JACQUES LOEB 



87 



The curve "after 1 houjjoVis clear, since it is chiefly the expression 

 of the variation of the degree of sweUing of the casein particles since 

 not as much has goi>e into solution as after 22 hours. We notice that 

 the volume occupi^^ci by the solid particles in the 1 hour curve is a 

 minimum at the "ir.^jlectric point, that it rises steeply af ter pH 3.1, 

 and it drops at 2.2, and that a second drop commences at pH 1.8. 

 The two drops have a different cause. The drop at pH 1.8 is due 

 to a diminution of the degree of swelling of the sediment, while 

 the drop at 2.2 in the 1 hour curve is due to the fact that at 2.2 the 

 solubility of casein chloride is a maximum. This conclusion is sup- 



pH 1.4 1.6 1.8 20 2.2 24 2.6 2.8 3.0 3.2 3.4 3.6 3.8 40 4.2 



Fig. 8. Dry weight of sediment of casein chloride solutions after 1 and after 22 

 hours. 



ported by the fact that the drop at 2.2 increases in time and is very 

 considerable after 22 hours (Fig. 7), while otherwise the 1 hour and 

 the 22 hour curves show only minor differences. 



The proof that this interpretation in the volume curves of Fig. 

 7 is correct is furnished by Fig. 8 where the ordinates are the dry 

 weights of the sediments, the volumes of which are given in Fig. 7. 

 1 gm. of powdered casein had when dried for 24 hours at between 

 90 and 100° a dry weight of 0.87 gm. 



That part of the casein chloride which goes into the supernatant 

 liquid {i.e., which is not contained in the sediment) consists of two 



