80 FEBMEISTTATION. 



by Colin and Thenard, ferment, in order effectually to 

 promote fermentation, must be acidified "by means of a 

 vegetable acid. 



Brendecke had observed that the addition at one 

 and the same time of acid, tartrate, or citrate of am- 

 monia, and of a porous body, such as charcoal, 

 straw, asbestos or goldleaf (?) to solution of grape 

 sugar causes active fermentation, and according to 

 him the salts remain unchanged. 



Schubert having multiplied these experiments, and 

 carried them out in detail, found that not only grape, 

 but cane sugar was decomposed in the same way. 

 The same effect may be produced by platinum black, 

 pumice stone, fresh precipitated alumina, paper, silver- 

 leaf, flower of brimstone, asbestos, and starch. The 

 operation is more tardy than in the case of ferment, 

 but it does not fail. 



The co-operation of a vegetable acid Schubert found 

 unnecessary, as the other substances named above can 

 act without it. Spongy platinum, pumice-stone, burnt 

 clay, oxide of iron, and pectin, caused fermentation 

 in the space of a few days. Nevertheless, acid 

 vegetable salts do very materially assist fermentation, 

 even when they are present in the shape of powder, 

 and cream of tartar is very useful, whilst other salts, 

 such as metallic and common salt, are prejudicial. 



According to Schubert, the formation of ferment 

 simultaneously with the commencement of fermenta- 

 tion, is by no means necessary to fermentation. Not- 





