164 Dr. Thomas Thomson [Sept. 



I stated in a former publication that bitartrate crystallizes 

 in right prisms with square bases. But I find, by a more 

 careful measurement, that the prisms are slightly obliq.ue, 

 and that the base also is slightly oblique. 



VI. RACEMATE OF STRONTIAN. 



This salt precipitates when solutions of chloride of 

 strontium and racemate of ammonia are mixed in atomic 

 proportions. 



It is a white, soft, tasteless powder, having very much 

 the appearance of magnesia alba. Its sp. gr. is 1*409. At 

 the temperature of 135° 100 parts of water dissolve 0'104 

 parts of this salt. 



When heated it gives oiF acetic acid, blackens, burns, 

 and leaves a white carbonate of strontian cohering together 

 in a friable mass . 



20 grs. of racemate of strontian, previously dried in a 

 gentle heat, were exposed to the temperature of 330°, till 

 they ceased to lose weight. The loss was 4*5 grs. No 

 higher temperature could be applied without incipient 

 decomposition taking place. I conclude, from this experi- 

 ment, that the constituents of the salt are 



1 atom racemic acid . 8*25 

 1 atom strontian . . 6*5 

 4 atoms water . . . 4*5 



19-25 



Tartrate of Strontian. 



When dilute solutions of nitrate of strontian and tartrate 

 of potash are mixed together, no immediate precipitate 

 appears, but the liquid gradually deposits beautiful crystals 

 of tartrate of strontian. They are right oblique prisms. 

 Mon M' 113° 20', Pon M or M' 90°. They are transparent, 

 have a vitreous lustre, and resemble the finest specimens of 

 calcareous spar. When the saline solutions are concen- 

 trated the tartrate of strontian precipitates in powder. 



This salt is tasteless. Its sp. gr. is 1*837. At the tem- 

 perature of 170° 100 water dissolve 0*67 of the salt. When 

 heated it gives out acetic acid, swells up like a cauliflower, 

 burns without flame, and, when acted on by the blowpipe, 

 leaves a very bulky friable carbonate of strontian. Its 

 constituents are 



