Davy, who was at this time only nineteen years of age, should suspend his plan of going to Edinburgh, and take a part in experiments which were then about to be instituted at Bristol, for investigating the medical powers of factitious airs; to this proposal Mr. Davy consented, on condition that he should have the uncontrolled superintendence of the expements. About this time he became acquainted with Davies Gilbert, Esq. M.P. a gentleman of high scientific attainments, (now President of the Royal Society), with whom he formed a friendship which has always continued; and to Mr. Gilbert's judicious advice may be attributed Mr. Davy's adoption of and perseverance in the study of chemistry. With Dr. Beddoes, Mr. Davy resided for a considerable time, and was constantly occupied in new chemical investigations. Here, he discovered the respirability of nitrous oxide, and made a number of laborious experiments on gaseous bodies, which he afterwards published in "Researches Chemical and Philosophical," a work that was universally well received by the chemical world, and created a high reputation for its author, at that time only twenty-one years of age. This led to his introduction to Count Rumford, and to his being elected Professor of Chemistry to the Royal Institution in Albemarle-street. On obtaining this appointment Mr. Davy gave up all his views of the medical profession, and devoted himself entirely to chemistry. Mr. Davy's first experiments as Professor of Chemistry in the Royal Institution, were made on the substance employed in the process of tanning, with others to which similar properties were ascribed, in consequence of the discovery made by M. Seguier, of Paris, of the peculiar vegetable matter, now called tannin. He was, during the same period, frequently occupied in experiments on galvanism. To the agriculturist, chemistry is of the first consideration. The dependence of agriculture upon chemical causes had been previously noticed, but it was first completely demonstrated in a course of lectures before the Board of Agriculture, which Mr. Davy commenced in the year 1802, and continued for ten years. This series of lectures contained much popular and practical information, and belongs to the most useful of Mr. Davy's scientific labours; for the application of chemistry to agriculture is one of its most important results; and so rapid were the discoveries of the author, that in preparing these discourses for publication, a few years afterwards, he was under the necessity of making several alterations, to adapt them to the improved state of chemical knowledge, which his own labours had, in that short time, produced.