IS 15.] Comlinalion of the Elements of Organic Nature. 95 



Article II. 



Experiments to determine the Definite Proporttofis m which the 

 Elements of Organic Nature are combined. By Jacob Berzclius 

 M. D. F. U.S. Professor of Chemistry at Stockholm. 



(Continued from p. 409, Vol. IV.) 

 III. Analysis of the Ternary Oxides. 



1. Analysis of citric acid. — I shall begin with citric acid, be- 

 cause its composition is the most simple of all the ternary oxides. 

 Ten parts of citrate of lead, strongly dried and decomposed by 

 sulphuric acid, produced 8-J»346" parts of sulphate of lead, equi- 

 valent to 6-582 of oxide of lead. Hence it follows that citrate of 

 lead is composed of 



Citric acid 34-18 100 



Oxide of lead 65'82 190 



100-00 



These lyO parts of oxide of lead contain 13-5F8 parts of oxygen. 

 In analyses made by combustion I found only 187 fi" 188 parts of 

 oxide of lead combined with 100 acid. Citrate of lead retains 

 humidity very strongly, and hence analysis makes the base always 

 too small. As this analysis was one of the first that I made, I had 

 not at that time found out the metiiod of drying the substances in 

 a sand-bath heated and exposed in a vacuum. 



I made a great many experiments on the citric acid, because 

 this acid and the tartaric served as a kind of exercise to prepare me 

 for these experiments. A part of tliem was unsuccessful, because 

 I had not at that time acquired the necessary practice in analysis. 

 One among the successful experiments gave as the result of the 

 analysis of 1 part of citrate of lead (which by combustion left for 

 residue ()4-95fi per cent, of oxide of lead, and in which there was 

 of course 35-014 percent, of acid,) 0-] Uf) water, and 0-503 of 

 carbonic acid in the state of gas; to tliis if we add 0-03 for the 

 carbonic acid retained by the soda, we obtain 0-533 of carbonic 

 acid. Tills shows us that citric acid contains per cent. : 



Hydrogen 3*800 



Carbon 41 -.{GD 



Oxygen , 54-831 



100-000 



We have seen that the capacity of saturation of this acid is 



I3-5H5; but 13-585 x 4 = 5'1-3'1. 'J'his shows us that citric 



acid ouglit to contain four times as mucli oxygen as the base by 



which it is neutralized. When we turn these numbers into 



