372 ENZYMES 



Briefly put, he considers that the glucose, by the action of 

 catalase, is converted into lactic acid which is operated upon 

 by zymase, so that alcohol and carbon dioxide are pro- 

 duced. 



Other opinions have been put forward, but as the evidence 

 is not always sufficiently strong to stand the weight of the 

 theory, it is not proposed to consider them here. 



Zymase-like enzymes are not restricted to the yeasts ; such 

 bodies have been identified in other Fungi, such as Mucor 

 stolonifera* and Aspergilhis niger.\ 



IDENTIFICATION OF ETHYL ALCOHOL. 



The following tests may be employed for the identification 

 of ethyl alcohol in fermented liquors, etc. : — 



1. The presence of ethyl alcohol, except in very dilute 

 solutions, is usually betrayed by the smell. 



2. To the suspected solution add an equal volume of a 

 solution of iodine in potassium iodide, and then carefully add 

 just sufficient caustic potash to decolorize the iodine ; on 

 gently warming the solution, a smell of iodoform is produced 

 and a yellow crystalline precipitate is formed if alcohol be 

 present. If alcohol is present in abundance, it may keep the 

 iodoform in solution, and so prevent the formation of a pre- 

 cipitate ; this may be remedied by adding water. 



It is to be observed that this reaction is not given by 

 methyl alcohol, but is given by a number of other substances, 

 such as acetic aldehyde and acetone. Ethyl alcohol will, 

 however, not produce iodoform in the presence of ammonia, 

 whereas acetone will. 



3. Solutions of alcohol mixed with an equal volume of 

 concentrated sulphuric acid, and warmed with a few crystals 

 of sodium acetate, evolve a pleasant fruity odour of ethyl 

 acetate. 



4. Warmed with potassium dichromate solution and a little 

 dilute sulphuric acid, alcohol is oxidized to acetaldehyde, which 

 may be recognized by its smell. 



* Kostytschew : " Ber. deut. bot. Gesells.," 1904, 22, 207. 

 fMaximow: id., 1904, 22, 225. 



