PRODUCTS OF ACETOUS FERMENTATION. 39 



has been most thoroughly studied, we find that besides alcohol 

 and carbonic acid large quantities of glycerin and succinic acid 

 and probably other bodies are formed from the sugar, which must 

 undoubtedly be classed among the products of vinous fermenta- 

 tion. Similar processes, no doubt, take place in the acetous fer- 

 mentation, and besides acetic acid and water other little known 

 products of fermentation are regularly formed. 



According to the nature of the sacchariferous fluids subjected 

 to vinous fermentation small quantities of certain bodies called 

 fusel oils are formed which are decidedly products of fermenta- 

 tion. They impart to the fermented fluid, as well as to the alcohol 

 distilled from it, such characteristic properties that from the odor 

 of the alcohol a correct judgment can be formed as to the material 

 employed in its preparation. 



In the conversion of such a fluid, or of alcohol prepared from 

 it, into vinegar, the fusel oils are also changed very likely oxi- 

 dized and with some experience the material (wine, beer, malt, 

 etc.), from which the vinegar has been made can be determined 

 by the sense of smell. The quantities of aromatic substances 

 which reach the vinegar in this manner are, of course, very small, 

 but they must nevertheless be classed among the most important 

 products of acetous fermentation, they being very characteristic 

 as regards the nature of the vinegar. Of the products of acetous 

 fermentation, besides acetic acid, aldehyde and acetal are best 

 known, these combinations appearing always, even if only in 

 small quantities, in the fabrication of vinegar according to the 

 methods customary at the present time. 



Acetic Aldehyde or Acetaldehyde. 



Acetic aldehyde, commonly called simply aldehyde (from alcohol 

 dehydrogenatum), is obtained by oxidizing spirits of wine by 

 means of manganese dioxide (pyrolusite) and sulphuric acid, 

 chromic acid, or platinum black, in the presence of air, or if alcohol 

 or ether is burning without a sufficient supply of air. It is also 

 formed by heating a mixture of acetate and formate of calcium. 

 It is contained in considerable quantities in the first runnings 

 obtained in the manufacture of spirit of wine. 



