CITRIC ACID TARTARIC ACID. 339 



Diluted pyroligneous acid is often sold for distilled vinegar ; 

 but distilled vinegar should have a fragrant odour, of which the 

 pyroligneous acid is destitute. 



Vinegar when taken in small quantities is beneficial, but in 

 larger proportion, taken habitually, is injurious. It produces 

 leanness, apparently by interfering with the healthy action of 

 the stomach. 



Citric Acid. The citric acid, as is well known, is a principal 

 constituent of the juice of the lemon, the orange (bitter and 

 sweet), the lime, the citron, the shaddock, and other fruits of 

 the genus Citrus, which, with little or no mixture of malic 

 acid, owe their sourness to the citric acid. It is contained also 

 in the cranberry ( Vaccinium oxycoccos), and in the fruit of the 

 dog-rose (Rosa canina). Along with an equal proportion of 

 malic acid, it exists in the gooseberry, the red currant, the 

 strawberry, raspberry, the cherry, and bilberry. Mixed with 

 tartaric and malic acids, it is found in the pulp of the tam- 

 arind. 



The formula of citric acid, as it exists in some citrates, is 

 C i2 H 5 ii . that of cr y S tallised citric acid, C 12 H'0 U + water ; 

 that of commercial crystals, C 12 H 5 O n + water 5 . 



The beneficial effects of lemon -juice in the cure and preven- 

 tion of scurvy in the human body are beyond dispute. But a 

 wide field is open for inquiry as to the utility of the other 

 fruits containing the same acid on the health of man and 

 animals. There is, moreover, reason to believe that the ap- 

 parent medicinal effects of citric acid in such diseases as rhu- 

 matic affections depend on its power of improving the general 

 health where a latent scurvy is present. 



Tartaric Acid. Tartaric acid exists free in tamarinds, 

 grapes, and the pine-apple. In mulberries it is present, com- 

 bined with potassa in the salt, well known as cream of tartar. 

 The same salt exists, besides the free acid, in tamarinds and 





