Page:A biographical dictionary of eminent Scotsmen, vol 9.djvu/303

Rh by the Professor of Logic in Edinburgh, as an admirable example of the analytic and synthetic methods. Previous to the publication of his "System," British chemists were contented with translations from the French; and hence it was believed on the Continent that "Britain possessed scarcely a scientific chemist." That all his contemporaries viewed his plan as highly philosophic cannot be affirmed. There are some men who, having no mental powers of arrangement in themselves, discover in a systematic treatise only a compilation possessing the generic characters of matter; while those who can pry below the surface, on the other hand, know that the art of arranging is one of the most difficult tasks of the philosopher; that it requires a comprehensiveness of mind, a clearness of judgment, and a patience of labour, which fall to the lot of a small number of the human race. When we recollect that many of these remarkable views began to be devised by the self-taught chemist, in a narrow close in the High Street of Edinburgh, the author being in the receipt of a salary of 50 a-year, from which he sent 15 to his aged parents; and when we contrast such a picture with the costly education and refined apparatus of the modern laboratory, it is impossible to avoid the inference, that in Dr. Thomson Britain possessed a genius of no common order.

One immediate result of the publication of his "System" was the appropriation of their due merit to respective discoverers, and especially to British chemists, who had been overlooked in the Continental treatises. It was the subject of our memoir who thus first imparted to us the true history of chemistry, and in doing so often gave offence to disappointed individuals; but the honesty of his nature and his unswerving love of truth never allowed him for a moment to sacrifice, even in his own case, the fact to the fallacy.

During the first years of this century, he discovered many new compounds and minerals, as chloride of sulphur, allanite, sodalite, &c.; but to give a list of the numerous salts which he first formed and described during his onward career would be difficult, as he scarcely ever treated of them in separate papers, but introduced them into the body of his "System," without any claim to their discovery. His exact mind was more directed towards accurate knowledge and principles, than to novelties merely for their own sake, although there is probably no chemist who has added so many new bodies to the science. Hence, many of his discoveries have been attributed to others, or re-discovered over and over again, as was the case with many of his chromium compounds—viz., chlorochromic acid, the two potash oxalates of chromium, bichromate of silver, potash chromate of magnesia, chromate of chromium, hyposulphurous acid (1817), and hydrosulphurous acid (1818), S5 O5, &c., all of which were examined by him above a quarter of a century ago.

In 1810, Dr. Thomson published his "Elements of Chemistry," in a single volume, his object being to furnish an accurate outline of the actual state of the science. In 1812 he produced his "History of the Royal Society," a most important work, as showing the influence which that society produced on the progress of science. In August, 1812, he made a tour in Sweden, and published his observations on that country in the following year. It is still a valuable work, and contains a very complete view of the state of science and society in Sweden. In 1813 he went to London, and started the "Annals of Philosophy," a periodical which he continued to conduct till 1822, when the numerous calls upon his time in the discharge of the duties of his chair at Glasgow, compelled him to resign the editorship in favour of Mr. Richard