200 STUDIES ON FERMENTATIOX. 



maize, and barley, which they then caused to ferment. One 

 day we had occasion to study the yeast produced in this estab- 

 lishment, and although we did not submit it to a sufficient 

 number of consecutive experiments to enable us to speak 

 positively, we are under the impression that the yeast produced 

 at Maisons-Alfort is a " high " one, differing from what may 

 be properly termed the " high " yeast of breweries in which 

 " high " fermentation is practised, but presenting a great 

 resemblance to the "high" yeast of which we have been 

 speaking. It would be interesting to confirm the opinion of 

 their possible identity by fresh studies, and the best way of 

 doing this would be to compare the qualities of beer which the 

 two yeasts could produce. 



Caseous Ferment. — We give the title caseous for a reason that 

 will presently appear, to a ferment which we came across also 

 accidentally. We were trying different methods of purifying 

 yeasts, and for this purpose had composed a liquid formed of : 



Ordinary wort . . . . . . . . . . 150 c.c* 



Water saturated with bi-tartrate of potash . . 50 c.c. 

 Alcohol of 90° 25 c.c. 



Quantities of this liquid were placed in several of our double- 

 necked flasks, submitted to boiling, then, after cooling, impreg- 

 nated with different ferments, and kept in a water-bath at 

 50° C. (122° F.) for one hour. 



In operating under these conditions with brewers' " high " 

 yeast, say, for instance, with what is called Dutch yeast, a kind 

 well known in distilleries, fermentation shows itself in the 

 course of a few days, in spite of the increased temperature to 

 which our liquid, which is hopped and slightly acid and 

 alcoholic, has been subjected. The time required for the 

 resumption of fermentation depends both upon the degree of 

 temperature to which the yeast has been exposed and upon the 

 duration of its exposure. These, however, are not the points 



* [28'4 c.c, = 1 fl. oz. approximately.] 



