FERMENTATION. 87 



He filtered it, and precipitated it with acetic acid, 

 by which means he obtained one of the constituents 

 of ferment in the form of an albuminous substance, 

 which had not lost the power of coagulation. The 

 precipitate obtained by acetic acid from the alkaline 

 solution, and coagulated by boiling in water, rendered 

 the water limpid. He found that the substance, before 

 it was heated in water, was soluble in lime water, but 

 after it was so treated it was no longer so, Tartaric 

 acid dissolved this substance easily, and when saturated 

 with alkali the solution was sticky. The uncoagulated 

 ferment caused speedy and active fermentation in a 

 solution of sugar. 



The constituents of the ashes of ferment have been 

 analysed by Mitscherlich ; * but as the special 

 object of investigation was beer ferment, only the 

 principal points are of use to us. He found 7 '65 per 

 cent, ashes in the "upper ferment," 7'51 7'61 in 

 the "under ferment," obtained by burning upon 

 silver, supported on platinum, in a glass tube under a 

 stream of oxygen; and at the same time collecting the 

 volatile products, he gives 



Upper ferment. Under ferment. 



Phosphoric acid 41/8 39'5 



Potash 39.5 28'3 



Phosphate of Magnesia, 2 Mg O. Ph 05 16'8 22'6 



Phosphate of Lime, 2 Ca O. Ph 05 .. 2'3 9' 7 



The principal components found in the ashes of fer- 



* Erdmann's Journ. 1845, th. iii. s. 231. 



