110 KELLER AND MAAS — DIMETHYL RACEMIC ACID. [April 7, 



in different preparations of the salt indicate that it can crystallize 

 with either one-half mol. or one mol. of water. One specimen 

 yielded 3.76% and $-$57^ HoO (3.60% corresponding to >^ mol.), 

 while the analysis of another gave these results : 



Calnilated. Found. 



HjO 6.95% 6.87% 



Zn 25.18" 25.26 " 



Several attempts to estimate the zinc electrolytically gave lower 

 results, it being found impossible to effect a complete deposition of 

 the metal from a cyanide solution of the salt. 



Cobalt and nickel salts. A curious difference was repeatedly 

 noticed in the way in which these compounds separated from the 

 solutions in which they were formed. The cobalt salt is invari- 

 ably precipitated in the cold, and nearly quantitatively, from the 

 liquid, while the solution in which the nickel compound is formed 

 remains perfectly clear for days or weeks even, until it is heated or 

 evaporated ; a precipitate or residue is then formed which is about 

 as insoluble as the cobalt compound. Both salts deposit as crystal- 

 line crusts ; the color of the cobalt salt is a fine purple, that of the 

 nickel salt apple-green. Both contain one molecule of water of 

 crystallization, and their compositions correspond to the formulae 

 CeH.OeCo + H2O and CeH.OeNi -I- HoO. 



Calculated. Found. 



H^O 7.11% - 6.13% and 6.74% 



Co 23.72" 23.09 «* 23.34" 



HjO 7.07 " 6.73 " 6.85 " 



Ni 23.23" 23,19" 22.76" 



The metals were determined both as sulphates and electrolytically. 

 Cadmium salt. This is very similar to the zinc salt, but differs 

 from the latter in being anhydrous. Its weight remains constant 

 to above 160°. Its solution in potassium cyanide was electrolyzed 

 without any difficulty, and the electrolytic determination was 

 checked by one in which the cadmium was weighed as oxide. 



Required. Found. 



I. II. 



cd 38.61% 39.20% 38.78^^ 



Lead salt, CgH^OePb -\- lYiJd. In the earlier part of this inves- 

 tigation, considerable quantities of this compound were obtained as 



