166 Dr. Thomas Thomson [Sept. 



raised still higher the salt burns like tinder, becomes more 

 bulky, and assumes the appearance of a liquid boiling. At 

 last it burns with flame, and ultimately leaves a carbonate 

 of lime, slightly darkened by a mixture of charcoal. 



To determine the water chemically combined with this 

 salt, it was dried at 140° till it ceased to lose weight. 20 

 grs. of this portion were heated to 450°, and kept in that 

 temperature till the colour began to become brown. The 

 weight was reduced to 13*47 grs. This residue was heated 

 in a crucible till it was converted into carbonate of lime. 

 This carbonate weighed 7*5 grs., equivalent to 4*2 grs. of 

 lime. Now, 4*2 grs. of lime require for saturation 9*9 of 

 racemic acid. Hence, the salt was composed of 

 Racemic acid . . . 9*9 or 8*25 



Lime 4-2 „ 3-5 



Water 5*9 „ 4*91 



4*91 water is equivalent to 4^ atoms. I think it not unlikely 

 that the other frds of an atom were driven off by the first 

 heat of 140° ; and that racemate of lime dried in the open 

 air is a compound of 



1 atom racemic acid . . . 8 '25 



1 atom lime 3*5 



5 atoms water 5*625 



17*375 

 Had the temperature been raised to 150°, probably only 

 4 atoms of water would have remained. 



Tartrate of Lime. 



When this salt is obtained by double decomposition it 

 falls in the state of very minute crystals, which, instead of 

 cohering and forming hard lumps like the racemate of lime, 

 exist in the state of a loose powder, like sand. Hence, it 

 is easily washed, and dried on the filter. 



It is a white, tasteless powder, having asp. gr. of 1*9009. 

 100 parts of water at 58° dissolve 0*013 of this salt, while 

 100 parts of boiling water dissolve 0* 17 of it. When heated 

 nearly to redness, it burns like tinder, and leaves carbonate 

 of lime. 



Its composition seems exactly the same as that of race- 

 mate of lime. 20 grs. of it, previously dried in the same 

 temperature as the racemate had been, were exposed for an 

 hour to the heat of 310°. The loss of weight was 4*94 grs. 



