296 



Mr. S. G. Paine. 



[July 12, 



Effect of Auto-fermentation. 

 A small loss of carbon dioxide, accompanied by production of alcohol, 

 does always take place, and the results are subject to error arising from 

 this cause. It was found by direct experiment that, under the conditions 

 employed, a maximum loss of about 09 grm. of solid was caused by 

 auto-fermentation. 



A loss of 1 grm. in total solids during an experiment has been found 

 to produce a positive error of 5 per cent, on the calculated weight of 

 liquid outside the yeast-cells, so that the results to be given later must be 

 considered to be liable to an error of this order. To eliminate this 

 factor as far as possible, the mixture was allowed to stand in the cold 

 room at a temperature ranging from — 2 to + 1°. 



Calculation of the Formula for Obtaining the Weight of Liquid outside the 

 Yeast-cells. 



Let I = weight of initial liquid, y = weight of initial yeast, then the total 

 weight W = I + y ; and if g = percentage of solids in I, and e = percentage 



of solids in y, then the total solid matter present V = r Ii^ + r ^^. 



Both these values W and V are assumed to remain constant during the 

 experiment. 



Further, let L = weight of final liquid, Y = weight of final yeast, then 

 Y = W — L ; and if G = percentage of solids in L,and E = percentage of solids 



in Y, then the total solid matter V = j^-j-J^. Substituting for Y in terms 



of W and L, 



LG (W-L)E _ Y 

 100 100 



whence L = EW — 100 V ^ y . g ^g^g^ difference from W. 

 E — G 



Having thus calculated the weights of liquid and yeast at the end of 

 the experiment, the distribution of the substance under investigation, 

 before and after treatment, is found from the analyses of the initial and 

 final liquid and the initial and final yeast ; at the same time, any inter- 

 change of other solid matter and of water is made manifest. 



Alcohol. 



Table V shows the results of experiments with alcohol of various con- 

 centrations. This substance was chosen as it might be expected to diffuse 

 freely through the envelope of the cell. Assuming the whole of the water 



