332 HISTORICAL INTRODUCTION TO CHEMISTRY CHAP. 



"I have found (ist vol. of the Societe d'Arcueil) that 

 sulphuric acid is composed of : 



100 of sulphurous gas, 

 50 of oxygen gas. 



" When a mixture of 50 parts of oxygen and 100 of 

 carbonic oxide (formed by the distillation of oxide of zinc 

 with strongly calcined charcoal) is inflamed, these two gases 

 are destroyed, and their place taken by 100 parts of carbonic 

 acid gas. Consequently carbonic acid may be considered as 

 being composed of : 



100 of carbonic oxide gas, 



50 of oxygen gas." (A.C.R. IV. 13). 



(3) The oxides of nitrogen. Gay-Lussac next calculated 

 from Davy's analyses the volumes of nitrogen and oxygen 

 which would be obtained from the oxides of nitrogen, if 

 these could be decomposed into their elements, and showed 

 that the volume ratios were again of the very simplest. 



" Davy, from the analysis of various compounds of 

 nitrogen and oxygen, has found the following proportions 

 by weight : 



Nitrogen. Oxygen. 



Nitrous oxide . . . . 63 '30 3670 



Nitrous gas .... 44/05 55'95 



[Nitrogen peroxide] . . . 29-50 70-50 



Reducing these proportions to volumes, we find :- 



Nitrogen. Oxygen. 



Nitrous oxide .... 100 49-5 



Nitrous gas 100 108*9 



[Nitrogen peroxide] . . . 100 204-7 



The first and last of these proportions differ only slightly 

 from 100 to 50, and 100 to 200 ; it is only the second 

 which diverges somewhat from TOO to 100. The difference, 

 however, is not very great, and is such as we might expect 

 in experiments of this sort ; and I have assured myself that it is 

 actually nil. On burning the new combustible substance 

 from potash in 100 parts by volume of nitrous gas, there 



