COMBINING PROPORTIONS. Ill 



Of nitric acid the constituents are one proportion of nitrogen 

 177> an d five of oxygen 500, making together 677? which 

 is the combining proportion of that acid, and is found to 

 unite with 112.5 water, with 503 oxide of zinc, and with 590 

 potash, or with the same quantities of these oxides as combine 

 with 501 sulphuric acid. Carbonic acid is composed of one 

 proportion of carbon 76, and two proportions of oxygen 200, so 

 that its combining number is 2/6', in which proportion it unites 

 with 590 potash, to form the carbonate of potash. The equi- 

 valent quantities of all other acids and bases correspond in like 

 manner with the numbers deducible from their composition. 

 Indeed the law is found to hold in compounds of every class and 

 character, and whether they contain few or many equivalents of 

 their elements. Thus of the vegeto-alkali morphia, which con- 

 tains a large number of equivalents, the combining proportion 

 is the high number 3586, which is the sum of thirty-four pro- 

 portions of carbon 2584, eighteen proportions of hydrogen 225, 

 one proportion of nitrogen 177? and six proportions of oxygen 

 600; 3586 morphia being found to unite with 501 sulphuric 

 acid, or a combining proportion of that acid, to form the sul- 

 phate of morphia. 



Compound bodies likewise unite among themselves in mul- 

 tiples of their combining proportions, as well as in single 

 equivalents. Thus 590 potash combine with 652 chromic acid, 

 and with double that quantity, or 1304 chromic acid, to form 

 the yellow and the red chromates of potash ; the first contain- 

 ing one equivalent, and the second two equivalents of acid, The 

 occurrence of multiple proportions was well illustrated by Dr. 

 Wollaston in the carbonate and bicarbonate of potash. A quan- 

 tity of the latter salt being divided into equal parts, one half was 

 exposed to a red heat, by the effect of which the salt lost some 

 carbonic acid and became neutral carbonate, and both portions 

 being afterwards decomposed by an acid, the salt in its original 

 condition was found to afford a measure of carbonic acid gas 

 exactly the double of that yielded by the portion exposed to 

 the high temperature. By experiments equally simple and 

 convincing, he proved that in the three salts formed by oxalic 

 acid and potash, the quantities of acid which combine with the 

 same quantity of alkali are rigorously among themselves as the 

 numbers 1, 2, and 4. The composition of all other super and 

 sub salts is found to be in conformity with the same law, one of 



