108 Studies on Solution. 



It should be mentioned that this work was carried on in a rather 

 small room with one window and one door at opposite ends of the 

 room, so that with care it was possible to keep the room temperature at 

 25 with less than 0.3 variation. Thus it was possible to measure 

 out the solutions in burettes and pipettes, provided that such were not 

 handled unnecessarily to cause heating and were always kept dry to 

 prevent cooling in evaporation. All burettes and pipettes were con- 

 nected with a tube filled with a mixture of calcium chloride and 

 soda lime to prevent contamination from moisture and carbon 

 dioxide. 



In handling the "run" the N/100 solution of one of the salts served 

 as a basis for the preparation of all the more dilute solutions. The 

 following scheme represents the method by which these solutions were 

 prepared : 



N /oo 



COc c 



After a number of experiments it was deemed inadvisable to wash 

 the measuring flasks with water; they were therefore rinsed with a 

 good grade of alcohol and then three times with conductivity alcohol. 

 The cells were filled with conductivity water until several hours before 

 use. They were then rinsed three times with good alcohol. Each 

 cell was finally washed three times with the solution of the particular 

 dilution to be "run" in that cell before filling. These cells, together 

 with one containing the conductivity alcohol, were then introduced 

 into the 15 bath, gently agitated twice within an hour's time to 

 insure absence of bubbles as well as to hasten diffusion, and then read. 

 They were placed successively in the 25 and 35 baths, allowing 

 for the same time and procedure as in the 15 bath. 



It will be remembered that the solutions were made up at 25 and 

 that the molecular conductances were measured at 15, 25, and 35. 

 Alcohol has such an appreciable temperature coefficient of expansion 

 that it was necessary to correct for the contraction and expansion at 

 the other temperatures. One liter of alcohol at 25 expands to 1.01114 

 liters at 35 and contracts to 0.98923 liter at 15. Therefore, to obtain 

 the molecular conductance at 35, one must multiply the specific con- 

 ductance at that temperature by the product of the molecular volume 

 and the factor 1 .01 1 14. Likewise, to obtain the molecular conductance 

 at 15, the specific conductance at that temperature must be multiplied 

 by the product of the molecular volume and the factor 0.98923. 



