PHYSIOLOGICAL PROPERTIES. Prejudice is the daughter of ignorance; and nothing exemplifies the truth of this more thoroughly than the senseless repugnance to salt which is now so remarkably prevalent. Ask these persons for their reasons, if we can dignify them as such, for disliking salt; their answers, as a rule, will be trifling platitudes, altogether unworthy of refutation, or even of moderate attention. Objections founded on imperfect, or an affectation of knowledge, are not worth the trouble of confuting, even if they be supported by a fair amount of intelligence; but when the opponents of salt begin to base their assertions upon science, and demur on medicinal, dietetic, and physiological grounds, then we must meet them armed with similar weapons to those they have chosen, with the handling of which they are but imperfectly acquainted, and which therefore recoil upon them in such a way as prove that though they may be shrewd, they are but badly informed and credulous scientists. At the present day the science of physiology has arrived at such a pitch of perfection that there is not a single secretion, tissue, or organ of the body, with the exception of the spleen, which has not been investigated, and the functions divulged and made so plain that it is quite divested of that apparent mystery which formerly enshrouded it; though our kind friends, the anti-vivisectionists, would willingly adopt the most unjust measures to prevent the study of life from being more perfect than it already is: they protest with well-feigned horror at a frog or a rabbit, under the influence of chloroform, being experimented upon for the benefit of humanity, while they see, without allowing a sign of disapprobation to escape from them, an inoffensive hare chased to death for Had it not been for physiological research we should not have known that the chloride of sodium was such an important constituent in the animal economy; we should have been in utter ignorance of the science of life, and we should never have known how man is begotten, how developed, or how he dies. With regard to the two processes of decay and repair, or how the human organism, from a mere cell, gradually becomes a being highly organised, mentally as well as physically, we should have known nothing. Physiology has been a boon to humanity and an inexhaustible field of research to the scientific. In a chemical point of view there is no more important mineral constituent in the human body than the chloride of sodium, for it occurs nearly in every part of the system, both solid and fluid, in close and intimate relation with the organic compounds, and it materially influences their chemical and physical properties; for instance, the albumen partly owes its solubility to the presence of salt, the quantity of which causes the differences which it presents as regards its coagulation; pure caseine, which is quite insoluble, is dissolved at once on the addition of common salt; and if it is added in increased proportions it impedes the coagulation of the fibrine. Another remarkable physiological fact is that the chloride of sodium is not only uniformly present, but its various proportions are nearly definite and constant, both in the fluids and tissues; and the existence of a provision for the limitation of the quantity kept in the system causes the proportions to be little affected, in the way of excess at least, by the amount of salt the food may contain, that is, if the diet is wholesome and the individual healthy. According to Lehmann, who experimentalised on himself, the blood may contain in a normal state 4·14 parts of the chloride of sodium in 1000, and after a meal of very salty food it may be only increased to 4·15; he says it only rose to 4·18 when two ounces of salt had been taken an hour before, and two quarts of water had been drunk in the interval. The blood will not receive more than a certain amount; and as an over-amount of salt will produce extreme thirst, a quantity passes through the kidneys with the water that has been drunk; frequent drinking of course causes frequent micturition. If we take the mean of numerous observations by several The quantity of the chloride of sodium in the blood is liable to great variation in different diseases; and there can be little doubt that this variation is closely connected (though whether in the relation of cause or in that of effect, we are not exactly entitled to surmise) with the histological and other transformations of the component parts of the blood. The proportions of salt greatly differ in several tissues, and also at different periods of the development of the same tissue. “Thus in muscle,” according to Enderlin, “100 parts of the ash left after incineration of ox-flesh yielded nearly 46 per cent. of the chloride of sodium and potassium; which, as this ash constitutes 4·23 per cent. of the dried flesh, would give 1·94 as the proportion of the chloride of sodium in 100 parts of the latter; and reckoning this dried residue to constitute 28 per cent. of the whole substance of the muscle (the remaining 77 parts being water) the proportion of chloride of sodium in the latter will be 0·44. These figures, as will be presently seen, bear a remarkably close correspondence to those which represent the proportion of chloride of sodium in the ash, solid residue and entire mass of the blood.” Next to muscle, cartilage contains the largest amount of the chloride of sodium, and this especially in the temporary cartilages of the foetus, its place being taken by the phosphate of lime as it approaches the time of birth. The percentage of the chloride of sodium contained in the ash of the costal cartilage of an adult is about 8·2; in the laryngeal cartilage 11·2; but as the ash does not constitute above 3·4 per cent. of the entire substance the percentage of the chloride of sodium in the latter is, at the most, 0·38 of the whole, or less than that of blood and muscle. Only from 0·7 to 1·5 per cent. could be extracted from the ash of bone. Besides the important uses of the chloride of sodium in the blood to which we have already adverted, it serves the purpose of furnishing the hydrochloric acid required (by many animals, at least) for the gastric secretion; and it likewise supplies the soda-base for the alkaline phosphate, whose presence in the blood appears Percentage of Chloride of Sodium in various Animal Fluids, their Solid Residue and their Ash.
We have thus proved physiologically that the chloride of sodium holds a most prominent position among the other constituents of the body; that it is present in considerable quantities in muscle as well as in the blood; and that it furnishes the acid, which is necessary for the stomach to perform its functions of digestion. It holds the albumen partly in solution, and its coagulation is dependent more or less on the amount of salt which is present in the blood, and it also possesses the power of preventing the coagulation of the fibrine. In fevers the blood is generally thicker, and has a tendency to coagulate by reason of the partial absence of salt, because a good deal passes off with the perspiration; and fever patients always prefer salt to sugar, for while one refreshes them and helps to restore the usual healthy tone of the palate, by constringing the papillÆ of the tongue, the other raises feelings of disgust. It is also present in cartilage, though in a lesser degree than in blood or muscle, because in cartilage there is no disintegration or In febrile disease the fibrine of the blood is materially increased, and there is also a marked decrease of salt, which is dependent on a greater or lesser intensity of the attack, rendering the blood denser, owing to the fact of the tendency of the fibrine to coagulate by reason of the diminution of the chloride of sodium, causing the blood to circulate slowly and with difficulty. In some other morbid conditions, which we have already noticed, the blood becomes thinner and poorer; and consequently the system degenerates, and we get an anÆmic, or chlorotic tendency, especially if there is a scrofulous diathesis. There are other blood diseases, as the reader may suppose, and which are more truly such, than those to which I have just alluded, into the phenomena of which it is not necessary to enter. In health what a decided difference! the specific gravity of the blood is uniformly equable; What stronger evidence do we require to prove the salutary efficacy of salt? No wonder that it is so frequently reverted to in Holy Writ; neither can it be a source of surprise that it has been so carefully cherished and extensively utilised from time immemorial. What is to be regarded as an extraordinary anomaly is that there are not a few who are entire strangers to its virtues, Those who desire more conclusive proof of the utility of salt, of its necessity in the animal economy, and of the peculiar morbid phenomena to which its absence in the system gives rise, I would refer to two articles which appeared at different times in the Medical Press and Circular, and in the Medical Times and Gazette. |