96 On the Chemical Cunstitution of 



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 oi»-that 

 existing in the composition of what is called the real acid, or in 

 the composition of the known definite compounds of carbon and 

 oxvgen, or it is equivalent to the oxygen in the base, this quantity 

 of oxvgen being always alistracted in the mutual action in combi- 

 nation with the requisite proportion of hydrogen. Adopting this 

 last principle as the most direct, 106 parts of real oxalic acid, it 

 appears from Berzelius's analysis, combine with 3{)7'5 of oxide 

 of lead: this quantity 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, oxy- 

 gen 8S*59, hydrogen 3-19: or in 100 parts the acid consists of 

 26*5 of carbon, 71 of oxygen, and 2-5 of hydrogen, propor- 

 tions almost the same as those assigned by Gay-Lussac, and af- 

 fording a coincidence on a difficult subject of experimental in- 

 vestigation that does honour to the accuracy of these chemists'. 



There can thus remain no doubt, that the proportion of car- 

 bon to oxvgen in oxalic acid is the same as that in carbonic acid. 

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

 gen which the former contains ; the one is the binary, tl;e 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 acidity, is 

 explained the difference in their acid powers. 



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

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

 like the hydrogen of sulphuric acid, must, in the action of the 

 base, be combined with oxvgen, and abstracted in the state of 

 water. The small portion of hydrogen, therefore, stated by Ber- 

 zelius, must be considered as derived from error of experiment ; 

 and its presence would be admitted more readily from the idea of 

 some portion of hydrogen being essential to the constitution of 

 the acid, as necessary to form what was regarded as its compound 

 radical. In subsequent experiments, accordingly, Berzelius found 

 reason to infer that the proportion was smaller than he had at 

 first assigned. The minute quantity which he does suppose to 

 exist in real oxalic acid, (less than 1 percent.) he brings forward 

 as a difficulty in the atomic hypothesis. A fraction of an atom, 

 he remarked, cannot be supposed ; and therefore the small quan- 

 tity of hydrogen must be considered as an entire atom. But from 

 the proportions it must be held to be combined with 27 atoms 

 of carbon, and 18 atoms of oxvgen, that is, with 4o other atoms, 



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