142 



WORK OF M. R. SCHMIDT. 



The hydrochloric acid gas was then replaced by a stream of nitrogen dried over 

 phosphorus pentoxide, and the tube allowed to cool slowly. The cobalt chloride 

 gave a clear solution in water, which, however, when exposed to sunlight, deposited 

 a very small quantity of a flocculent brown precipitate. Not enough of this could 



be obtained for a complete examination. It did not contain 

 iron, and did not give the reactions of bivalent cobalt. It is 

 thought to be a cobaltic compound, produced by some oxidiz- 

 ing action brought about by the sunlight. Solutions kept in 

 the dark did not show this precipitate, even when allowed to 

 stand over night; but ten minutes' exposure to bright sunlight 

 was sufficient to cause the change. For this reason the con- 

 ductivities of cobalt chloride in aqueous solution are consid- 

 ered a little uncertain, and are probably a little too high. 

 Solutions in the alcohols and in glycerol were perfectly clear, 

 and remained so indefinitely, sunlight having no effect on 

 them. 



The conductivities of cobalt chloride are given in tables 

 107 and 108. The conductivities in pure glycerol increase 

 regularly, and are considerably higher than the corresponding 

 values for lithium bromide. This is just what would be ex- 

 pected if glycerol is a normal dissociating solvent. Cobalt 

 chloride would dissociate into three ions, while lithium bro- 

 mide would give only two, and the conductivities of the 

 former salt would accordingly be greater. 



The results are plotted as curves in figs. 63, 64, and 

 65. The curves are in every respect analogous to 

 those for lithium bromide, except in one minor point, 

 to be seen in fig. 64. Here the values of conductivity 

 of cobalt chloride in pure ethyl alcohol are abnormally 



low (at least for all ex- 

 cept the most dilute 

 solutions), consider- 

 ing that it is a ternary 

 electrolyte. Lithium 

 bromide, for instance, 

 in the tenth-normal 

 solution in ethyl alco- 

 hol, has a molecular 

 conductivity of 15.8 

 at 25, and we should 

 expect, other things 

 being equal, that cobalt chloride would give a value about 50 per cent greater than 

 this. The value of /x25 for cobalt chloride in ethyl alcohol is, however, only 4.71. 

 But knowing that many of the halides of the heavy metals tend to form complexes 

 when dissolved in organic solvents, it was suspected that these low results, at least in 



\> 

 '-+3 



c 



3 

 V 



c 



o 



O 



"5 



25 



75 



50 



Per cent. Glycerol 



Fig. 62. Conductivity of Lithium Bromide in Glycerol-Methyl 



Alcohol at 25. 



100 



