76 HISTORY OF CHEMISTRY. [LECTURE V. 



assumes the existence of oxygen in hydrochloric acid, and, in 

 \ opposition to the experiments of Berthollet, 24 advances the 

 opinion that ammonia is also an oxygen compound. 25 He 

 suspects the presence of oxygen in silicic acid, which he tries to 

 reduce ; 26 in the earths, which, as we know, he succeeded in 

 reducing ; 2T finally also in phosphorus and sulphur, 28 a view 

 which was refuted by Gay-Lussac and Thenard. 29 



Some time afterwards, when engaged upon the investigation 

 of ammonium amalgam 30 (which had been discovered shortly 

 before by Seebeck 31 and more minutely studied by Berzelius 

 and Pontin 32 ), he finds its behaviour to be analogous to that 

 of the other amalgams, and assumes that it is produced by the 

 combination of mercury with a hypothetical substance, am- 

 monium, resembling the metals, and itself containing hydrogen 

 and ammonia. In comparing now this ammonium with the 

 metals, he is led to ascribe a similarity of constitution to both ; 

 that is, he assumes the existence of hydrogen in the metals also, 

 whereby their combustibility could be explained. Davy states 

 this as a possibility, which he most correctly recognises as 

 identical with Cavendish's phlogiston theory, and which he 

 naturally extends to potassium and sodium. 



Gay-Lussac and Thenard arrived almost simultaneously at 

 the same view. 33 They had investigated the action of potas- 

 sium on ammonia gas, and, in doing so, had observed the 

 formation of a green substance (potassamide), with simultaneous 

 evolution of hydrogen. In these experiments, which they 

 carried out quantitatively, they found the quantity of hydrogen 

 evolved to be identical with that which the quantity of potas- 

 sium employed would have liberated from water. They further 

 showed that, in addition to the formation of potash, the whole 



24 Mem. de 1'Acad. 1785, 324 ; Stat. Chim. 2, 280; E. 2, 238. w Phil. 

 Trans. 1808, 35; A.C.R. 6, 37. 26 Phil. Trans. 1810, 59. 27 Ibid. 1810, 

 16, 62, etc. 28 Ibid. 1809, 67, etc ; Ann. Chim. 76, 145. M Recherches 

 physico-chimiques. I, 187. 30 Phil. Trans. 1810, 37. 31 Gehlen's 



Journal fiir die Chemie, etc., 5, 482. 32 Bibliotheque Britannique (1809), 

 122, Nos. 323 and 324; Gilb. Ann. 36 (1810), 261. 33 Ann. Chim. 



66, 205. 



