PRODUCTS OF ACETOUS FERMENTATION. 45 



The composition of acetic acid is C 2 H 4 O 2 aud its molecular 

 weight 60, because : 



C 2 = 24 



H<- 4 



O 2 = 32 



Makes . . 60 



Hence from 46 parts by weight of alcohol 60 parts by weight 

 of acetic acid may be formed, or by reducing the ratio to 100 

 parts of alcohol it follows that 100 parts by weight of alcohol 

 must yield 130.43478 parts by weight of acetic acid. (The 

 increase in weight has to be attributed to the absorption of one 

 atom of oxygen, atomic weight 16, against the loss of two atoms 

 of hydrogen, atomic weight 2.) Since these two atoms of hydro- 

 gen are themselves oxidized to water by the absorption of oxygen, 

 the total yield from 100 parts by weight of alcohol would be : 



Acetic acid 130.43478 parts by weight. 



Water 39.13043 " " " 



Total .... 169.56521 parts by weight. 



The quantity of oxygen required to form acetic acid and water 

 from 46 parts by weight of alcohol, amounts to 32 parts by 

 weight, hence for 100 to 69.562 parts by weight. The oxygen 

 is conducted to the alcohol in the form of air, and it can be 

 readily calculated how much of the latter is required to convert 

 a given quantity of alcohol, for instance 100 grammes, into acetic 

 acid. In round numbers the air contains in 100 parts by weight 

 23 parts by weight of oxygen. Since 1 liter of air of 68 F., 

 i. e., of that temperature which should at the least always prevail 

 in the vinegar generators, weighs 1.283 grammes, the oxygen con- 

 tained in it weighs 0.29509 grammes. Since, as above stated, 

 69.562 parts by weight are necessary for the conversion of 100 

 parts by weight of alcohol into acetic acid, it follows that 235.70 

 liters of air are required for the same purpose. 



Examinations as to the content of oxygen in the 'air escaping 

 from weir-conducted vinegar generators have shown that on an 

 average only one-quarter of the entire content of oxygen is con- 

 sumed in the formation of vinegar; hence four times the theorcti- 



