242 Ih\ Thomas Thomson on [Oct. 



burnt without flame, like tinder, and left 4*84 grs. of pro- 

 toxide of cobalt. This oxide was strongly ignited, without 

 any alteration in its weight. 



4-84 oxide of cobalt require for solution 9*395 of racemic 

 acid. Hence, the 14*76 grs. dried at 230° still retained 

 0*605 water, or very nearly half an atom. The salt dried in 

 the open air was composed of 



1 atom racemic acid . . . 8*25 

 1 atom protoxide of cobalt . 4*25 

 4 J atoms of water .... 5*0625 



17*5625 

 But when the oxide of cobalt thus obtained was digested 

 in water it gave out 0*25 gr. of carbonate of soda = 0*148 

 gr. of soda. If this soda, as is probable, existed in the salt 

 united to racemic acid, it would make 0*453 gr. of racemate 

 of soda. Deducting this, the original salt was obviously a 

 compound of 



1 atom racemic acid . . . 8*25 

 1 atom oxide of cobalt . . . 4*25 

 5 atoms water 5*625 



18*125 

 And the salt dried at 230° retained two-thirds of an atom of 

 water. 



XIV. — RACEMATE OF ZINC. 



This salt precipitates in powder when concentrated solu- 

 tions of racemate of soda and sulphate of zinc, in atomic 

 proportions, are mixed together. It is a soft white powder, 

 having a slight shade of buff. The taste of it is not strong, 

 but decidedly similar to that which characterizes the other 

 salts of zinc. Its sp. gr. is 1*980. At 60°, 100 water dis- 

 solve 1*067, and, at the boiling temperature, 2*58 of it. 

 When the boiling solution is cooled slowly, beautiful silky 

 crystals are deposited. They are minute, flat, four-sided 

 prisms, having some resemblance to sublimed benzoic acid. 



20 grs. of this salt, exposed for two hours to the tempera- 

 ture of 350°, lost 2*82 grs. of its weight. The heat being 

 raised and continued for two hours longer, the loss of weight 

 was 3*14 grs. In another trial 20 grs. lost 4*43 grs., and 

 became black when in contact with the glass. 



