290 Dr. Murray on the Chemical Constitution of [Oct. 



from these illustrations must be inferred to exist in the combina- 

 tions of carbon and hydrogen. The two known proportions, 

 those existing in supercarburetted and carburetted hydrogen, 

 are 100 of carbon to 18 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 remainingjyegetable acids, the composition is evidently 

 less perfectly determined, partly from the difficulty of procuring 

 them insulated, andWrtry from the sources of error which attend 

 the experiment, and which have not been checked or detected 

 by the application of a just principle. It is, therefore, only from 

 repeated experimental investigation, aided by such an applica- 

 tion, that precision can be expected to be obtained. Still some 

 of these results afford very nigh approximations to the views 

 I have illustrated. 



The proportions I assign are those founded on the analyses by 

 Berzelius, corrected by the theory I have stated. He combined 

 the acid with oxide of lead, and submitted it to decomposition 

 in this state ; the water of composition he supposed to be thus 

 abstracted, and the real acid obtained. But the composition of 

 the acid is in fact subverted, and the water is formed from the 

 combination of its hydrogen with a portion of its oxygen. The 

 quantity of oxygen thus lost is discovered by the quantity of 

 oxide which the acid saturates, being equal, according to the 

 principle already explained, to the quantity of oxygen in the 

 oxide. The hydrogen lost is the quantity equivalent to this ; 

 and these quantities of oxygen and hydrogen being added to the 

 proportions assigned by Berzelius, give the real composition. It 

 is further necessary to remark, that as there has appeared reason 

 to infer the existence of four definite proportions of oxygen with 

 sulphur, observing the ratio of 1, 2, 3, 4, and four proportions 

 of hydrogen with carbon in the same ratio, so there will be found 

 equal reason to infer the existence of four similar proportions of 

 oxygen with carbon, 100 of carbon being combined in the first 

 with 62*5 of oxygen, in the second with 125 constituting car- 

 bonic oxide, in the third with 187-5, and in the fourth with 250 

 constituting carbonic acid. With these preliminary observations 

 it is sufficient to give the general results. 



Citric acid appears to be carbon with oxygen in the third 

 definite proportion, that between carbonic oxide and carbonic 

 acid ; and its hydrogen is nearly in the first proportion of that 

 element to carbon. 



Acetic acid is carbon with oxygen in the second proportion 

 nearly, and with hydrogen in exactly the second proportion, 

 that of 100 to 18. It is represented, therefore, by carbonic 

 oxide, with hydrogen in the proportion which constitutes super- 

 carburetted hydrogen. 



Gallic acid is carbon with oxygen in none of the four definite 



