Qualitative Determinations. 
401 
samples of the chlorides of nickel and cadmium from Schu- 
charat were dehydrated in a similar manner. The C. P. sample 
of cobaltic chloride from Trommsdorff was treated in the 
manner just described; but the temperature was raised to about 
120° C. for several hours. The C. P. samples of lead nitrate 
and mercuric iodide from Merck, mercuric cyanide from Tromms¬ 
dorff, and zinc chloride from Kahlbaum were dehydrated, in the 
manner described above, at a temperature not exceeding 100° C. 
The silver cyanide was prepared from potassium cyanide and 
silver nitrate by Professor Kahlenberg, who dehydrated it and 
upon subsequent analysis found it to be pure. 
During the course of the qualitative experiments a great many 
interesting facts relative to the solubility, color of solutions, 
etc., were brought out, to most of which it will not be possible 
to call attention at the present time. It was soon observed that 
if ferric chloride did not yield solutions that conducted elec¬ 
tricity, it was not worth while to make tests with certain other 
salts; and for this reason many blank spaces occur in the fol¬ 
lowing table. In each case the conductivity of the solvent was 
tested and the deflection of the galvanometer needle noted. In 
nearly all cases it was found that the solvents were excellent 
insulators, giving no deflection of the needle whatever. In the 
case of acetic aldehyde, furfurol, and ethylene glycol, the de¬ 
flection was several divisions. When the salts were found to 
be quite soluble, the solutions were prepared in the resistance 
cell; but they were usually made up in small test tubes and 
frequently by the aid of heat. The strength of the solutions 
was not determined accurately; but it varied, being as high as 
five per cent, in some cases. 
The electrolytic dissociative power of a solvent is believed 
by the supporters of the dissociation theory to be measured by 
the conductivity of its solutions. Since the qualitative deter¬ 
minations throw some light upon the dissociative power of 
solvents, the results are given in Table I. In the first two 
columns are given the names and formulas of the solvent. In 
the next twenty-two columns is indicated whether the solutions 
of the several salts whose formulae head the respective columns 
conduct electricity. Where the solution conducted so poorly that 
