ON FERMENTATION. ^55 



water. Accordingly I took some cow's milk, gooseterry 

 juice, and a solution of gelatine, and exposed them to the 

 boiling heat of water saturated with salt, at first daily, af- 

 terward every other day. 



Two months after all these substances were perfectly 

 good. The butter, that had collected on the surface of the 

 milk, was very sweet, only it was a little harder than fresh 

 batter ; and the milk appeared a httle thinner than before 

 the experiment. I need not say, that some milk, goose- 

 bei-ry juice, and jelly, which I kept by way of comparison, 

 «oon altered. 



Urine, which is known soon to putrefy, and from acid, Uiine keej» 

 • . . 11 »• Ml 1 1 loif ifairbe 



Whjch It is at first, to become alkaline, will keep a long excluded. 



time in vessels closely stopped, when it has scarcely been in 

 contact with the air: it retains its transparency, acidity, 

 and smell ; and no amraoniaco-magnesian phosphate is de- 

 posited, though Sometimes uric acid separates. When 

 urine is left in contact with a small portion of air, it absorbs 

 its oxigen pretty readily, and then the decomposition stops: 

 but if a sufficient quantity of air be present, a great deal of 

 carbonate of ammonia is formed, and ammoniaco-magnesiatt 

 phosphate is almost always deposited wjth the phosphate of 

 lime. The decomposition of urine therefore, as we see, is 

 ' not analogous to fermentation ; since the latter, when once, 

 it has begun, goes on without the assistance of oxigen 



gas- 

 Returning to fermentation, and considering, that sugar Essential 6iU 



and the veast of beer will ferment without the contact of ^^'"'^'^'^ ''^ ^*^ 



. , p , , . meuts, 



air, while the must ot grapes has not this property ; we are 



forced to admit, that there is an essential difference between 



"yeast of beer and the ferment of the grape. Yeast is solid, and 



nearly insoluble in water : ferment, on the contrary, in the 



'state in which it is found in fermentable fruits, is liquid ; 



or, if it be solid, it must be very soluble in their juices. It 



appears to me however, that it may be solid in a great 



ni mber of substances, but in a peculiar state, and different 



' from that of beer yeast. Still it is very possible, that there but, perhap« 



is but one ferment, and that its difference from the yeast of °^"^'y ^™™ 

 1 -111 >'i 1 • T t • • • oxigenaiiwn. 



beer is to be ascribed only to a little oxigen. In tins view it 



would be analogous to indigo, which is capable of oxidation 



Sind disoxidation. Fer* 



