33 On the Daltonian Theory of [July, 



3. When three combinations are observed, we may expect 

 one to be binary, and the other two ternary. 



4th. When four combinations are observed, we should expect 

 one binary, two ternary, and one quaternary, &c. 



5th, A binary compound should always be specifically heavier 

 than the mere mixture of its two ingredients. 



6th. A ternary compound should be specifically heavier than 

 the mixture of a binary and a simple, which would, if com- 

 bined, constitute it, &c. 



7th. The above rules and observations equally apply, when two 

 bodies, such as C and D, D and E, &c. are combined.'* 



If the observations of Gay-Lussac be correct, nitrous gas 

 constitutes an exception to Mr. Dalton's 5th rule. It will come 

 under our examination hereafter. 



II. Chemical Canons founded on the above Theory, but deduced 



from Analysis. 



1. When gaseous bodies combine they always unite in deter- 

 minate proportions; and if we represent the bulk of the gas that 

 enters into the compound in the smallest quantity in bulk by 1, 

 then the bulk of the other constituent is either 1, 2, or 3. 

 Thus muriate of ammonia is composed of 1 muriatic acid + 1 

 ammonia in bulk ; carbonate of ammonia, of 1 carbonic acid 

 -f- 1 ammonia; nitrous gas, of 1 azote + 1 oxygen ; water, of 

 1 oxygen + 2 hydrogen ; gaseous oxide of azote, of 1 oxygen 

 + 2 azote; nitrous acid, of 1 azote + 2 oxygen, or of 1 

 oxygen + 2 nitrous gas ; sulphuric acid, of 1 oxygen + 2 

 sulphurous acid ; carbonic acid, of 1 oxygen + 2 oxide of 

 carbon ; ammonia, of 1 azote + 3 hydrogen ; nitrous acid gas, 

 of 1 oxygen + 3 nitrous gas. This canon has been established 

 by Gay-Lussac, I think, in a satisfactory manner. f The only 

 one of his conclusions which is still doubtful is that nitrous acid 

 is a compound of 2 nitrous gas + 1 oxygen gas. At least I 

 have not been able to make the two gases unite exactly in that 

 proportion. This canon is obviously connected with the Dai- 

 toman theory. It is simple and beautiful, and of considerable 

 utility in practical chemistry. 



2. The quantity of acid requisite to saturate the different 

 metals is directly as the quantity of oxygen which these metals 

 require to convert them into oxides. Thus 100 parts of mercury 

 require 4 - lC parts of oxygen, and 100 parts of silver require 

 7*9 parts of oxygen, to convert them into oxides. Therefore 

 the quantity of acid necessary to saturate 100 parts of mercury 



* Dalton's New System of Chemistry, vol. i. p.,214. 

 + Mem. d'Arcueil, vol. ii. p. 207. 



