98 On the Chemical Constiiulion of 



tion, that in caiburetted hydrogen* ; and hence, in conformity to 

 the law usually observed, hydrogen probably combines with carbon 

 in proportions following the ratio of 1,2, ij, 4 ; and taking a mean 

 which further investigation may determine with precision, 100 

 of carbon mav be supposed to combine vvith 9, IS, 27, and 36 of 

 hvdrogen. The proportion in oxalic acid will be conforn^.able to the 

 first of these relations, or half that in supercarburetted hvdrogen. 



Tartaric acid, which is next in strength to the oxalic, or is even 

 equal or superior to it in acidity, appears to be the same com- 

 bination with a larger proportion of hydrogen. 



Gay-Lussac employed tartrate of lime as the medium to de- 

 compose the acid. In this state, while the water of crystalliza- 

 tion of the acid is excluded, its composition is not subverted, for 

 there is in the formation of tartrate of lime no abstraction of what 

 is called comljined water. The results therefore give tlie real 

 constitution of the acid. The proportions he assigned are carbon 

 24"05, oxygen 69*3, hydrogen 6-62. Berzelius operated on tar- 

 trate of lead. The proportions he assigns are carbon 35'9S, oxy- 

 gen 60-21, hydrogen 3-807. Hut in the formation of tartrate of 

 lead by the action of the oxide on the acid, a large quantity of 

 water is formed. This being taken into calculation, his results 

 agree perfectly with those of Gay-Lussac. 



The proportion of the carbon to the oxygen, it is evident, is 

 not much different from that which constitutes carbonic acid ; 

 and the deviation is not greater than may fairly come within the 

 allowance due to errors liable to he present in a sui)ject of analy- 

 sis so difficult. 



The proportion of hydrogen is much larger than that in oxalic 

 acid : it must, however, in conformity to the law which has been 

 stated as regulating the proportions in ternary acids, bear a cer- 

 tain relation to the radical of the acid, that is to the carbon. 

 And it is interesliixg to discover that this larger quantity is pre- 

 cisely the other definite proportion which it has appeared from 

 these illustrations must be inferred to exist in the combinations of 

 carbon and hydrogen. The two known proportions, those ex- 

 isting in supercarburetted and carburetted hydrogen, are 100 of 

 carbon to IS of hydrogen, and 100 to 36 ; the other two are those 

 of 9 and 27. The first was found in oxalic acid, and the other is 

 discovered in tartaric acid, the proportion in the above analysis 

 of 24-05 to 6-62, being that of 100 to 26-5. 



In the remaining vegetable acids the composition is evidently 

 less perfectly determined, partly from the difficulty of procuring 



* The composition of eitlier of the carburetted hydro;^en gases is not so 

 well determined, as to exclude a correction sufficient to establish a perfect 

 coincidence. 



them 



