1819.] Acids, Alkalies, and their Compounds. 287 



accordingly strictly conformable to the view I have stated of 

 the composition of this acid. The proportions he assigns are 

 26-56 of carbon, 70*69 of oxygen, and 2*75 of hydrogen.* Now 

 carbonic acid is composed of 27-4 of carbon, and 72*6 of oxygen. 

 The proportion of carbon and oxygen, therefore, in oxalic acid 

 is precisely the same ; and the sole difference in composition 

 from carbonic acid is in the proportion of hydrogen it contains. 



The constitution of oxalic acid may likewise be inferred 

 indirectly from the method of Beizelius ; and it will be satisfac- 

 tory if a coincidence is thus obtained. The composition of the 

 real acid, as it is called, existing in oxalate of lead, is stated by 

 Berzelius at 33*22 of carbon, 66*53 of oxygen, and 0*25 of 

 hydrogen. But to this, to express the true composition of the 

 acid, are to be added the proportions of oxygen and hydrogen 

 expended in the formation of water, in the mutual action of the 

 acid and the oxide of lead. The quantity of hydrogen is 

 inferred from the quantity of oxygen : and there are different 

 principles connected with the doctrine, as has been already 

 illustrated in considering the action of sulphuric acid on a base, 

 whence the proportion of oxygen may be determined. Thus, it 

 must be a multiple of that existing in the composition of what 

 is called the real acid, or in the composition of the known defi- 

 nite compounds of carbon and oxygen, or it is equivalent to the 

 oxygen in the base, this quantity of oxygen being always 

 abstracted in the mutual action in combination with the requisite 

 proportion of hydrogen. Adopting this last principle as the 

 most direct, 100 parts of real oxalic acid, it appears from Berze- 

 lius's analysis, combine with 307*5 of oxide of lead : this quan- 

 tity of oxide contains 22*06 of oxygen, which is, therefore, to be 

 added to the composition of the acid, with the proportion of 

 hydrogen equivalent to this, 2*94. Hence this quantity of acid, 

 125 parts, is composed of carbon 33*22, oxygen 88*59, hydrogen 

 3*19 : or in 100 parts the acid consists of 26*5 of carbon, 71 of 

 oxygen, and 2*5 of hydrogen, proportions almost the same as 

 those assigned by Gay-Lussac, and affording a coincidence on a 

 difficult subject of experimental investigation that does honour 

 to the accuracy of these chemists. 



There can thus remain no doubt that the proportion of carbon 

 to oxygen in oxalic acid is the same as that dn carbonic acid. 

 The sole difference between them is in the proportion of hydro- 

 gen which the former contains : the one is the binary, the other 

 the corresponding ternary compound, similar to what exists in 

 other acids ; and hence also, in conformity to the analogy of 

 these acids, and to the principle which accounts for their acid- 

 ity, is explained the difference in their acid powers. 



The compound existing in a dry oxalate, such as oxalate of 

 lead, ought to contain no hydrogen ; for the whole of this ele- 



» Recberches Physico-Chimiques, torn. ii. p. 302. 



