C 571 ) 



ANALYSIS OP BOOKS, AND SELECTIONS FROM THE 

 TRANSACTIONS OF SCIENTIFIC SOCIETIES. 



The Life of Sir Humphry Davy, Bart., LL.D., late President of 

 the Royal Society, Sfc. fyc. fyc. By John Ayrton Paris, M.D., 

 F.R.S., &c. &c. 4to. London, 1831. 



(Concluded from p. 360.) 



TN the year 1808, MM. Gay-Lussac and Thenard succeeded in 

 decomposing potash by chemical means ; and Davy soon repeated 

 their experiment. This process afforded the means of procuring 

 potassium more readily in larger quantities than by means of voltaic 

 electricity. The facility of the combustion of the alkalies, and the 

 readiness with which they decomposed water, offered Davy the 

 ready means for determining the proportions of their constituent 

 parts : he thought potash composed of about six parts base and one 

 of oxygen ; and soda, as consisting of seven parts base and two of 

 oxygen. The over-excitement and fatigue of his researches upon 

 this occasion, and the irregularity of his habits, threw him into a 

 fever. Such was the alarming state of his disorder, that for many 

 weeks his physicians visited him four times a-day. 



The course of lectures on Electro-Chemical Science, which 

 he gave on his recovery, commenced in March, 1808, and the 

 theatre of the Institution overflowed with admiring and interested 

 auditors. At the same period he gave a course in the evening 

 on Geology, which was equally attractive. Having succeeded in 

 decomposing the alkalies, it was natural that he should turn his 

 attention to the earths; he, however, found them much more 

 difficult to conquer. While busily engaged in pursuit of his object, 

 he received a letter from Professor Berzelius, of Stockholm, 

 announcing that, in conjunction with Dr. Pontin, he had succeeded 

 in decomposing baryta and lime by negatively electrising mercury 

 in contact with them, and by such means had actually obtained 

 amalgams of these earths. Davy immediately repeated the experi- 

 ments with success; and having, by additional experiments, fully 

 established the nature of these bodies and the analogies he had 

 anticipated, he published the result in a memoir to the Royal 

 Society in June, 1808, entitled 4 Electro-Chemical Researches on 

 the Decomposition of the Earths ; with Observations on the Metals 

 obtained from them, and on the Amalgam of Ammonia.' 



It has, however, been doubted whether the change, which am- 

 monia and mercury undergo by voltaic action, merits the name of 

 amalgamation, and whether it may not be referred to a purely me- 

 chanical cause ; and Dr. Paris observes, in a note, that this opinion 

 is strongly confirmed by Mr. Daniell's paper * On certain Pheno- 

 mena resulting from the action of Mercury upon different Metals/ 

 published in the first number of this Journal. 



