374 



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



to set up fermentation. All the attempts hitherto made to effect this have 

 yielded entirely negative results, although both the kind of phosphate and the 

 amount added have been varied. 



Dipotassium hydrogen phosphate, a mixture of this with the dihydrogen 

 phosphate, disodium hydrogen phosphate, diammonium hydrogen phosphate, 

 micros mic salt, and a mixed phosphate of potassium and magnesium obtained 

 by boiling a solution of potassium dihydrogen phosphate with magnesium 

 carbonate, were employed, all of which are capable of producing the 

 characteristic effect of phosphates on the fermentation of glucose by yeast- 

 juice. 



Although these substances did not set up fermentation when added to an 

 inactive filtered residue and glucose, they did not affect the potential activity 

 of the residue. This is evident from the fact that the subsequent addition of 

 boiled juice produced an immediate fermentation. 



In every case the solution of the phosphate was saturated with carbon 

 dioxide at 26° and added to the solution of the inactive residue in glucose 

 solution also saturated with carbon dioxide at 26°, and in no case was any 

 evolution of gas observed after the cessation of the slight disturbance which 

 inevitably occurs when the solutions are mixed. The phosphate solutions 

 were all of 3/10 molar strength, with the exception of the mixed phosphate 

 of magnesium and potassium, 5 c.c. of which yielded 0-1594 gramme Mg 2 P20 7- 



In those cases in which the residue employed was slightly active, incubation 

 was continued until all fermentation had ceased before the phosphate solution 

 was added, and the amount of carbon dioxide evolved in this preliminary 

 period is given in the table. The amount of glucose, both in the solution of 

 rhe residue and in that of the phosphate, was throughout 10 grammes to 100. 





Amount of 

 residue. 



Preliminary 

 fermentation. 



Phosphate added. 



Carbon 

 dioxide 

 produced. 



Subsequent 

 evolution of 

 carbon dioxide 

 after the addition 

 of boiled juice. 



1 



25 c.c. 



41 -2 



2 



'5 c.c. KMg phosphate ... 







18 -4 



2 



25 „ 



47-7 



5 











3 



25 „ 



0-6 



3 



" KHP0 4 







268 -8 



4 



1 '6 gr. 



21 -5 



3 



„ KMg phosphate ... 







159 -2 



5 



1-2 „ 



10-7 



5 



si j) 









6 



0-5 „ 







2 



„ mixture of K,HP0 4 







3 c.c. per hour 











and KH-PO, 







7 



0-5 „ 







2 



„ (NH 4 ),,HP0 4 







4-2 „ „ 



8 



0-5 „ 







2 



„ (NH 4 )NaHP0 4 ... 







3-8 „ 



9 



0-5 „ 







2 



„ Na.,HP0 4 







3 -6 „ 



The foregoing conclusion is confirmed by the observation, made in the 



