C 99 ] 



100 parts of citric acid : 



Carbon - 33,811 



Hydrogene - , 6,33O 



Oxygene 59,859 



Ditto acetic acid : 



Carbon - - 50,224 



Hydrogene 5,62O 



Oxygene 44,147 



Ditto mucous or saclactic acid ; 



Carbon 33,69 



Hydrogene 3,62 



Oxygene 62,69 



These estimations agree nearly with the follow- 

 ing definite proportions. In oxalic acid 7 proportions 

 of carbon, 8 of hydrogene, and 15 oxygene;* in tar- 

 taric acid, 8 carbon, 28 hydrogene, 18 oxygene; in 

 citric acid, 3 carbon, 6 hydrogene, 4 oxygene ; in 

 acetic acid, 18 carbon, 22 hydrogene, 12 oxygene ; 

 in mucous acid, 6 carbon, 7 hydrogene, 8 oygene. 



The applications of the vegetable acids are well 

 known. The acetic and citric acids are extensively 

 used. The agreeable taste and wholesomeness of 

 various vegetable substances used as food, materially 

 depend upon the vegetable acid they contain. 



19. Fixed Alkali may be obtained in aqueous so- 

 lution from most plants by burning them, and treat- 

 ing the ashes with quick lime and water. The vege- 



* According to Dr. Thompson's experiments, oxalic acid consists of 3 pro- 

 portions of carbon, 4 of oxygene, and 4 of hydrogene, a result very different indeed 

 from that of the French chemists, 



