xin THE DECOMPOSITION OF THE ALKALIS 265 



He made many attempts to prepare oxygen from nitrogen or 

 water from ammonia, but concluded at last that these could 

 not be produced from the pure dry gases. The presence of 

 oxygen in nitrogen was, however, accepted by Berzelius up 

 to about 1820, both chlorine and nitrogen being tabulated 

 as oxides in his essay on "Chemical Proportions "in 1819. 

 Davy (1812) also suspected the presence of hydrogen in 

 sulphur and phosphorus and, by analogy, in inflammable 

 substances and metals generally (Works, IV. 358-359). 

 These tentative hypotheses are of interest as showing the 

 great difficulty of establishing the elementary character of 

 any given substance. 



Seebeck (1808) prepares an amalgam from ammonia. 

 Davy's views as to the composition of ammonia led him to 

 attach great importance to the discovery of a metallic 

 amalgam prepared from it by the action of an electric 

 current. Berzelius and Hisinger had found (Ann. de Chimie, 

 1804, 51, 167) that concentrated aqueous ammonia was 

 decomposed into nitrogen and hydrogen by passing an electric 

 current through it, between platinum wires. Seebeck at 

 Jena and Berzelius and Pontin (Gilbert's Annahn, 1810, 6, 

 247-280) at Stockholm, discovered early in 1808 that an 

 amalgam was produced, instead of hydrogen, when mercury 

 was substituted for platinum. The amalgam was examined 

 immediately by Davy, who included a section " On the 

 production of an Amalgam from Ammonia " ( Works, V. 

 122) in a paper on the Decomposition of the Earths, read 

 before the Royal Society on June 30, 1808. Davy describes 

 its preparation and properties as follows : 



" When a globule of pure mercury is negatively electrified 

 by a Voltaic apparatus of 100 pairs of plates, it being in 

 contact with solution of ammonia in a cavity made in a 

 piece of muriate of ammonia, or any ammoniacal salt, 

 moistened in such a manner, and so placed on a disc of 

 platina, that the circuit is completed ; the globule increases 



