PHILOSOPHERS

OF

THE TIME OF GEORGE III.

BLACK.

THE physical sciences have few more illustrious names to boast than that of Joseph Black. With all the habits and the disciplined faculties of a true philosopher, with the temper as well as the capacity of a sage, he possessed that happy union of strong but disciplined imagination, with powers of close undivided attention, and ample resources of reasoning, which forms original genius in scientific pursuits; and, as all these qualities may be combined in an individual without his happening to signalise his investigations of nature by any discovery, we must add that his life was crowned with the good fortune of opening to mankind new paths in which both himself and his followers successfully trod, enlarging to an incalculable extent the bounds of human knowledge. The modesty of his nature making him averse to publish his speculations, and the genuine devotion to the investigation of truth, for its own sake, rendering him most open in his communications with all who were engaged in the same pursuits, his incontestable claim to be regarded as the founder of modern chemistry has been oftentimes overlooked; and, while some have endeavoured more or less obscurely to mingle themselves with his discoveries, others have thought it becoming to post-date the new

B

system, that it might seem the produce of a somewhat later age. The interests of truth and justice therefore require that we should minutely examine the facts of the case; and, happily, the evidence is so clear that it only requires an attentive consideration to remove all doubt from the subject. I feel it a duty imperatively cast upon me to undertake a task from which, did I not regard it as less difficult than sacred, I might shrink. But I had the great happiness of being taught by himself, having attended one of the last courses of lectures which he delivered; and the knowledge thus gained cannot be turned to a better use than in recording the glory and in vindicating the fame of my illustrious

master.

The story of a philosopher's life is soon told. Black was born, in 1721, at Bordeaux, where his father, a native of Belfast, was settled as a merchant: he was, however, a Scotchman, and his wife too was of a Scottish family, that of Gordon of Hillhead, in Aberdeenshire, settled like Mr. Black at Bordeaux. The latter was a person of extraordinary virtues, and a most amiable disposition. The celebrated Montesquieu honoured him with his especial regard; and his son preserved, as titles of honour in his family, the many letters of the President to his parent. In one of them he laments the intended removal of the Black family as a thing he could not reconcile himself to, for his greatest pleasure was seeing them often, and living himself in their society. Though Mr. Black sent his son, at the age of twelve, for some years to a school in Ireland, he was removed to the College of Glasgow in the year 1746, and ever after lived in that which was, properly speaking, his native country. At that college he studied under the celebrated Cullen, then Professor of Anatomy and Lecturer on Chemistry; and, having removed in 1750 to Edinburgh for the benefit of that famous medical school, he took his degree there in 1754. In 1756 he was appointed to succeed Dr.

Cullen in the chair of anatomy and chemistry at Glasgow, and he continued to teach there for ten years, when he was appointed to the chemistry professorship at Edinburgh. He then lectured for thirty years to numerous classes, and retiring in 1796 lived till 1799, and died on the 26th of November in that year. His health never was robust; it was indeed precarious at all times from a weakness in the bronchia and chest, but he prolonged life by a system of the strictest abstinence, frequently subsisting for days together on watergruel and diluted milk. He never was married; but he cherished with unvarying affection his near relatives, who well deserved his care. His favourite niece, Miss Burnet, a person of great sense and amiable temper, was married to his friend and second cousin, Professor Ferguson, the historian and moral philosopher. Dr. Black lived in a select circle of friends, the most illustrious men of the times in science and in letters, Watt, Hutton, Hume, Robertson, Smith, and afterwards with the succeeding generation of Scottish worthies, Robison, Playfair, Stewart. Delighting to commune, to speculate, and to investigate with them, he was careless of the fame which however he could not but be sensible his labours must achieve. He was extremely averse to publication, contemning the impatience with which so many men of science hurry to the press, often while their speculations are crude, and their inquiries not finished. Nor could the reason often urged in defence of this find much favour with one who seemed never to regard the being anticipated by his fellowlabourers as any very serious evil, so the progress of science was secured. Except two papers, one in the 'London Philosophical Transactions' for 1775 on the freezing of boiled water; the other, in the second volume of the Edinburgh Transactions,' on the Iceland hot springs; he never published any work after that of which we are now to speak, in 1755, and which, but for the accidental occasion that gave rise to it,

would possibly, like his other original speculations, never have been given by himself to the press.

Upon taking his degree at Edinburgh College he wrote and published a Latin Thesis, after the manner of that as well as the foreign universities. The subject was 'Magnesia, and the Acid produced by Food in the Stomach (De Acido e Cibis orto; et de Magnesia), and it contained the outline of his discoveries already made. Having sent some copies of this Thesis to his father at Bordeaux, one was given to Montesquieu, who at once saw the vast importance of the truths which it unfolded. He called a few days after and said to Mr. Black, “I rejoice with you, my very good friend: your son will be the honour of your name and of your family." But though the discoveries were sketched distinctly enough in this writing, they were only given at large the following year in his celebrated work 'Experiments on Magnesia, Quicklime, and other Alkaline Substances,' incontestably the most beautiful example of strict inductive investigation since the 'Optics' of Sir Isaac Newton. His fervent admiration of that masterly work was indicated by his giving it to Professor Robison, then a student, and desiring him to "make it the model of all his studies," recommending him at the same time a careful study of the mathematics. It appears that this important inquiry concerning the alkaline earths, the results of which were destined to change the face of chemical science, was suggested by the attempts then making to find a solvent for the stone. I distinctly recollect Dr. Black, in his lectures, prefacing the admirable and most interesting account which he gave of his discoveries, with the statement that the hopes of finding a solvent which should not, like the caustic alkalies, destroy the substance of the bladder in melting the stone, first led him to this investigation. Professor Robison has given a note from his memorandum-book indicating that he had at first fallen into the notion of alkalies, when treated with quicklime,

deriving from it their caustic quality; the common belief (which gave rise to the term caustic) being that lime obtained from the fire the quality of growing extremely hot, even to ignition when united with water. But experiment soon corrected this idea; for, having exposed the caustic or quicklime to the air till it became mild, he says, "Nothing escapes (meaning no fire or heat); the cup rises considerably by absorbing air." Another observation on the comparative loss of weight sustained by chalk when calcined (in the fire), and when dissolved in an acid, is followed by the account of a medical case, which the Professor knew to have occurred in 1752. A third note follows, and proves him to have now become possessed of the true theory of causticity, namely, the expulsion of air, and of mildness, namely, its absorption. The discovery was therefore made as early as 1752-it was published generally in 1754-it was given in its fullest details in 1755. At this time M. Lavoisier was a boy at school -nine years old when the discovery was made-eleven when it was published-twelve when it was as fully given to the world as its author ever delivered it. No possibility therefore existed of that great man finding out when he composed his great work that it was a discovery of his own, as he did not scruple to describe oxygen, though Dr. Priestley had first communicated it to him in the year 1774; or that Black and he discovered it about the same time, as he was in the habit of stating with respect to other gases, with a convenient degree of ambiguity just sufficient for self-defence, should he be charged with unfair appropriation. Who that reflects on the noble part which this great philosopher acted, both in his life and in his death, can avoid lamenting that he did not rest satisfied with the fame really his due, of applying the discoveries in which he had no kind of share, to the investigation of scientific truths, as entirely the result of his extraordinary faculty of generalization, and genius for philosophical