1915] 



MERRILL — ELECTROLYTIC DETERMINATION OF EXOSMOSIS 519 



and the specific conductivity, the corresponding values of the 

 latter for the values of x at 5, 10, 25, 50, 75, and 85 are given 

 herewith : 



Corresponding values in terms of spe- 

 Values of x on Wheatstone bridge for cific conductivity (to be multiplied 



resistance of 9,110 ohms. by 10 — 6 ) 



5 23 



10 49 



25 1.49 



50 4.48 



75 13.46 



85 25.43 



It is also advisable to have the conductivity values repre- 

 sented in terms of the concentration of some salt. The follow- 

 ing are the values of the specific conductivity of NaCl solu- 

 tions at 25° C. which had been determined by the writer for the 

 concentrations indicated : 



Concentration of NaCl Specific conductivity ( to be multiplied 



by 10~ 8 ) 



N/16 686.13 



N/32 353.94 



N/64 181.93 



N/128 93.25 



N/256 47.79 



N/512 24.54 



N/1024 12.60 



The correction for the specific conductivity of the water itself 

 is not considered in the above values. Neither is that cor- 

 rection applied in any of the work here reported, since it is 

 always a constant factor and only relative values are desired 



for the most part. 



Plants of Pisum sativum were used. For the method of 

 growing the seedlings, and other manipulations, see the writ- 

 er's paper referred to (Merrill, '15). The plants were grown 

 in full nutrient solution until a vigorous or well-developed con- 

 dition was attained and then they were transferred to redis- 

 tilled water 1 after rinsing the roots carefully and thoroughly 

 in once-distilled water. Ten plants were grown in each cul- 

 ture. The treatment was always given when the plants were 

 either in distilled water or in the solution, the effects of which 

 on the plants were being studied. In all cases where the read- 



1 Hereafter, throughout this paper, whenever "distilled water" is referred to 

 it will be understood to mean redistilled water with a specific conductivity of ap- 

 proximately 2 X 10 — a . If the ordinary distilled water is referred to, it will be 

 specially designated as "once-distilled water" or some such distinguishing term. 



