24 



Conductivities and Viscosities in Pure and in Mixed Solvents. 



The solvent was kept in half-liter glass-stoppered Erlenmeyer flasks, 

 and the solutions when made up were preserved in 35 c.c. flasks of 

 similar design, which were sealed with rubber cement. 



On account of the high price of the solvent, only 25 c.c. of each 

 solution was prepared, this amount serving both for conductivity and 

 viscosity measurements. All operations in preparing the solutions were 

 carried out at 20. 



APPARATUS. 



Conductivity apparatus. The conductivity apparatus was identical 

 with that employed in our earlier work on binary and ternary mixtures 

 of water, acetone, and glycerol; the method of obtaining duplicate 

 readings and other details being exactly the same as in the earlier work, 

 excepting the use of a rocking commutator with mercury contacts 

 instead of the two-blade, double-throw switch used in reading both 

 ends of the bridge, the object being to eliminate as nearly as possible 

 all external resistance. The conductivity cells were of the type recently 

 employed in this laboratory for work with non-aqueous solvents, and 

 were carefully calibrated at regular intervals. 



Viscosity apparatus. This was essentially the same as in our earlier 

 investigations. We have designed and used an improved support for 

 the viscosi meters, which is particularly well adapted to our new thermo- 

 stat. A new pyknometer has also been devised, which has proved to 

 have advantages over the older form. (See Chapter I.) 



Thermostats. The new form of constant-temperature bath for con- 

 ductivity and viscosity investigations has already been fully described 

 in Chapter VI of Publication No. 210 of the Carnegie Institution of 

 Washington. 



DISCUSSION OF RESULTS. 



Tables 8 to 27, inclusive, give the molecular conductivity, dissocia- 

 tion, viscosity, and fluidity, as well as the temperature coefficients 

 both of conductivity and fluidity, for all of the salts studied. Measure- 

 ments were made at 15, 25, and 35. 



TABLE 7. Comparison of the Various Solvents. 



