1910.] 



The Alcoholic Ferment of Yeast-jxiice. 



323 



further, that in these circumstances tlie addition of a small amount of 

 l)hosphate produces a relatively large increase in the fermenting power of the 

 enzyme. 



It was previously shown that the addition of phosphate to a mixture of 

 yeast-juice and a sugar not only caused the evolution of an equivalent 

 amount of carbon dioxide, but, in addition, produced an increase in the total 

 fermentation amounting to from 10 to 150 per cent, of the original. 



It now appears that when the total phosphorus present is largely reduced, 

 the increase produced by the addition of a small amount of phosphate may 

 amount to as much as 700 per cent, of the original, in addition to the quantity 

 equivalent to the phosphate, whilst the actual total evolved, including this 

 equivalent, may be as much as twenty times the original fermentation. This 

 result must be regarded as strong evidence in favour of tlie view that 

 phosphates are indispensable for alcoholic fermentation. 



The results indicated above were experimentally obtained in three different 

 ways. In the first place (Experiments 3 and 4) advantage was taken of the 

 fact that the residues obtained by filtering yeast-juice through a Martin, 

 gelatin filter are sometimes found to be almost free from mineral phosphates,, 

 whilst they still contain a small amount of coferment. The experiment therb 

 consists in comparing the fermentation produced by such a residue poor in 

 ])hosphate with tliat observed when a small amount of phosphate is added. 

 The second method (Experiment 5) consisted in carrying out two parallel 

 fermentations by means of a residue rendered inactive by filtration and a 

 solution of coferment free from phosphate and hexosephosphate (prepared by 

 a method shortly to be described) and adding a small amount of phosphate to/ 

 one of the solutions. 



The third method (Experiment 6) consisted in washing zymin with water 

 to remove soluble phosphates and then adding to it a solution of coferment 

 containing only a small amount of phosphate, and ascertaining the effect 

 upon the fermentation of the addition of a small known amount of phosphate. 



Experiment 3. — A slightly active filtration-residue was employed, 1 gramme of which 

 contained a total amo>mt of phosphorus corresponding with ()'038 gramme of MgjPjOj. 



or. 1 gramme residue + 2 grammes fructose + 20 c.c. water. 



b. The same mixture + 0'26 gramme crystallised sodium phosphate. 



Experiment 4. — A second slightly active residue was used, tlie total pliosphorus in 

 which was not estimated. 



a. 1 gramme residue + 2 grammes fructose + 20 c.c. water. 



b. The same mixture + 0"25 gramme crystallised sodium phosphate. 



Experiment 5. — In this case an inactive filtration-residue containing no free phosphate 

 and total phosphorus equivalent to 0'0342 gramme MgjPjO-, and a solution of coferment 

 VOL. LXXXII. — B. 2 D 



