370 Dr. A. Harden and Mr. W. J. Young. [June 14, 



residue in the solid form, in which condition it retains its properties for a 

 considerable time. 



This is accomplished by spreading the sticky mass left on the filter over 

 a large watch-glass, and exposing it over sulphuric acid in a vacuum. 

 The residue dries up in a few hours to a brittle mass, which is converted 

 by grinding into a light yellow powder. 



Complete removal of the coferment is generally not effected by a single 

 filtration, and the powder prepared as above is usually found to be slightly 

 active. A completely inactive residue may, however, be obtained by 

 redissolving in water and repeating the nitration and desiccation. The 

 powder prepared in this way and dried over sulphuric acid in a vacuum 

 for 15 hours only loses its potential activity slowly. The following examples 

 show the original inactivity of the powder, its fermentative power in 

 presence of boiled yeast-juice, and the loss of this power with lapse of 

 time : — 



I. 200 c.c. of yeast-juice were filtered in quantities of 50 c.c. through 

 Martin filters and yielded 17'6 grammes of dry solid. This was dissolved 

 in 50 c.c. of water and again filtered, yielding 9"2 grammes of dry solid 

 residue. 



The following experiments were then made at 26° in presence of toluene : — 



1. March 8, 1906. One gramme of dry residue was dissolved in 15 c.c. 

 of water and 1*5 grammes glucose added. No evolution of carbon dioxide 

 was observed ; 12 c.c. of boiled yeast-juice containing 1*2 grammes of 

 glucose were then added. Fermentation at once commenced, and 108 c.c. 

 of carbon dioxide were evolved in 20 hours, when the experiment was 

 discontinued. 



2. Two months later (May 18, 1906) a similar experiment was carried 

 out, a sample of the same boiled yeast-juice being employed. As before, 

 1 gramme of the residue dissolved in sugar solution was quite inactive. 

 On the addition of the boiled juice fermentation at once commenced ; the 

 rate was, however, only about one-third of that attained in the previous 

 experiment, and fermentation ceased when only 42 c.c. of carbon dioxide had 

 been evolved. 



Although the fermentation in the first experiment was not continued to 

 the end, the comparison shows clearly that the potential activity of the dry 

 residue had greatly diminished. 



II. In the case of another sample of dry residue, with which two similar 

 experiments were made with the interval of a week, it was found that in 

 the first experiment 364 c.c. of carbon dioxide were produced, and in the 

 second 344 c.c, a difference of only about 5*5 per cent. 



