xv THE MOLECULAR THEORY 331 



were exploded with 300 parts of hydrogen and produced a 

 diminution of 2987 parts by volume. In these experiments 

 99*6 parts of oxygen united with 298*7-99'6 = 199*1 parts of 

 hydrogen, or TOO parts of oxygen united with 199*89 parts 

 of hydrogen, a number that did not differ appreciably from 

 (that required for the exact integral ratio i : 2 (loc. tit. pp. 

 146147). 



Gay-Lussac (1809) states that gases combine in simple 

 proportions by volume. (i) The combination of ammonia 

 with acids. This simple relationship between the combining 

 volumes of hydrogen and oxygen was in such striking 

 contrast with the complex ratio of the combining weights 

 that Gay-Lussac in 1809 (A.C.R. IV. 8-24) preceded to 

 examine the ratios of the combining volumes of other gases. 

 As the simplest case he studied first the combination of 

 ammonia with acid gases, including muriatic acid gas and 

 carbonic anhydride. He found that : 



" 100 parts of muriatic gas saturate precisely 100 parts of 

 ammonia gas, and the salt which is formed from them is 

 perfectly neutral, whether one or other of the gases is in 

 excess." " If carbonic gas is brought into contact with 

 ammonia gas, by passing it sometimes first, sometimes 

 second into the tube, there is always formed a sub-carbonate 

 composed of 100 parts of carbonic gas, and 200 of ammonia 

 gas" (A.CR. IV. 10). 



(2) Composition by volume of ammonia, sulphuric acid and 

 carbonic anhydride. Equally simple relationships were 

 found to govern the proportions of nitrogen and hydrogen 

 in ammonia gas, of " sulphurous gas " and oxygen in 

 sulphuric anhydride, and of the carbonic oxide and oxygen 

 in carbonic anhydride. 



" According to the experiments of M. Ame'dee Berthollet, 

 ammonia is composed of: 



100 of nitrogen, 

 300 of hydrogen 

 by volume. 



