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TOCINX

At the period when Watt, having connected himself in partnership with Boulton, went to reside at Soho, near Birmingham, a number of persons, some of whom have since attained great celebrity by their discoveries and their works, and all of whom were devoted to inquiries connected with the arts and sciences, resided in that neighbourhood. Among these may be mentioned Priestley, whose discoveries in physical science have rendered his name immortal; Darwin, the philosopher and poet; Withering, a distinguished physician and botanist; Keir, a chemist, who published a translation of Macquer, with annotations; Galton, the ornithologist; and Edgeworth, whose investigations respecting wheeled carriages and other subjects, have rendered him well known. A society was formed by these and other individuals, of which Boulton and Watt were leading members, the meetings of which were held monthly on the evening of full moon, and which was thence called the Lunar Society. At the meetings of this society, subjects connected with the arts and sciences were discussed, and out of those discussions occasionally arose suggestions not unattended with important and advantageous consequences. At one of these meetings, Darwin stated that he had discovered a pen formed with two quills, by means of which, at a single operation, an original and a copy of a letter might be produced. Watt almost instantly observed that he thought he could find a better expedient, and that he would turn it in his mind that night. By the next morning the COPYING PRESS was invented, for which he afterwards obtained a patent.

This machine, which is now so generally used in counting-houses, consists of a rolling-press, by which a leaf of thin paper, previously damped, is pressed upon the letter to be copied. The writing, of which the ink is not yet quite dry, leaves its impression upon the thin paper thus pressed upon [Pg303] it, and the copy taken in this manner is read through the semi-transparent paper. If a letter be written with ink suitable for this purpose, a copy may be taken at any time within several hours after the letter is written.

The method of heating apartments and buildings by steam, which has since been improved and brought into extensive use, was likewise brought forward by Watt. Although this contrivance had been previously pointed out by Sir Hugh Platt about the middle of the seventeenth century, and by Colonel Cooke in 1745, yet these suggestions remained barren. Mr. Watt gave detailed methods of heating buildings by steam[25]; and also invented a machine for drying linen by steam, a description of which he communicated to Dr. Brewster, which was read in December, 1824, before the Society for promoting Useful Arts in Scotland.[26]

But the circumstance, exclusive of those connected with the invention of the steam engine, which is by far the most memorable in the career of Watt, is the share which he had in the discovery of the composition of water. As this circumstance has recently excited much interest, and led to some controversy, we shall here state, as distinctly as possible, the leading facts connected with it.

Water, which was so long held to be a simple element, has, in modern times, been proved to be a substance consisting of two aeriform bodies or gases chemically combined. These two gases are those called in chemistry oxygen and hydrogen. If eight grains weight of oxygen be mixed with one grain weight of hydrogen, and the mixture be submitted to such effects as would cause the chemical combination of these two airs, it would be converted into nine grains weight of pure water.

If, on the other hand, nine grains weight of pure water be submitted to any conditions which would separate its constituent parts, the result would be eight grains weight of oxygen gas, and one grain weight of hydrogen gas. There are a variety of methods in physics by which these effects would be [Pg304] produced. It will be sufficient here to state one method of producing each of the above changes.

If eight grains weight of oxygen be inclosed in a strong vessel with one grain weight of hydrogen, all other substances being excluded, and the mixture be inflamed, an explosion will take place, the gases will disappear, and a small quantity of water will be the only substance remaining in the vessel. If this water be weighed, it will be found to weigh exactly nine grains.

It is known that the metals have a strong attraction for oxygen gas, and this attraction is promoted by elevating their temperature. If a glass tube be filled with iron wire heated to redness, and to one end of this tube a small vessel of boiling water be attached, the steam evolved from the water will force its way through the spaces between the red-hot wires in the tube, and would be expected to issue from the remote end; but if the substance issuing from the remote end of the tube be examined, it will be found to be not steam, but hydrogen gas. If the quantity of this gas be ascertained by weight, and also the quantity of weight lost by the vessel of water at the other end of the tube, it will be found that the loss of weight of the water by evaporation will be nine times the weight of the hydrogen which has issued from the remote end of the tube. If the weight of the tube with the wire contained in it be next ascertained, it will be found to be increased by eight times the weight of the hydrogen which has issued from its remote end. From this it follows that the weight of the hydrogen which has escaped from the tube, added to the increase of weight which has been given to the wire in the tube, makes up the whole weight of the water evaporated. If the wire in the tube be next examined, it will be found that it has suffered oxydation, or, in other words, that a new substance has been formed in it called the oxyde of iron,—such substance being a chemical compound formed of oxygen gas and iron.

It follows, therefore, that in this process the vapour of the water, in passing through the tube, has been decomposed, and that, having given up to the iron its oxygen, the hydrogen [Pg305] alone escaped from the other end; and for every nine grains weight of steam which passed through the tube, eight grains of oxygen have been combined with the iron, and one grain of hydrogen has escaped from the end of the tube.

Such are the class of effects on which the modern discovery of the composition of water has been based. The merit of that discovery has been shared between the celebrated English chemist, Cavendish, and the not less celebrated French chemist, Lavoisier, the chief merit, however, being ascribed to the former.

We shall now briefly state the facts which led to this discovery, with their dates, which will necessarily show the share which Watt had in it.

When pure hydrogen gas is burned in an atmosphere of common air, the process which takes place is now known to be nothing more than the chemical combination of the hydrogen with eight times its own weight of oxygen taken from the atmosphere, and the product of the combustion is a quantity of water nine times the weight of the hydrogen consumed. In the year 1776, Macquer, a well-known chemist of that day, having held a saucer of white porcelain over a flame of hydrogen which was burning at the mouth of a bottle, observed that no smoke was produced and no soot deposited on the saucer. On the other hand, he found that after the lapse of some time drops of a clear pellucid liquid were perceptible on the saucer: this liquid he submitted to analysis, and found it to be pure water. Macquer mentioned this fact without comment or inference. It did not occur to him that the water thus produced upon the saucer was a substance which contained the hydrogen, which disappeared upon combustion from the bottle.

On the 18th of April, 1781, Mr. Warltire addressed a letter to Dr. Priestley, dated Birmingham, which letter is published in Dr. Priestley's Experiments on Air, printed at Birmingham in 1781, in which Warltire informs Priestley that he had fired a mixture of hydrogen and common air in close glass vessels, and that, although previously to firing the mixture the vessels were clean and dry, a dewy deposit was [Pg306] observed afterwards on their sides. In fact, water was present which was not present before.

The mixture was in this case fired by passing an electric spark through the vessel; and it is now known that the effect produced was the combination of the hydrogen, which formed part of the mixture of airs in the vessel with the oxygen, which also formed part of the same mixture.

It appears, from expressions in Warltire's letter, that the same experiment had been previously made by Priestley, and the same result observed by him.

The inference deduced from this by Warltire, and apparently acquiesced in by Priestley, was, that whenever hydrogen was fired in atmospheric air, the moisture, which is always more or less sustained in the latter, was deposited; but neither of these chemists perceived the real cause of the production of the water.

In the beginning of 1783, and not later than the 21st of April, this experiment of Warltire and Priestley was repeated by Cavendish, with this difference, that, instead of exploding the mixture of hydrogen and common air, Cavendish exploded a mixture of hydrogen and oxygen. He observed that water was present after the explosion, but inferred nothing.

In a published paper dated April, 1783, Priestley announced a further and most important result of his experiments. This was, that in examining the weight of water produced by the explosion of a mixture of oxygen and hydrogen, that weight was found to be precisely equal to the sum of the weights of the two gases, which disappeared in the process.

Immediately on observing this, Priestley, being then, as has been already stated, Watt's near neighbour, communicated to the latter what he had observed; upon which Watt immediately, viz. by a letter dated the 26th of the same month, declared that the inevitable consequence which followed from Priestley's observations was, that water was a substance compounded of oxygen and hydrogen deprived of [Pg307] a quantity of heat which was previously latent in them.[27] The letter containing this inference was communicated immediately by Priestley to Sir Joseph Banks, then President of the Royal Society, to be laid before that body; and it is accordingly printed with its proper date in the 74th volume of the Philosophical Transactions.

About two months after the date of Mr. Watt's letter just quoted, Lavoisier made experiments on the combustion of oxygen and hydrogen, and read a memoir before the Academy of Sciences in Paris, in which his views of the formation of water by the combination of these gases were developed. This paper, by Lavoisier, was afterwards printed in the Memoirs of the Academy in the year 1784. The experiments are there stated to have been made in the month of June, 1783; and it is stated that Sir Charles Blagden, who was present at the experiments, told Lavoisier that Mr. Cavendish had already burned the same gases in close vessels, and obtained a very sensible quantity of water.

On the 15th of January, 1784, the celebrated paper by Cavendish, entitled "Experiments on Air," was read before the Royal Society, and in this paper the composition of water by the union of oxygen and hydrogen is explained.

In a controversy which afterwards ensued on the respective [Pg308] claims of Cavendish and Lavoisier to credit for the discovery of the composition of water, Sir Charles Blagden stated that he had told Lavoisier, in June, 1783, more than Lavoisier acknowledged, that he had not only told him that water was produced by the combustion of the gases, but that his information embraced the whole theory of the composition of water. This declaration of Blagden was subsequent in date to January, 1784, and there is no evidence of any explanation of this theory, verbal or otherwise, having been given by Cavendish, or any other person, antecedent to April, 1783.

From this brief statement of the facts and dates it will appear that the merit of the discovery of the FACT, that the weight of water resulting from the combustion of oxygen and hydrogen, is equal to the sum of the weights of the oxygen and hydrogen which disappear in the combustion, is due to Priestley; and that the merit of the INFERENCE from that fact, that water is a compound body, whose constituents are oxygen and hydrogen, is due to Watt.[28] Whether those who subsequently deduced the same inference, and promulgated the same theory, were or were not informed of Mr. Watt's solution of the phenomenon, or what credit may be due to any person, however eminent, who at any time posterior to Mr. Watt's letter to Priestley, asserted that they had, at a time antecedently to that, made the same inference without having published it, or communicated it in such a manner as to establish their claim upon rational and credible evidence, are questions which we shall not here discuss, being contented with establishing the right of Mr. Watt to the merit of the discovery of the THEORY which explained the FACT discovered by Priestley.

Even in his declining years, after he had withdrawn from the active pursuits of his business, the least excitement was sufficient to call into play the slumbering powers of his inventive genius. No object could present itself to his notice [Pg309] without receiving from that genius adaptation in form and construction to useful purposes. As an example of this restless activity of mind the following anecdote may be mentioned:—

A company at Glasgow had erected on the right bank of the Clyde extensive buildings and powerful engines for supplying water to the town. After this expense it was found that a source of water, of very superior quality, existed on the left bank of the river. To change the site of the establishment, after the expense which had been incurred in its erection could not be contemplated, and they therefore proposed to carry across the bottom of the river a flexible suction pipe, the mouth of which should terminate in the source from which the pure water was to be derived. This pipe was to be supported by a flooring constructed upon the bed of the river; but it was soon apparent that the construction of such a flooring on a shifting and muddy bottom, full of inequalities, and under several feet depth of water would require a greater expenditure of capital than could with propriety be afforded. In this difficulty the aged mechanician, for whom Glasgow itself had been the earliest stage of professional labour, was applied to, and instantly solved the problem. His attention is said to have been attracted by a lobster which had been served at table: he set himself about to contrive how, by mechanism, he could make an apparatus of iron with joints which should have all the flexibility of the tail of the lobster. He therefore proposed that an articulated suction-pipe, capable of accommodating itself to all the inequalities and to the possible changes of the bed of the river, should be carried across it; that this flexible pipe should be two feet in diameter, and one thousand feet in length. This project the company accordingly caused to be executed after the plans and drawings of Watt with the most complete success.[29]

[Pg310] Among the less prominent, though not less useful services rendered by Watt to his country, may be mentioned the introduction of the use of chlorine in bleaching. That invention of Berthollet was introduced into England by Watt after his visit to Paris at the close of the year 1786. He constructed all the necessary apparatus for it, directed its erection, and superintended its first performances. He then left it to his wife's father, Mr. Macgregor, to carry on the processes.

When the properties of the gases began to occupy the attention of chemists, attempts were made to apply them as a means of curing diseases of the lungs. Dr. Beddoes pursued this inquiry with great activity, and established, through the means of private subscription, at Clifton, an institution in which this method of cure was carefully investigated. The Pneumatic Institution (for so it was called) has been rendered celebrated for having at its head Humphry Davy, just then commencing his scientific career. Among its founders was also numbered James Watt. Not content, however, with affording the institution the sanction of his name, he designed and caused to be constructed, at Soho, the apparatus used for making the gases and administering them to the patients.

As the exalted powers of the mind of Watt, unfolded in his numerous mechanical and philosophical inventions and discoveries, have commanded the admiration and respect of his species, the affection and love of his fellow men would not have been less conciliated, had the qualities of his heart, as developed in his private and personal relations, been as well known as the products of his genius.

In the year 1764, Watt being then in the twenty-ninth year of his age, married his cousin, Miss Miller. At this time he had fallen into a state of despondency from his disappointments, which produced a serious attack of nervous illness. The accomplishments and superior understanding, the mildness of temper and goodness of disposition of his wife, soon restored him to health. Of this marriage four children, two sons and two daughters, were the issue. Two of these children died in infancy; another, a daughter, was married to Mr. Miller of Glasgow; and the fourth is the [Pg311] present Mr. James Watt. In September, 1773, while her husband was engaged in the design of the Caledonian canal in the North of Scotland, Mrs. Watt died in child-bed of a fifth child, who was still-born: "Would that I might here transcribe," says M. Arago, "in all their simple beauty, some lines of the journal in which he daily recorded his inmost thoughts, his fears, his hopes! Would that you could see him, after this heavy affliction, pausing on the threshold of that home, where 'His Kind Welcomer' awaited him no more; unable to summon courage to enter those rooms where he was never more to meet 'the Comfort of his Life!' Possibly, so faithful a picture of a very deep sorrow might at last put to silence those obstinate theorists, who, without being struck by the thousands of instances to the contrary, do yet refuse qualities of the heart to every man whose intellect has been fostered by the fertile, sublime, and imperishable truths of the exact sciences!"

After the lapse of some years Watt married Miss Macgregor, a person who is represented to have possessed qualities of mind which rendered her a companion every way suitable to her husband. This lady survived Watt, and died in 1832 at an advanced age. Two children were the issue of this second marriage.

In the year 1800 the extended patent right, which had been granted to Boulton and Watt for their improved engine, expired, and at this time Mr. Watt retired altogether from business. He was succeeded by his two sons, the present Mr. James Watt, and Gregory, one of the children of his second marriage. The works at Soho continued to be conducted by the present Mr. Boulton, the son of the partner of Mr. Watt, and the two Messrs. Watt. In 1804 Gregory Watt died at the age of twenty-seven, of a disease of the chest. This afflicting event was deeply felt by Mr. Watt; but he did not sink under it into that state of despondency in which he has been represented to have fallen by M. Arago. On the contrary, he continued to show the same activity of mind which had characterised his whole [Pg312] life; nor did he lose that interest which he always took in the pursuit of literature and in society. The state of his feelings under this affliction is shown by the following extracts from letters written by him at that time, which have been published by Mr. Muirhead.

"Heathfield, January 26th, 1805.

** "I, perhaps, have said too much to you and Mrs. Campbell on the state of my mind. I, therefore, think it necessary to say that I am not low spirited; and were you here, you would find me as cheerful in the company of my friends as usual; my feelings for the loss of poor Gregory are not passion, but a deep regret that such was his and my lot.

"I know that all men must die, and I submit to the decrees of nature, I hope with due reverence to the Disposer of Events. Yet one stimulus to exertion is taken away, and, somehow or other, I have lost my relish for my usual avocations. Perhaps time may remedy that in some measure; meanwhile, I do not neglect the means of amusement which are in my power."

"Heathfield, April 8th, 1805.

** "It is rather mortifying to see how easily the want of even the best of us is dispensed with in the world; but it is very well it should be so. We here, however, cannot help feeling a terrible blank in our family. When I look at my son's books, his writings and drawings, I always say to myself, where are the mind that conceived these things, and the hands that executed them? In the course of nature, he should have said so of mine; but it was otherwise ordered, and our sorrow is unavailing. As Catullus says:—

"But Catullus was a heathen; let us hope that he (G.) is now rejoicing in another and a better world, free from our cares, griefs, and infirmities. Some one has said, I shall not wholly die; and Gregory's name, his merits and virtues, will live at least as long as those do who knew him. You are not, from this, to conceive that we give way to grief; on the contrary, you will find us as cheerful as we ought to be, and as much disposed to enjoy the friends we have left as ever; but we should approach to brutes if we had no regrets."