, but so that an increase of the febrile excitement may be prevented.

Quinine is in all cases better tolerated by the stomach when the dose is considerably diluted with water.

A combination of Quinine and Iron is often of great service in feeble and relaxed conditions, where there is co-existent AnÆmia. (Vide p. 129.)

IRON.

Class I. Div. I. Ord. V. Chalybeata.

It has been shown, in the article on Chalybeates, that the action of Iron is of a distinctly Restorative nature.

There is in the blood a red colouring matter, called HÆmatosin. It is found by chemical analysis that Iron is an essential part of this substance. The existence of the right amount of HÆmatosin in the blood is of vital importance. It is contained in the red globules of the blood. When it is diminished in quantity, the number of these red globules is lessened in the same proportion. This produces a paleness of all the tissues, an inactivity of the muscular fibre, an impairment of all the animal functions, and a general languor and debility of the whole frame. This is AnÆmia.

In all cases in which Iron is used there is a deficiency of this red colouring matter; and in all instances of AnÆmia Iron is appropriate as a remedy. The blood has been analyzed before its use, and found to contain a smaller quantity of HÆmatosin and fewer red globules than in health. After its employment the blood has been analyzed again, and it is found that the amount of HÆmatosin and of red globules is increased.

Iron, then, is given in AnÆmia. It is also given in cases of Scrofula, Cancer, Chorea, Hysteria, and other disorders, when these are attended with AnÆmia. When this last condition is wanting, it seldom proves efficacious.

Iron, when given in moderate doses, remains in the system, and enters into the composition of the blood. It is then a Restorative HÆmatic.

Some of the salts of Iron are also Astringent. Thus the Sulphate and Sesquichloride may, by their topical action on the stomach, be of service in cases of atonic Dyspepsia.

In AnÆmia produced by special causes, as by scrofulous or nervous disorder, we may often do most good by striking at the root of the evil,—employing a Catalytic medicine which shall be able to do this. In simple AnÆmia, Iron is of more use than any other medicine. It should be combined with exercise, air, light, and good living. In other disorders a combination of drugs is frequently of use. In chronic Ague, and in many cases of debility, Iron and Bark may be given together. Iron and Aloetic purges may be prescribed in Chlorosis and Amenorrhoea. A mild purgative should be occasionally given in all cases in which Iron is used. The Ammonio-citrate of Iron,—the compound Iron mixture, which contains the Carbonate,—and the Tincture of the Sesquichloride,—are perhaps the best of the officinal Chalybeate preparations. The first of these is the mildest, and the last the most irritant of the three. (Vide pp. 145, 263.)

ANTIMONY.

Class I. Div. II. Ord. I. Antiphlogistica.

Class II. Div. III. Ord. II. Sedantia Specifica.

Class IV. Ord. II. Expectorantia.

Class IV. Ord. V. Diaphoretica.

The best Antimonial for general purposes, and the most characteristic in its mode of operation, is Tartar Emetic. In this medicine are exhibited three distinct varieties of action. The first of the terms which are applied to it above implies that it has a Catalytic action in the blood. As a Special Sedative, it is able to cause nausea and vomiting. And it acts upon the glands as an Eliminative; being a Diaphoretic and an Expectorant.

I have found it convenient to restrict the term Antiphlogistic to those medicines which counteract the inflammatory process by an action in the blood. In this sense it is applicable to Antimony; although this medicine is still better able to subdue inflammation by its powerful neurotic action.

The operation in the blood is naturally slower than the action on nerve, and is therefore less marked, and less immediately applicable. Antimony deteriorates and impoverishes the blood in very much the same way as Mercury, and, if given in small and carefully regulated doses, is simply a mild Antiphlogistic and Eliminative. It tends to increase all secretions, but particularly the exhalation from the skin and lungs, independently of the production of nausea (P. 324,) a symptom which is not brought on by a small dose. It is probable that a diaphoretic dose of Tartar Emetic is actually eliminated from the skin and mucous membranes. Antimony is appropriate as a Diaphoretic in high fevers, and in cases where Opium could hardly be used. But Opium is preferable in cases where there is gastric irritation, and a weak compressible pulse.

The action by virtue of which Antimony has gained its high reputation as a medicine is of a different kind. By an influence on a part of the nervous system, apparently the Vagus nerve, it produces first the state called nausea, and afterwards vomiting. The most important symptom in this nausea, and in the state of system which succeeds the vomiting, and continues for some time after it, is a depression of the action of the heart. At the same time the muscular system is relaxed, and the breathing is rendered slower.

This nausea is not produced to any extent by a mere irritant Emetic, such as Sulphate of Zinc, which acts externally and takes effect immediately. The Antimonial cannot act so quickly; part of it must first be absorbed, so that it may reach the nerve. We know that it does not act by outward irritation, from the fact that if the solution be injected into the veins at any part of the body, it will equally produce nausea and vomiting. Antimony has no direct action upon the brain; it affects only a part of the nervous system. In the nausea we recognise a sedative action upon the nerves of the heart; and in the slow breathing a similar action upon the nerves of the lungs. But it may be objected that the production of vomiting is not a sedative action, for we know that the same symptom may be caused by a mere external stimulant. And yet there are several reasons which have induced me to conclude that this also is a sedative action. It would be inconsistent to suppose that Antimony could be a Sedative in producing nausea, and a Stimulant in causing vomiting. We have already noticed that a Sedative medicine may affect nervous force in either of two ways; it may derange it, or it may depress it. (P. 243.) That influence which causes the contraction of the stomach to commence at the pylorus, and to result in the expulsion of its contents upwards along the oesophagus, is obviously explained by an action of derangement, for it is an exact reversal of the natural state of things. (P. 92.) But the effects of derangement are often very similar to those of excitation. Thus convulsions of the muscular system are caused by Hydrocyanic acid, a Sedative,—and by Strychnia, a Stimulant; and vomiting is producible by Tartar Emetic, a Sedative,—or by an external irritant of the mucous membrane.

It is by the production of nausea that Antimony becomes so valuable an agent in the control of high fevers and acute inflammations. The force of the heart being diminished, the fever is allayed; and the active congestion of the vascular system, whether local or general, which was produced by the inflammation, and maintained by the violent action of the heart, is effectually subdued. At the same time absorption is favoured by the removal of the pressure from the capillary circulation.

For its power therefore as a Special Sedative, by which it produces nausea, Antimony is used in sthenic inflammations generally, especially in those that are rapid, and in which we desire a sudden and powerful action. In such cases it is preferable to Mercury,—which is a simple Antiphlogistic, acting in the blood, and having no operation on nerve. It is thus indispensable in Croup. It is very efficacious in sthenic Pneumonia. Laennec speaks highly of its use in acute Bronchitis. In Fevers, Dr. Graves recommends that it should be combined with Opium. In inflammations of the lungs it is particularly applicable, for it exerts a sedative influence over the nerves of those organs.

If a small dose be constantly repeated, and gradually increased to a large one, the system will at length be induced to tolerate the medicine, and it will not produce vomiting. Laennec recommended that it should be given in this way in inflammations. He considered the production of vomiting unadvisable; for by that act the system is temporarily excited, and a large quantity of the medicine rejected, which should have been absorbed into the blood to work out its action there. The soundness of his views on this point has been generally admitted by those who have succeeded him.

Given simply as an Emetic, this medicine has been used in the early stage of acute local inflammations, as Ophthalmia and Gonorrhoea. It may cut these short at their outset, by hindering the tendency of the local irritation to excite the force of the heart. When we wish simply to evacuate the stomach, as in a case of poisoning, an irritant emetic, as Mustard or Sulphate of Zinc, which acts at once without producing nausea, should be preferred, for three reasons. Its operation is more rapid. The distressing condition of nausea would be an aggravation of the existing mischief. And the production of nausea, by taking off the pressure from the vascular system, favours absorption, which is the very thing that we wish to avoid. The object of an antimonial Emetic is not so much to empty the stomach as to make a powerful impression on the system.

The influence of Antimony on the glandular organs is indirectly but powerfully intensified by its nauseant action. In small doses it is a simple Expectorant; in nauseant doses, it assists expectoration by relaxing the bronchial tubes, and diminishing the number of the respirations. In a small dose it is Diaphoretic; but in large doses it may cause copious sweating, by favouring the absorption of fluid into the blood, and dilating the capillaries and pores of the sudorific glands. In inflammatory habits a small addition of Tartar Emetic forms a powerful adjunct to a purgative dose; for by it the absorption of the other medicine is assisted, and at the same time an over-tonicity of the muscular fibre of the intestine may be diminished. But in relaxed conditions of the system, where the intestine is apt to be over-dilated, and Catharsis is favoured by Tonic medicines,—Tartar Emetic would hinder it.

Ipecacuanha, a vegetable substance, resembles Antimony in all its operations, excepting its blood-action. It is less potent as a Neurotic; less efficacious as a Diaphoretic; but excels it as an Expectorant. (Vide pp. 93, 168, 185, 249, 283, 298.)

MERCURY.

Class I. Div. II. Ord. I. Antiphlogistica.

Class I. Div. II. Ord. II. Antisyphilitica.

Class IV. Ord. III. Cathartica.

Class IV. Ord. IV. Cholagoga.

There are three principal forms in which this medicine may be exhibited. Blue pill contains the metal itself in a finely divided state, as well as a small quantity of the oxide. Calomel is an insoluble Chloride of Mercury. From the great similarity that exists between the action of these two it seems likely that they are reduced by the gastric fluid to the same condition. Both must be rendered soluble (p. 88) before they can be absorbed. Probably they are both absorbed in combination with the acid of the stomach.

Bichloride of Mercury is soluble in water, and probably absorbed unchanged. It differs from the other two as a medicine, partly, but not entirely, on account of its solubility. The dose required is smaller, for it is much more powerful. It is also much more irritant, being in large doses a corrosive poison, and often producing soreness of the throat and of the urinary passages. Thirdly, it is less likely to produce salivation. It is more adapted for chronic than for acute diseases.

As HÆmatic medicines, Mercurials have a double action. They counteract inflammation in general, and the poisons of Syphilis in particular. They thus belong to the first and second orders of Catalytics.

Mercury deteriorates the blood, diminishing in it the amount of fibrine and corpuscles. As an anti-inflammatory agent, it may be thus compared with Antimony and Blood-letting. The immediate effect of Blood-letting is mechanical; that of Antimony, nervous; that of Mercury, hÆmatic. Blood-letting weakens the force of the heart by diminishing the pressure on the vessels; Antimony diminishes the pressure on the vessels by weakening the force of the heart; and Mercury does both of these things, by impoverishing the blood. Thus all of them favour absorption, and counteract effusion; but, from its nature, the action of Mercury is slower than that of the others, and for the same reason more lasting. To produce this action on the blood, the Mercurial should be continued until some effect on the mouth is perceived, but not so as to cause copious salivation. This symptom is a sign that the blood is sufficiently saturated with the medicine. This point will be sooner reached if the Mercury be conjoined with Opium, so as to prevent it from passing out directly by the bowels. Any ill result is less likely to occur if the patient be kept warm and quiet while under the influence of the medicine. On account of the durable and effectual nature of its action, Mercury is of great use in preventing the process of effusion, and in causing the absorption of effused products. It is thus employed with advantage in Pleurisy, and in other membranous inflammations. Next to these, it is most useful in inflammations of the liver and brain. It is inferior to Antimony in fevers and rapid inflammations, because slower in operation, and without any direct action on the nervous system.

In cases of primary Syphilis, Mercury is by far the best medicine with which we are acquainted. It should be used in all cases except where there is deep-rooted scrofula, or marked debility, or a sloughing and irregular condition of the primary sore. (Dr. Pereira.) It should always be given in Iritis. In Periostitis, and secondary eruptions, Iodide of Potassium is generally preferable.

Mercury, being unnatural to the blood, passes at length out of the system through the glands, and acts as an Eliminative. Like Antimony it tends to increase all the secretions in the body. But whereas Antimony acts especially on the secretions of the skin and pulmonary membrane, Mercury tends particularly to excite the functions of the liver and bowels, being Cathartic and Cholagogue. Of its true eliminative action we have better proof than has yet been obtained in the case of Antimony; for Mercury has been found to pass into the alvine excretions, by M. Lehmann; and discovered in the bile of dogs to whom it had been administered, by M. Buchheim.

For the purpose of acting upon the liver and bowels, Mercurials are frequently used in disordered digestion and cases of hepatic derangement. In Intermittent disorders, debility, Gout, Rheumatism, and Scrofula, small doses of Mercury are often of service. I have endeavoured to show (p. 143) that in these cases they may prove indirectly tonic, by restoring to the system some of the wanting elements of bile, which are normally secreted by the liver for the purpose of being reabsorbed into the system.

In incipient and chronic cases of Scrofula, consumption, and mesenteric disease, it is possible that Mercurials may act yet in another way. They no doubt stimulate the formation of the Pancreatic secretion, which is similar in nature to the saliva. By doing so they may assist the absorption of the fatty matters of the food in the case of thin and emaciated subjects, in whom it is probable that the function of this gland is frequently impaired. (Vide p. 313.)

Mercury assists the operation of all other medicines which act upon the secretions. In cases of hepatic dropsy it helps the action of Diuretics, and tends to remove the cause of the congestion, by stimulating the function of the liver.

The blood-operation of Mercury, by which it is enabled to counteract morbid processes, is involved in considerable obscurity. The same must be said of all Catalytic medicines (Vide p. 179.) Dr. Billing (Principles of Medicine, p. 73) is of opinion that Mercury acts by contracting the capillary vessels. I have already stated my reasons for dissenting from this notion. (p. 163.) The same author denies the specific action of Mercury in Syphilis. But if we only admit that there is no other medicine that will cure primary Syphilis so well as Mercury, we cannot then surely deny that its action in that disorder is of a special nature. He considers it to be neither stimulant nor sedative,—but tonic. (Op. cit. p. 101.) No one of these terms appears to me to be strictly applicable, but perhaps the last is the best of the three.

Some have, without sufficient reason, assumed Calomel to be a Sedative when given in large doses. To act in this way, very large doses have been recommended and given in fever and malignant cholera. Calomel is naturally an insoluble substance; and in these cases the function of absorption is at the very lowest ebb; so that it is probable that the large doses are often left unabsorbed, and pass out of the bowels very much as they entered, producing scarcely any more effect than so much chalk mixture. (Vide pp. 88, 143, 163, 168, 185, 188, 203, 286, 295, 308.)

IODINE.

Class I. Div. II. Ord. II. Antisyphilitica.

Class I. Div. II. Ord. III. Antiscrofulosa.

The readiest and best way of obtaining the beneficial effects of Iodine is by the use of Iodide of Potassium. This is a very soluble salt. The peculiar virtues of Iodine are not impaired, but rather improved, by its chemical combination with the alkali. And when we administer the Iodine itself, as in the tincture, there is no doubt that after entry into the blood it combines with some alkaline base.

If the use of Iodine be continued for some time it has the effect of impoverishing the blood. It sometimes produces a vesicular eruption on the skin, and causes a considerable degree of irritation of the mucous membrane of the nose and eyes.

The preparations of Iodine exert in the blood some special actions of a Catalytic kind, by virtue of which they are enabled to counteract the morbid actions of secondary Syphilis and of Scrofula. Iodine is not, like Mercury, a general Antiphlogistic; but it is a stimulator of the function of absorption, as are all the medicines that tend to impoverish the blood. This action in causing absorption can be no explanation of the blood-operations for which it is employed; for these are peculiar to it alone, whereas the other property is shared by other remedies. (P. 192.)

Iodine is an Antisyphilitic. But this term is not applicable to it in exactly the same sense as to Mercury. Its use is confined to the later symptoms,—to Periostitis, and the late eruptions, as Rupia. Sometimes it even fails in these. This is generally when the primary disorder has not been met by Mercury. Some preparation of Mercury should then be administered for awhile; and the Iodide of Potassium may be given afterwards. Thus the disorder which is controlled by the latter medicine is so modified as to be something quite distinct from the primary Syphilis.

The same medicine is an Antiscrofulic. It is applicable in all the forms of Scrofula, and in Goitre. Possibly it acts differently in such cases; but it is certain that there is often, in cases of confirmed Syphilis, a cachexy similar to that produced by Scrofula. In either disorder, when this cachexy is confirmed, Mercury is most objectionable. On the contrary, in primary Syphilis, and even in incipient Scrofula, Mercury may be used.

Like all potent remedies, Iodine requires to be carefully used. It is sufficient to give it in small doses. If given in large doses, and too long continued, it causes a deterioration of the blood, followed by an emaciation of the whole frame. So vigorously was this medicine used by the Swiss practitioners after its first discovery, that serious consequences, as the absorption of the mammÆ or the testes of healthy individuals, are said to have ensued in several cases. By these mishaps their faith in its utility was much shaken. But M. Magendie states that he has never known such a thing to occur; and M. Lugol, the most devoted and enthusiastic of all the advocates of Iodine, has observed that scrofulous patients frequently become fattened during its employment.

The therapeutic actions of Iodine have been ascribed by Dr. Billing to a contraction of the capillary vessels; by Dr. Pereira, to a liquefaction of the blood; by others, to a direct stimulation of the absorbent system. It probably counteracts morbid operations in some way that we do not understand. It is one of those medicines which tend to increase secretion in general. It appears to act most upon the urine, but is not a powerful Eliminative. It has been chemically discovered in the blood, urine, and sweat; as also in the saliva, tears, and nasal mucus, which secretions are apt to be increased in quantity during its action.

The Iodide of Potassium should be cautiously administered to excitable patients, as it sometimes acts as an irritant. When the stomach is irritable, it should be given after meals, and the dose considerably diluted with water.

A bronchocele, to be benefited by Iodine, should consist of a simple enlargement of the gland, not of very long standing, nor painful to the touch. All scrofulous affections, whether of the glands, joints, liver, or other parts, are more or less benefited by the use of Iodine. Iodine has been used in simple enlargement and induration of various organs, particularly the uterus. Dr. A. T. Thomson speaks highly of its efficacy in ovarian dropsy.

It is probable that Chlorine, Bromine, and their compounds, closely resemble the preparations of Iodine in their therapeutic operations. (Vide pp. 169, 188, 191, 306.)

COLCHICUM.

Class I. Div. II. Ord IV. Antiarthritica.

Class II. Div. III. Ord. I. Sedantia Generalia.

Class IV. Ord. III. Cathartica.

The majority of medicines that affect the blood permanently belong to the mineral kingdom, while most of those that powerfully impress the nerves are derived from vegetables. But to the rule that HÆmatic medicines are of mineral origin, we have already found one important exception in the case of Quinine and Tonics. Colchicum appears to be another instance of the kind. The great and obvious use of this remedy is that action in the blood which above is classed first, i.e. its influence in the counteraction of gouty disorders. We have already considered at some length (p. 200) a number of Antiarthritic medicines that seem to act in a chemical manner. Colchicum is not one of these. It is a General Sedative, and a Cathartic; in large doses, an irritant poison. It seems also to increase the amount of other secretions, particularly the urine and the bile. But it is used beneficially in Gout; and it is assumed that in the cure of this disorder it exerts an action in the blood, inasmuch as its remedial operation appears to be independent of its nervous and glandular actions. This hÆmatic action must be of the Catalytic kind, and may probably consist in the exertion of a special influence over the erring assimilative processes, which tends to resolve them into a right direction.

But it should be observed that at least three other explanations of the action of this remedy have been proposed, each of which is possessed of a degree of plausibility.

Some have ascribed its efficacy to the union of a cathartic with a sedative effect, and have even substituted for it a combination of Opium with a drastic purgative. Those who adopt this view of its action aver that Colchicum acts best when it purges freely. But though Purgatives are often of use in gouty disorders, it is generally found that Colchicum operates most favourably when given in too small a dose to produce any purging.

Colchicum stimulates the function of the liver, which is generally deranged in gouty disorders. Mercury, which also promotes the secretion of bile, is in this way useful in Gout. It seems that the formation of this secretion is in some manner essential to the integrity of those blood-processes which are disturbed in arthritic diseases. It might therefore be supposed that Colchicum too acted as a Cholagogue. But it is not clear that it increases the secretion of the bile in any very marked degree.

Thirdly, it is affirmed by some that this medicine is of use in eliminating uric acid from the blood, this product being supposed to accumulate in the system before the paroxysm of Gout. It is said that under the action of Colchicum the natural amount of this substance in the urine is much increased. This would be an important fact if it were certainly proved. But it does not seem to be so; nor is it clearly shown that the observed increase in uric acid is not a symptom of the disorder, rather than of the treatment.

Colchicum is more or less applicable in the gouty forms of Rheumatism, in Lithiasis, and in acid dyspepsia, but it is most efficient in the simple gouty paroxysm.

There are several objections to the indiscriminate use of this remedy. Some have observed that though it cures for a time the gouty attack, it causes the next assault of the disease to recur more quickly than it would otherwise have done. The dose also certainly requires to be considerably increased on each successive occasion. Sometimes this medicine produces a great depression of the spirits. Dr. Todd believes that Colchicum has often a tendency to change the common acute form of Gout into an asthenic form which is less amenable to treatment. So that, altogether, it is perhaps a good rule to treat the patient without Colchicum as long as it can be done with safety, adopting this medicine only as a last resource, when other remedies have been tried and failed. It ought rarely to be used in Rheumatism. In the asthenic form of Gout, or in old chronic cases, when there are chalk-stones on the knuckles, Quinine, Stimulants, and Purgatives, constitute the best treatment. Alkalies and Mercurials may prove serviceable in acute cases.

But it is certain that in many cases of this painful disorder Colchicum gives immense relief; and it often seems to be the only medicine that is capable of doing so. (Vide pp. 194, 247.)

ARSENIC.

Class I. Div. II. Ord. VI. Antiphriodica.

Class I. Div. II. Ord. VII. Anticonvulsiva.

Class I. Div. II. Ord. VIII. Antisquamosa.

This medicine has already been noticed at considerable length in the account of the last three orders of Catalytic medicines. It is again noticed here as one of the most remarkable of those mineral substances that are used to counteract blood-disorders. It appears to be capable of exerting no less than three kinds of action in the blood, which operations result in the counteraction of Periodic disorders, Convulsive diseases, and certain Cutaneous eruptions. That must of necessity be a various and obscure agency, which is gifted with the power of arresting and controlling so great a variety of morbid actions.

It would seem that Ague and its kindred disorders are capable of being combated and cured in two different ways; by Restoratives, such as Quina, which appear to supply the blood with a certain needful material; or by Catalytics, as Arsenious acid, which operate by antagonizing a morbid action, which is either the cause or the result of the blood-disease. I have given my reasons for ranking Quina and Tonics among Restorative medicines. The following are the principal grounds for which Arsenic is included among Catalytics. It is unnatural to the blood, and is at length excreted from the system. It acts as a poison; and is able to work out in the blood a certain process of its own. It has no sudden action on the nervous system, like that which is possessed by Neurotic medicines. And it is able to counteract a number of disorders, as Lepra and Impetigo, which are assumed to depend upon morbid actions in the blood.

Arsenic has been recommended in Syphilis, but it exerts no marked power over that disorder. In ague it possesses this advantage over Quina, that it may be administered with safety during the paroxysm. The ordinary precautions in the administration of the Arsenical solution (Liquor PotassÆ Arsenitis) have been already enumerated, viz., that the dose should be small at first, and afterwards gradually increased; that as soon as it produces swelling of the face and eyelids, or irritation of the stomach, it should be discontinued, or the dose reduced; and that it should generally be given on a full stomach, as it is then less likely to irritate. (Vide pp. 140, 165, 170, 176, 207, 211, 213.)

AMMONIA.

Class I. Div. I. Ord. III. Alkalia.

Class II. Div. I. Ord. I. Stimulantia Generalia.

Class IV. Ord. II. Expectorantia.

Class IV. Ord. V. Diaphoretica.

This medicine may be taken as the type of simple General Stimulants. It tends to excite the nervous forces generally. The remedies of this group are not very potent in their action, Ammonia being perhaps as powerful as any of them. Alcohol, an Inebriant Narcotic, produces at first a greater stimulant effect, but its action is followed up by a depression of the nervous forces, and an affection of the powers of the mind. This influence over the intellectual functions is confined to the Narcotic division of nerve-medicines, and is not possessed by Ammonia.

Ammonia is capable of acting chemically as an alkali in the system, and may be used in the various cases in which alkalies are wont to be employed; but it is inferior to Potash in such disorders, because its affinities are far less powerful than those of that alkali. It is also caustic and irritant when applied externally in any form.

Administered internally in solution, it has a power of quickening the action of the heart, and exciting the circulation generally. It is therefore particularly useful in the common case of fainting, or threatened syncope. This stimulant power is possessed only by the free alkali and its carbonates. And as the secretion of the stomach is acid, Dr. Pereira supposes that the free or carbonated Ammonia becomes neutralized before absorption; that it is therefore unable to act in the blood except as a salt, and can only operate as a Stimulant while in contact with the coat of the stomach. Its influence must then be conducted by the nerves from the surface of the stomach to the heart. But though the nerves are the natural channels of various motor and sensory impressions, it is to assume an unprecedented thing to suppose that a medicinal action can be transmitted by their means to a distant part. For this and for other reasons it seems to me to be most likely that the solution of Ammonia is absorbed too fast in the stomach to be neutralized by the gastric juice. Or even if it were neutralized before absorption, it would probably be again set free on entrance into the blood, in which there is a slight excess of alkaline matter. Thus Ammonia would exist in the blood in a free state, except in those morbid conditions in which there is a general excess of acid in the system. I suppose the same to be the case with Potash, when it is given in any quantity. The great diffusibility of the free Ammonia would be an additional reason for its rapid absorption. When the gas is inhaled, as in the use of smelling-salts, and applied thus to the nasal and pulmonary mucous membranes, it must pass through to the blood in a free state, for these surfaces do not secrete an acid. And yet its effects in this case are the same as when it is taken into the stomach, which further renders it probable that in the latter instance it is absorbed free.

When there is an excess of acid in the system, Ammonia may be used as a Restorative. It diminishes the acid reaction of the secretions by combining with the acid to form a salt.

In ordinary conditions (i.e. when not required in the system) it has to be excreted from the blood. Both Ammonia and its salts act as Expectorants and Diaphoretics, being excreted on the mucous surface of the lungs, and on the skin. Free Ammonia is a better Expectorant than any of its neutral salts. The secretion of sweat contains an acid. The Ammonia which passes out on the skin combines with this acid. But on the pulmonary surface it is probably excreted free. For it is found that the careful inhalation of Ammoniacal gas has the same effect in augmenting the mucous secretion as the internal use of Ammonia. Ammonia is volatile, and soluble in air; and tends for that reason to pass off freely from those secreting surfaces which are immediately in contact with the atmosphere. (P. 278.)

It is supposed by some that diffusible Stimulants act simply on the ganglionic system of nerves, being able through them to excite the functions of the heart, vessels, and glands. But Ammonia is used with advantage in some cases in which the whole nervous system is implicated in the disorder. It has been employed in cases of Typhus, of simple febrile exhaustion, of Hysteria, Epilepsy. In such affections the brain is at least involved, if not often the chief seat of the disorder.

Spasms and convulsions are due to a general derangement of the nervous forces, and particularly of the brain, in which these centre and originate. Stimulants, by exalting the natural functions, counteract and control this derangement. It is thus that Ammonia and volatile oils are of use in convulsive disorders; but they are seldom of any permanent efficacy, as in most cases of Hysteria and Epilepsy there is at the bottom a blood-disease, of which the spasmodic fits are only the symptom and outbreak. (Vide p. 176.) So also is there a limit to the efficiency of Stimulants in such cases as Typhus fever; there is a certain point of exhaustion beyond which they are of no avail. For I have attempted to show that though Stimulants are competent to exalt nervous force, they are unable to supply vital force. A degree of nervous force is necessary to the continuance of life; but when the powers of life themselves are ebbing away, it is impossible then to prolong any further the thread of existence by the exhibition of stimulant medicines.

The action of Ammonia is directly the reverse of that of Prussic acid, which is a General Sedative, producing Convulsions and Syncope. Ammonia is thus used in cases of poisoning by that liquid. (Vide pp. 126, 227, 278, 283, 301.).

STRYCHNIA.

Class II. Div. I. Ord. II. Stimulantia Specifica.

Strychnia is the chief alkaloid and active principle of Nux Vomica. This medicine is comparatively simple in its action. It has no claim to the title of Sedative, which is sometimes applied to it. It does not affect the nerves generally. It has no direct action on the brain, but stimulates chiefly the function of the spinal cord, and its system of nerves. Of these nerves it affects the motor considerably more than the sensory branches. Along with the spinal cord, it doubtless also acts upon that part of the brain which is immediately associated with the spinal system of nerves. But the function of reflex motion, which is thought to reside in the spinal cord, is particularly stimulated.

Strychnia is thus an exciter of muscular contraction and of motion; exalting sensation in a less degree. It has also apparently some action on part of the ganglionic system of nerves, by which it is enabled to promote the function of the stomach, and becomes temporarily a tonic when given in relaxed conditions of that organ. But it does not excite the action of the heart.

In cases of poisoning by Nux Vomica, the brain and the heart are unaffected. Tetanic and general convulsions are produced; and the immediate cause of death is a spasm of the muscles of respiration.

Strychnia causes a contraction of the muscles by stimulating the motor centres, and originating in them an impulse which is propagated along the motor nerves. So that when these centres are diseased, or the continuity of their fibres destroyed, it is unable to exert its power. It is used as a medicine in cases of Paralysis. But when the lesion of the nervous centre is of recent occurrence, or when it has been of so serious or extensive a nature as to admit of no repair in the course of time, the remedy will be ineffectual. It is only successful in cases where the injury to the nervous centre has healed up, and where the limb continues paralyzed merely because the motor nerves have lost the power to transmit the necessary impulse, from having been so long unaccustomed to the discharge of this office.

As it is able to act on the nerve itself, it is sometimes thought best to apply it to the affected part on a raw surface produced by a blister. The advantage of this plan is most obvious in the case of Lead-palsy, where the cause of the paralysis is local, residing in the nerve, and not in the centre. But in this case also it is necessary that the nerve-centre be sound. Dr. Neligan recommends Strychnia in Lead-colic, in which disorder constipation and distention of the bowel are produced by a paralysis of a portion of the large intestine.

Strychnia has been used with benefit by Dr. Golding Bird in cases of Phosphaturia connected with a functional derangement of the spinal cord. (Vide p. 232.)

ALCOHOL

Class II. Div. II. Ord. I. Narcotica Inebriantia.

Class IV. Ord. V. Diaphoretica.

Class IV. Ord. VI. Diuretica.

We have already considered in order the peculiarities in action that distinguish Narcotics alike from Stimulant and Sedative medicines; how they tend first to exalt the nervous forces, and then to depress them, and have further a particular action on the intellectual part of the brain. We have observed that these remedies may be divided into three minor groups, which differ considerably, if only regarded in their action on the nervous forces generally. For that Inebriants approach very nearly to Stimulants, and Deliriants to Sedatives, while Soporifics occupy an intermediate place. We have seen also that though, during the stage of stimulation, these three orders tend all more or less to excite the powers of the mind, they differ characteristically in their secondary or depressing effect upon the same. That, with respect to our present purpose, the intellectual functions may be divided into three parts: the mind itself; volition and sensation, by which it is united to the body; and the special senses, by means of which it is connected with external things. And that the secondary or depressing action of Inebriants is such as to impair these three in a tolerably equal degree; that of Soporifics extinguishes for a time sensation, volition, and the five senses, while it may leave the mind unaffected; but that of Deliriants excites and deranges all the intellectual functions.

If these things are borne in mind, the physiological action of Alcohol will be tolerably understood when it is said to be an Inebriant Narcotic. But it must be observed that when given in small quantities its stimulant effect may be the chief action manifested, its secondary sedative effect may hardly take place, and the production of Inebriation, or drunkenness, may be altogether avoided. So much is this the case that Alcohol is by some regarded as a Stimulant. But the same thing is remarked of Opium, though in a less degree. And the effects of a large dose of Alcohol are sufficiently obvious to indicate its place amongst Narcotics. For the state of Inebriation may even pass on into coma, and death.

In small quantities, for the purpose of producing exhilaration, and of overcoming various depressing causes which are of daily occurrence, alcoholic liquors of various kinds, Beer, Wine, and Spirits, are habitually employed by a large portion of mankind. On the broad and important question of their use and abuse as articles of diet this is not the opportunity to enter.

In the form of Brandy (which is more agreeable to the palate,) Alcohol is applicable as a medicine in low Fevers, in asthenic Erysipelas, in Typhoid forms of Pneumonia, and in Collapse or Syncope produced by surgical injuries or other causes. It restores the action of the heart, and enables the system to bear up against the disorder. The stimulant action may be maintained, and the secondary sedative effect prevented, by a continual repetition of the dose. Thus when once the employment of this stimulant has been determined upon, it should be steadily and unremittingly persevered in until decided symptoms of improvement have shown themselves in the patient.

The tendency of the practice of the present day is towards a freer use of Stimulants, and a more sparing employment of blood-letting and antiphlogistic agents, than was some time ago prescribed. And this is probably an advance in the right direction; for in morbid actions there is altogether very little that is really sthenic; and it is, as a general rule, a wiser thing to support the system against the wearing action of a disorder, than to add to the heap of its various troubles another depressing cause.

But Alcohol is a potent agent for evil as well as for good. When large quantities are taken continually for a considerable length of time, it is capable of producing a chronic injury of the brain and mind. By impairing the function of the former, it brings on the shaking paralysis of Delirium tremens. By an action on the mind, it causes the strange hallucinations and the habitual despondency which characterize that disorder. Habitual drinking may likewise cause a chronic inflammation of the liver, called Cirrhosis, which is succeeded by Dropsy. Alcohol is absorbed by the stomach; and, on passing through the Portal vein to the liver, may there produce this condition of the organ by the continual irritation which it excites.

When taken in considerable quantity Alcohol passes out of the system by the skin and kidneys, and thus acts as a Diaphoretic and Diuretic.

But Liebig states that when taken in small quantities it does not pass off in the secretions, but is consumed or burnt in the system into Carbonic Acid and water. He has found that persons who are accustomed to take Beer in moderation require less bread in their food. (Animal Chemistry, Part I., p. 96.) And as it contains more Hydrogen than starchy food, and by the combustion of this Hydrogen the animal heat is partly maintained, Vierordt has shown that during the use of alcoholic liquors the amount of Carbonic Acid exhaled by the lungs is diminished. Thus Alcohol may be regarded as one of the calorifacient articles of food. (Vide pp. 234, 237, 241, 255.)

CHLOROFORM.

Class II. Div. II. Ord. I. Narcotica Inebriantia.

Class IV. Ord. V. Diaphoretica.

Class IV. Ord. VI. Diuretica.

Chloroform, or Terchloride of Formyle, is a volatile liquid which is analogous to Ether and Alcohol both in nature and medicinal action, but very different in chemical construction.

A solution of Chloroform in spirit, sold under the names Terchloride of Carbon and Chloric ether, is in very general use, and is employed in very much the same cases as Nitric ether, being in the first place stimulant, and subsequently anodyne, soporific, and diaphoretic.

Chloroform is physiologically an Inebriant. But it is for certain peculiar actions that are coincident with, or immediately follow, this production of inebriation, that it has been so widely and so successfully employed in medicine since its recent discovery. Its two important operations are its anÆsthetic effect on sensory nerves, and its paralyzing influence on muscle.

With regard first to the general selection of anÆsthetic or anodyne remedies, it is to be observed that there are four distinct kinds of Pain, which differ very much in the treatment required. (1.) Firstly, there is inflammatory pain, caused by an active disease. It is aggravated by pressure; and it has a local cause. For this Opium is the best Neurotic remedy, but it should not be used without an attempt being previously or at the same time made to subdue the active inflammation. (2.) Irritative pain is different. It depends merely on nervous irritation. It also has a local origin; but it is relieved, instead of being aggravated, by a pressure or friction. Such is the pain produced by lead-colic, or by the passage of a gallstone or renal calculus. The pain of Neuralgia is generally of the irritative kind. So is that of Gastrodynia. So also the pain artificially inflicted by the knife in surgical operations. For irritative pain on the surface Aconite is most efficacious. Belladonna comes next to it. In Gastrodynia Hydrocyanic Acid is to be preferred. But to counteract the pain of a surgical operation we require a medicine which shall be capable of producing a powerful effect on the whole system at once. Such medicines are Ether and Chloroform. It is found most convenient to bring the patient under their influence by causing him to inhale the vapour into his lungs. Being absorbed by the pulmonary mucous surface, and passing directly into the circulation, the medicine thus takes effect rapidly. There is no time for the volatile liquid to be excreted from the blood, so that the ulterior effect of the anÆsthetic cannot be escaped. The third and most important advantage of this mode of administering Chloroform is that by it we are enabled to regulate with exactness the degree of its action, which is a dangerous one, and to stop it when it has gone far enough. When introduced by inhalation into the general circulation, Chloroform acts upon the brain and sensory nerves throughout the body, so as completely to extinguish their natural sensibility. It is thus an agent of immense value where we wish to save the patient from an extreme and agonizing degree of irritative pain, whether to be caused by the edge of a cutting instrument, or by the throes of parturition. But it also acts as an anÆsthetic when applied locally, as to a painful ulcer, or a hollow tooth-stump. (3.) The third kind of pain is reflex in its origin; as the pain in the knee in Hip-joint disease. We should do no good if we troubled ourselves to combat the local symptom in such a case; we should rather direct our attention to that condition which is the distant cause of the pain. (4.) A fourth kind of pain may be called eccentric. Like the last, it does not originate in the painful part. It has its origin in the brain or nervous centres. Of such a kind are the various pains of Hysteria. Local anÆsthetics are here worse than useless. The brain disorder must, if possible, be remedied.

Chloroform is better adapted for inhalation than Ether, because it is considerably less irritating. It is, on the whole, very safe, when proper care is taken. And yet it cannot be denied that sudden deaths have occurred from the use of Chloroform, which could not have been avoided by any known precautions. Such an admission tells little against the remedy; for supposing the proportion of deaths from inhalation to be about 1 in 10,000, it must be confessed that it is better that one out of that number should die of the Chloroform than that 100 should die of fright. Out of 9000 cases of its inhalation at St. Bartholomew's Hospital it is reported that not one died of the anÆsthetic.

The stages of the action of Chloroform when inhaled may be briefly stated as follows: 1st stage: some alteration in the feelings of the patient; 2d stage: inebriation; the mind and volition are impaired; consciousness remains; 3d stage: unconsciousness; anÆsthesia.[48] The loss of sensibility may even occur in the second stage, the patient remaining conscious. The inhalation should not be prolonged beyond the occurrence of the third stage. The pulse is still full. There may be muscular movements, or even cries. In the next stage there is stertorous breathing; the eyelids no longer contract when touched with the finger; the pulse is felt to falter. This is dangerous. To this succeed stoppage of the heart and respiration;—death.

There are four rules which it is safe to follow in the administration of Chloroform; not to go on when there is stertorous breathing; not to administer it when there exists any serious disease of the heart or lungs; not to undertake under its influence an extensive operation on the mouth or jaws; and so to arrange the process as that the vapour shall be freely diluted with air. If the third rule be neglected, the blood may flow into the windpipe and cause suffocation, for the patient is deprived of the power of swallowing. The dilution with air is necessary, not only to moderate the action of the remedy, but that the necessary vital function of respiration may not be interfered with. It is also well known that it is convenient to administer Chloroform on an empty stomach, or it will be likely to produce vomiting.

Though Chloroform rarely fails to annihilate pain, and thus greatly to diminish the terror of the patient, it will not prevent him from sometimes dying of the shock of a serious operation. An extensive injury to the body will suffice to produce a prejudicial effect upon the heart and nervous system, which is independent of the feeling of pain, and may occur without moral suffering.

Chloroform is employed by some to relieve the pain of parturition. It is not found to interrupt the action of the uterus.

But, with this exception, it is a general muscular relaxer and paralyzer, and may thus be inhaled before an attempt to reduce an old dislocation, or to restore a hernia of long standing. It is more efficient in such cases than either Opium or Tartar Emetic, and produces less distress than the latter. For the same operation it is sometimes employed in spasmodic disorders. It has even been known to arrest the paroxysm of that most incurable of all disorders, Tetanus. I have known it to do great service both in Epilepsy and in Hysteria, when ordered to be inhaled regularly twice a day. It has been highly recommended by some who have tried it in Delirium tremens. (Vide p. 237.)

OPIUM.

Class II. Div. II. Ord. II. Narcotica Somnifera.

Class IV. Ord. V. Diaphoretica.

Opium is the chief member of the second division of Narcotics, which consist of medicines that, in their action on the heart, are about intermediate between Stimulants and Sedatives, and in their secondary action, on the intellectual functions produce in them, the condition of sleep (p. 239.) Opium produces at first some stimulation, and exhilaration of the mind, with a full pulse, and general febrile excitement. This soon subsides, and is succeeded by drowsiness and sleep. Large doses cause slowness of the pulse, slow and difficult breathing, and coma. If a small dose of Opium be continually repeated, the stimulant action may be maintained for a time, and the Narcotic effect prevented. But whenever it is taken habitually, the dose will require to be gradually increased, or the desired effect will not be produced, for the system is induced by degrees to tolerate the remedy in larger and larger quantities. Given in moderate doses, it powerfully relieves pain, and controls nervous irritability. Though it always tends to produce sleep, its anodyne effect may take place without its soporific action.

It is useful in the painful inflammations of the serous and mucous membranes. But it tends to cause congestion of the brain. It should thus be generally avoided in brain-disorders; and, on account of its primary stimulant action, it should only be very cautiously used, or altogether avoided in cases of high fever, where there is a hot dry skin, or a full and hard pulse. The system may sometimes be prepared for it by antiphlogistic treatment; or Tartar Emetic or Ipecacuanha may be conjoined with the dose of Opium. Ipecacuanha and Opium are combined in Dover's powder.

Opium is a Diaphoretic; but it diminishes all the other secretions, and most especially that of the bowels. In the treatment of fevers and inflammations it is often combined with Calomel, for the purpose of preventing the latter from passing out by the bowels, and of allaying at the same time the nervous excitement and pain.

Whether any precise connexion may exist between these various actions of Opium, is a difficult thing to determine. It is certain that there are other Narcotics and Sedatives which are able to relieve pain, but which neither cause constipation, nor produce cerebral congestion. Purgative medicines, which open the bowels and diminish cerebral congestion, are so far opposed to Opium. Those effete matters which it is the function of the bowels to excrete from the blood, and whose excretion is promoted by purgative medicines, have an action on the brain which in some degree resembles that of Opium. Constipation produces drowsiness, and torpor of the mental faculties. And it is worthy of remark that Opium does not seem to produce quite its proper effect when combined with a medicine which causes purging. Thus it is barely possible that the action of Opium in causing congestion of the brain may be in part referrible to the influence of those excrementitious matters which it hinders from passing out through the intestinal glands (p. 291.) But nothing conclusive is known on the subject.

How, we may ask in the next place, does Opium produce constipation? It has none of the characters of a general Astringent, and yet there is no Astringent like it in its action on the bowels. An attempt has been made to explain it on mechanical grounds. Poisseuille some time ago asserted that a solution of Morphia prevented the process of endosmosis through a dead animal membrane. Matteucci and others account for the operation of Opium on this principle, supposing that by exerting this action on the living mucous membrane, it is able to prevent the transudation of fluids from the blood into the cavity of the bowel. But this view seems even at first sight unsatisfactory. If such a force is really exerted, and the passage of fluids through a membrane prevented by the action of Opium, must it not apply to the stomach as well as to the bowel? Why is Morphia absorbed at all? It should stop the digestive process altogether. And why is the secretion of the skin increased by Opium, while that of the bowels is suppressed? (Vide Matteucci's Lectures, p. 74.)

But there is reason to suppose that a serious error of observation has been made by those who first asserted that a solution of Morphia tended to arrest the process of endosmosis. Dr. Cogswell has lately made some careful experiments on the subject, and he finds that a solution of Muriate of Morphia passes readily through the bladder of an endosmometer to serum or a heavy saline solution. And when experiments are made on two other liquids of different density, the addition of Morphia to one or other of them is found to effect no alteration in the direction or rapidity of the current.

Opium is a general paralyzer to muscular fibre, both of the voluntary and involuntary kind, but particularly of the latter. And the only reasonable attempt that can be made to explain the action of Opium in producing constipation, is by a reference to this its paralyzing influence on the coat of the bowel, taken in conjunction with the torpid condition of the general system, and suspension of the animal functions, produced by the secondary action of this Narcotic on the nervous forces.

A considerable dose of Opium produces contraction of the pupil of the eye. A larger dose causes coma. The Deliriant Narcotics, i. e. Hyoscyamus, Belladonna, and Stramonium, dilate the pupil, and in large doses cause delirium. Their action is thus readily distinguished in cases of poisoning.

Opium is the best internal remedy in all cases of pain and nervous irritation, except where contraindicated by great febrile excitement, by stomach irritation, or by cerebral congestion. It acts powerfully on children, and should be administered to them very cautiously, or not at all. It is given to lessen the secretion in some cases of diarrhoea. It is generally unadvisable to give it when there is constipation or hepatic congestion. In wakefulness, mania, and delirium, when unattended with congestion of the brain or fever, it is highly serviceable. In spasmodic disorders, convulsions, and cough, it is more or less applicable.

That the active principles of Opium are absorbed, and pass into the blood, has been proved by their detection in the urine. (P. 223.) It does not act on the system before time has been allowed for this absorption. If taken by a mother during suckling, it may act upon the infant by passing into the secretion of milk. It acts upon the nervous system, and probably on the muscles also (see note, p. 224,) through the medium of the blood.

As a Diaphoretic in fevers and inflammations, Opium is to be preferred in cases where the skin is already moist and cool, where the pulse is soft, and the tongue not coated. But where there is febrile excitement, Antimony, or Ipecacuanha, is rather indicated. Opium may act on the glands of the skin as a true Eliminative; or it may possibly operate in the same indirect way as a nauseant dose of Tartar Emetic, relaxing the ducts of the sudorific glands by its paralyzing influence on their muscular fibre.

The chemical construction of Opium is a matter of considerable interest. Morphia, the chief active principle, is an alkaloid which is almost identical with Opium in its narcotic actions but slightly more sedative. Unencumbered by inert matters, it presents us with an anodyne in a more concentrated form. But the combination of the Morphia with other principles in the crude Opium is worthy of remark. Both Morphia and Opium are liable occasionally to produce nausea, headache, loss of appetite, and depression of the spirits. There are various ways in which we may try to obviate these unpleasant symptoms. To prevent nausea, we may combine the dose with an aromatic. Dr. Copland has successfully combined Morphia with an aromatic spirit, in cases where alone it was apt to bring on hypochondriasis. And to prevent the loss of appetite in Delirium tremens, Dr. Todd recommends to combine Morphia or Opium with Quinine or some other Tonic. But it is very curious that in the construction of Opium an attempt is made by nature at the very things that we so much desire in practice. For the drug contains, in addition to Morphia, an aromatic volatile oil, and a neutral principle, wrongly called Narcotine, which has been proved by some experiments made in India to be a simple Tonic, like Quinine. So that if we could only separate from the other parts of the drug the Morphia, volatile oil, and Tonic principle, we should obtain an admirable combination made ready to our hand. But Opium contains also other matters which are mere incumbrances, but which are more or less taken up by the various liquid menstrua that we employ; as, an irritant resin; other neutral principles, as narceine, Meconine, and Papaverine,—and Meconic acid,—all of which are probably inert; and, what is worst of all, a small quantity of an alkaloid called Thebaia, said by Magendie to have an action identical with that of Strychnia.

Though Morphia constitutes only about twelve per cent. of the best Opium, the dose of it required is at least one fourth of that of the latter. It seems therefore that Opium must contain some other narcotic principle. Codeia is a Narcotic, of less power than Morphia, and though it is contained in Opium, it is scarcely in sufficient quantity to explain the strength of the drug. It is likely that Opium contains more than one volatile oil, and that the odorous principle to which its peculiar smell is owing is itself narcotic in its action. A parallel case to this is verified in the instance of bitter almonds, which not only yield Hydrocyanic acid, the most powerful Sedative known, but contain a large quantity of a volatile oil, which remarkably resembles the acid in its poisonous action. (Vide pp. 238, 268.)

HYDROCYANIC ACID.

Class II. Div. III. Ord. I. Sedantia Generalia.

Hydrocyanic or prussic acid (C₂ N, H,) a very volatile liquid, soluble in water, is one of those mysterious vegetable compounds which, containing no chemical element that is not also contained in animal structure, are yet gifted with a wonderful power over the vital forces. One drop of the pure acid is sufficient to cause death. But the officinal acid is an aqueous solution, containing only 2 per cent. of the other.

It is a powerful Sedative to the nerves generally. Its action is direct, and is not preceded by any primary stimulation. Diminishing sensibility, it is therefore used as an anodyne. Controlling muscular action, it is employed as an anti-spasmodic. But it appears especially to influence the reflex nervous actions. It is therefore of especial use in the paroxysmal coughs of Hooping-cough and of Phthisis, which have a reflex origin in the irritation of the mucous membrane. It acts on nerves as well as on nerve-centres. Thus it is particularly useful in neuralgic forms of Gastrodynia; and it seems to allay the pain in the stomach by diffusing itself directly it reaches it, so passing through the mucous membrane at all points, and coming in contact every where with the irritated sensory nerves. It is sometimes useful in cases of vomiting, or pyrosis.

If applied to the surface of the skin, it numbs the superficial nerves; but on account of its rapid volatility, and the dangerous results that would follow the inhalation of its vapour, it is not appropriate as an external anaesthetic.

A poisonous dose produces first convulsions of the whole frame, then syncope, and death. Strychnia produces convulsions, but they are not caused in the same way as those of Hydrocyanic acid. For the two medicines are obviously opposed in their action, Strychnia being an exalter of sensation and of reflex action, and Hydrocyanic acid a depresser of the same. The convulsion caused by Strychnia is tonic; that by Hydrocyanic acid, asthenic. The one, being a special Stimulant, causes convulsions by an excitement of the spinal cord; the other, being a Sedative, does it by deranging the function of that centre. (Vide pp. 245, 243.)

ACONITE.

Class II. Div. III. Ord. I. Sedantia Generalia.

This medicine, like the last, is a powerful General Sedative, and a dangerous poison. It depresses the influence of the brain, and paralyzes all the nervous functions. It tends at length to kill by producing syncope.

It acts especially on the superficial sensory nerves, and tends to extinguish feeling and pain. It is the best external anÆsthetic with which we are acquainted. It is thus eminently useful in the treatment of that most painful of all disorders, Tic douloureux, or irritative Neuralgia of the face. When Quinine and all internal remedies have failed, the tincture of Aconite, or an ointment containing the alkaloid, will in most cases, if applied to the part, effectually relieve the pain. It is applicable in local irritative pain at any part of the surface, as in Sciatica, Lumbago, or a Scirrhus of the breast that has not opened. But, like the other local anÆsthetics, it is of little service in cases of inflammatory pain, for this, when local, depends upon an active cause, and would be liable to be increased by the rubbing required in the application of the Aconite. When the remedy takes effect, some heat is first experienced at the part; there is then tingling; and lastly, complete numbness, and a sensation of cold, which endure for some time. No visible change is effected.

Aconite subdues the action of the heart. Dr. Fleming has therefore recommended small doses internally in cases of acute rheumatism. But considerable care is required in the internal employment of the drug, on account not only of its dangerous properties, but of the great variety in strength which exists among the preparations that are usually employed. The difficulty experienced in the preparation of the alkaloid Aconitina, which is the active principle of the plant, and the very high price at which that substance is usually sold, have prevented it from being so extensively employed in practice as its medicinal properties would appear to deserve for it. On account of its cleanliness as an outward application, and the certainty and uniformity of its sedative and anÆsthetic actions, the pure alkaloid is far preferable as a medicine to Aconite itself, and is adapted for all the cases in which the latter has been employed.

Having some time ago been successful in an attempt to discover a mode of preparing Aconitina,[49] I have made some experiments with it on various small animals, for the purpose of ascertaining its power, and the symptoms of its action. It is a very active poison. Proceeding upwards in the animal scale, I find that 1/300th of a grain, in solution in water, suffices to kill a mouse. 1/100th kills a small bird after a few minutes; 1/50th almost instantaneously. 1/20th of a grain has killed a cat. 1/10th invariably proves fatal to the unfortunate feline in the course of twenty minutes or half an hour.

Calculating as well as I can from these data, I consider that 1/10th of a grain of this alkaloid would be sufficient to cause the death of an adult man. During the action of the poison on cats the following succession of symptoms is generally observed. They will illustrate in most of its phases the action of a Sedative medicine.

1. An increased flow of the salivary secretion. (Vide p. 282.)

2. Vomiting.

3. Delirium, with hallucinations. Impairment of volition; apparent loss of sensation.

4. Convulsions; paralysis.

5. Breathing difficult and gasping,—gradually ceasing.

6. Death; pupils of the eye are seen to be dilated.

Aconitina has thus a powerful action on the brain, and on the nerves generally. The flow of saliva seems partly to arise from a paralysis of the fauces. The animal makes ineffectual attempts to swallow, and breathes spasmodically. By a small dose the anÆsthesia would probably be produced, without the other effects. On examination of the body after death the lungs are found to be healthy, but shrunken and bloodless; the trachea contains much frothy mucus, which may possibly have flowed into it on account of the palsy of the glottis; the cavities of the heart are full; the mucous membrane of the stomach pale. It seems then that the immediate cause of death is paralytic syncope,—a loss of power in the heart. As the mucous coat of the stomach evinces no trace of congestion, it is probable that the vomiting is not caused by irritation, but by a sedative or deranging action on the function of the Vagus nerve. (Vide pp. 242, 245.)

DIGITALIS.

Class II. Div. III. Ord. II. Sedantia Specifica.

Class IV. Ord. VI. Diuretica.

This important medicine has already been prominently noticed as one of the agents that exert a special sedative and deranging power over the functions of the Vagus nerve. It will only be necessary now to sum up shortly the details of its action.

It does not depress nervous force generally. It has no action on the brain, except as connected with the Vagus nerve. Neither does it affect the spinal cord, or the nerves of sensation or motion. Its most obvious action in small doses is to depress the force of the heart. It sometimes quickens the pulse, but always weakens it, and reduces its rate in the end. It therefore supplies us with a ready means of weakening the heart, whenever we desire to do this. In cases of hypertrophy, where the heart is too strong,—or in aortic aneurism, or active hemorrhage, where a forcible beat would be dangerous,—Digitalis may be used for this purpose. But it is especially useful in dropsies; for by its action on the heart, it diminishes congestion of the venous system, and by thus removing the pressure from the veins, it favours the absorption of the fluids effused. It should, however, be avoided in cases where there is very serious cardiac obstruction, or where the heart is habitually weak, and there is a natural liability to syncope. For the tendency of the medicine is to cause death by producing syncope.

Certain precautions are necessary in its administration. The patient should be generally confined to the recumbent posture; for if, while under the influence of Digitalis, he should suddenly rise, and the heart, already weakened, have further to contend with the force of gravity in the propulsion of the blood upwards, it may actually stop. The dose also should be cautiously regulated, and, if it do not operate at once, it must not be increased, or too soon repeated; for this medicine is apt sometimes to accumulate in the blood, and though several doses may perhaps be given without effect, they are afterwards liable at any time to be suddenly discharged upon the nervous system, and may then produce by their united action a dangerous result.

A considerable dose of Digitalis, as of Tartar Emetic, deranges the control of the Vagus nerve over the function of the stomach, and may in this way produce nausea and vomiting. There is no reason for supposing that it irritates the coat of the stomach. (Vide p. 93.)

The active principle of Digitalis is secreted from the system in the urine, and probably acts as a true Eliminative Diuretic. But it tends more powerfully to promote diuresis in another indirect way. Any thing which diminishes the pressure on the vascular system, as Digitalis, by weakening the force of the heart, tends thereby to promote absorption, and to increase the secretion of urine.

So that the employment of Digitalis in Dropsy is attended with a twofold advantage; by its cardiac action, it prevents a renewal of the dropsical effusion; by its diuretic power, it causes a quantity of fluid to be drained out of the system through the kidneys. That it may do this the more effectually, it is generally considered advisable to combine it with other diuretics. (Vide pp. 251, 304, 308.)

TANNIC ACID.

Class III. Ord. II. ASTRINGENTIA VEGETABILIA.

This is the chief astringent principle of vegetables. It is very soluble in water, crystallizable, and has a strong astringent taste. It is not possessed of those marked properties that are vulgarly attributed to acids; but its solution reddens litmus-paper, and it combines with bases to form salts.

When received into the stomach, it is absorbed, and passes in the circulation to distant parts. Its action consists in a power of causing the contraction of muscular fibre when in contact with it; and this power appears to depend mainly upon a chemical property that it possesses of coagulating albumen and analogous compounds. Capillary vessels, and the small ducts of glands, contain in their walls certain fibres of unstriped muscle; and Tannic Acid, by causing this muscle to contract, is able to diminish the caliber of these tubes, and thus to moderate or arrest the flow of blood in the vessel, or to lessen the amount of the excretion of the gland. Thus, in all cases of hÆmorrhage from the small vessels, or of inordinate secretion from any glandular organ, Tannic acid is appropriate. It is the best and safest of all Astringents for internal use, excepting only Gallic acid.

I have already stated as worthy of remark the fact that Gallic acid is of little or no use as an Astringent when applied to external parts. Given internally, it is very efficacious. From this alone it would seem that there must be something in the blood which enables it to take effect. Reasons have also been alleged for supposing that Tannic acid is not a simple substance. When it is taken into the system, Gallic acid is secreted in the urine; and it appears that Tannic must actually consist of Gallic acid combined with certain other elements, or with some other definite substance; and that the astringent property which is so valuable is confined to the compound body thus produced. Gallic acid alone has not the power of precipitating albumen.

What then is this other substance? It must be something which is contained in or formed in the blood, which added to Gallic, will be capable of forming Tannic acid; and which, when united to it, will enable Gallic acid to precipitate Albumen. These various requirements are fulfilled by the group of elements that constitutes grape-sugar (C₁₂H₁₂O₁₂.) This compound is continually forming in the blood during the blood-processes that are connected with respiration. It has been observed that a solution of gum (C₁₂H₁₁O₁₁,) added to one of Gallic acid, will enable the latter to coagulate Albumen. And the elements of Tannic acid may be constructed out of those of Gallic acid and grape-sugar.

Three equivalents of anhydrous Tannic acid amount to six of Gallic acid and one of grape-sugar.

So that it is very probable that when Gallic acid is taken into the blood, it acts as an Astringent by co-operating or uniting with the elements of grape-sugar in that fluid. But when Tannic acid is received into the organism, and has done its work there, it is finally decomposed, Gallic acid passing out into the secretions, and the sugar being retained in the body for combustion into carbonic acid and water. (P. 116.)

The principal vegetable substances that are employed as Astringents are said to contain Tannic acid in the following proportions:—

These numbers are a tolerably fair measure of the astringent power of the substances named. But it must not be supposed that the astringent principle is in all cases strictly identical with Tannic acid, properly so called; for there appear to be various modifications of this substance contained in the different plants, many of which have peculiar chemical characters of their own, but all of which agree in possessing the power of tanning, or combining with animal gelatine, and in the medicinal property of astringency.