162 LACTIC ACID. 



oxygen, 6 equiv. hydrogen (372) ; in passing into 

 vinegar, it takes up 4 equivalents of oxygen, and 

 forms 1 equivalent of acetic acid. 



Carbon. Oxygen. Hydrogen. 



1 equiv. Alcohol, containing 4 2 6 



and 4 equiv. Oxygen "04 



forms — — — 



1 equiv. Acetic Acid ** 4 3 . 3 . 



and 3 equiv. Water "03 3 



377. When azotized matters are beginning to 

 decompose, they are at first not able to excite the 

 true alcoholic fermentation in solutions of sugar ; it 

 is necessary for this that their decomposition should 

 be tolerably active and advanced. But even in this 

 early stage they are able to effect a very important 

 change in the nature of sugar, and cause it to undergo 

 a peculiar acid fermentation, the result of which is 

 the formation of lactic acid. The relation of this 

 substance to sugar may be learnt from the fact that 

 it contains 6 equiv. carbon, 5 equiv. hydrogen, and 

 6 equiv. oxygen (445, 570). 



378. It sometimes happens also that, in place of 

 lactic acid, another acid substance, called the butyric, 

 is produced. This is especially the case when a 

 solution of sugar is left in contact with caseine, in 

 the first stage of decomposition. Butyric acid is 

 a colorless, sour, pungent-smelling liquid, readily 

 soluble in water and alcohol, and consisting of 8 

 equiv. carbon, 7 equiv. hydrogen, 3 equiv. oxygen. 



379. There are several other forms of fermentation 



