OSMOTIC EQUILIBRIUM 



87 



To determine the osmotic pressures, the method of 

 thermo-electric cryoscopy was employed. The unaltered 

 yeast- juice was obtained by freezing the solid material in 

 liquid air and centrifuging the resulting liquid mass. 



The electrical conductivities of the juice, beer, and wort, 

 were also determined, to give an idea of the relative pro- 

 portions of electrolytes and non-electrolytes concerned in 

 the production of osmotic pressures. The apparatus was 

 the usual one, employed by the authors in previous work. 

 All specific conductivity measurements were carried out at 

 0, and are recorded as reciprocals of the resistance in 

 ohms, not in Siemens's units. 



Both pressed yeast and that skimmed from the vats 

 with adhering beer were employed in the investigation, 

 The beer was removed by centrifuging or by pressing 

 through a linen cloth by hand.* 



In Table XXIV. are recorded the results thus obtained, 

 A being the depression of freezing-point, P the osmotic 

 pressure in atmospheres calculated from A, and C the 

 specific electrical conductivity at 0. 



TABLE XXIV. 

 OSMOTIC PRESSURE or A YEAST AND WORT. 



* The brewers' yeast was obtained from Guinness's Brewery, Dublin, 

 through the kindness of Mr, A. McMullen, of the Research Laboratory. 



