530 Mr. W. J. Young. Hexosephosphate formed by [July 30 r 



a small sample by measuring the rate of evolution of carbon dioxide under 

 similar conditions. When the rate of fermentation had fallen, more 

 phosphate was added, and the additions continued so long as this acceleration- 

 could be produced. The mixture was then boiled, and filtered from the 

 coagulate formed. 



In a typical experiment, a mixture of 440 c.c. of yeast-juice and 

 55 grammes of glucose was employed, and 440 c.c. of the potassium 

 phosphate solution (37 grammes, K2HPO4) were added 80 c.c. at a time.. 

 When fructose is used in place of glucose, much more phosphate may be 

 added ; thus in one case a mixture of 495 c.c. of yeast-juice and 200 grammes 

 of fructose was employed, and 1000 c.c, of the phosphate solution 

 (104 - 4 grammes K 2 HP0 4 ) were added, 100 c.c. at a time. 



The liquid, after boiling and filtering, was always found to contain a little 

 free phosphate, and this was removed by adding a solution of magnesium 

 nitrate, making alkaline with potash, stirring well, and allowing to stand for 

 a few hours. The filtered liquid was then neutralised with acetic acid, lead 

 hexosephosphate precipitated by the addition of lead acetate, and washed 

 repeatedly with water by means of a centrifugal machine, until the washing? 

 no longer reduced Fehling's solution. It was found that this precipitate 

 invariably contained traces of some nitrogenous material, and it was there- 

 fore suspended in water, decomposed with sulphuretted hydrogen, and the 

 excess of this gas removed after filtering by passing a current of air through 

 the solution. The liquid was then neutralised with potash and the lead salt 

 reprecipitated with lead acetate, the process being repeated until the preci- 

 pitate, after washing, was free from nitrogen. Usually two or three such 

 precipitations were found sufficient. The salt was then filtered off and dried,, 

 first on a porous plate and then in a vacuum over sulphuric acid. It was 

 thus obtained as a white, amorphous powder, free from nitrogen, which, on 

 decomposing with sulphuretted hydrogen, yielded an acid solution containing 

 no free phosphate precipitable by magnesium citrate mixture. 



The preparation of yeast sold under the name of " zymin," which is 

 obtained by treating pressed brewers' yeast with acetone, may be used in 

 place of yeast-juice for the preparation of hexosephosphate. In one 

 experiment 10 grammes of zymin, 10 grammes of glucose, and 100 c.c. of 

 water were incubated at 25°, and 75 c.c. of a 0-3 molar solution of potassium 

 phosphate added, 15 c.c. at a time. After rapid fermentation had ceased the- 

 mixture was filtered without boiling, and the lead compound obtained from 

 the filtrate as before. 



Lead compounds have been prepared from glucose, fructose, and mannose, 

 and the analyses of several different preparations of these compounds are- 



