iQiSl 



/. Arthur Harris aiid Ross Aiken Gortner 



73 



TABLES 17-21 (continued) 



Data pertaining to concentration and mean molecular weights of solutes in 



the saps 



Table 20, Serie s D 



Table 21, Series E 



it, three laboratory Operations are involved: (a) the determination 

 of specific gravity by weighing in a pycnometer; {h) the determina- 

 tion of total soHds by drying a pipetted sample (10 c.c.) at 100°; 

 and (c) the measurement of the depression of the freezing point. 

 A slight error in any of these processes would influence the final 

 constant. Even in work with isolated chemical substances the de- 

 termination of exact molecular weights by cryoscopic methods pre- 

 sents difficulties. The close agreement in the observed mean mo- 

 lecular weights is, we believe, a good criterion of the care with 

 which our analyses have been carried out. 



