1910.] 



The Alcoholic Ferment of Yeast-juice. 



325 



containing phosphorus equivalent to 0*2352 gramme Mg^PjO- in 25 c.c, was prepared. 

 The following mixtures were then made and incubated at 25° in pre.sence of toluene : — 



(1) 25 c.c. residue + 25 c.c. water. 



(2) 25 c.c. hexosephosphate + 25 c.c. water. 



(3) 25 c.c. residue + 25 c.c. hexosephosphate. 



After 5 hours' incubation the solutions were heateil for 5 minutes in boiling water, 

 made up to a known volume, and the phosphate and reducing power estimated in aliquot 

 portions of the filtrate. In order to ascertain tlie reducing power of the product, it was 

 necessary to remove the unaltered hexosephosphate, and this was effected by precipitation 

 with basic lead acetate, the estimation of the reducing power being made by means of 

 Pavy'a ammoniacal copper solution. In the following table the amounts of phosphate are 

 expressed as grammes of Mg.iPjO;, and the reducing power as grammes of glucose in the 

 quantities originally incubated. 



Solutions. 



Free phosphate as Mg.2P207. 



Eeducing substance as glucose. 



Before. 



After. 



Produced. 



Before. 



After. 



Produced. 



1 



2 

 3 



0 



0-0009 

 0 0009 



0 -0141 



0 -0030 

 0 -0968 



0 -0141 

 0-0021 

 0 -0959 



0 



0 -0244 

 0 -0244 



0 



0 -0275 

 0 -0595 



0 



0-0031 

 0 -0351 



The amount of reducing substance expressed as glucose produced by enzymic 

 hydrolysis is therefore 0'0351 — 0"0031 = 0"032, and that of phosphate is 

 O-0959-(0-O141 + 0-0021) = 0-0818 gramme. 



(6) Proof that the reducing substance is a sugar. 



Experiment 8. — 50 grammes of zymin (Schroder) were washed in the centrifuge four 

 times with water, in order to remove as much as possible of the coferment and thus to 

 diminish the fermenting power of the zymin, and the residue was made to 120 c.c. with 

 water. The following solutions were then incubated, Nos. 2 and 3 being added to ascertain 

 the amount of sugar formed by the spontaneous hydrolysis of the hexosephosphate and 

 from the carbohydrates of the zymin : — 



1. 50 c.c. washed zymin suspension + 55 c.c. of a solution of sodium hexosephosphate, 

 equal to 19-9 c.c. normal solution, and equivalent if completely fermented to 223 c.c. of 

 carbon dioxide at N.T.P. 



2. 50 c.c. washed zymin suspension + 55 c.c. water. 



3. 50 c.c. water + 55 c.c. sodium hexosephosphate solution. 



No. 1 gave a total evolution of 25-3 c.c. carbon dioxide under atmospheric conditions, 

 whilst Nos. 2 and 3 gave no gas. At the end of 48 hours all three solutions were removed, 

 filtered, and precipitated with lead acetate in neutral solution in order to remove all 

 phosphate and unchanged hexosephosphate. The excess of lead was then precipitated in 

 the filtrates with sulphuretted hydrogen, and the filtrates, after removal of the 

 sulphuretted hydrogen by a current of air, were neutralised and all made up to the same 

 volume. 



2 D 2 



