250 Dr. Thomas Thomson on [Oct. 



but by half an hour's exposure to a heat of 290° it was 

 reduced to 97*1 grs. It blackened at a low heat, when 

 heated in contact with water. 



The residual liquid being evaporated to dryness and 

 heated on the sand bath, became black at the bottom, and 

 weighed 63*6 grs. 



It is obvious that the whole racemate of silver did not 

 precipitate when the saline solutions were mixed. For the 

 whole of the salt, supposing it was in an anhydrous state, 

 would have amounted to 115 grs. Thus, there were 17*9 

 wanting. Had the residual salt contained only nitrate of 

 soda, its weight would have amounted only to 53*75 grs. 

 instead of 63-6 grs. and it would not have blackened while 

 drying. This blackening indicates the pressure both of 

 racemic acid and oxide of silver. 



To form an estimate of the constitution of the racemate 

 of silver, 20 grs. of it were heated over the lamp in a plati- 

 num capsule. It fused, blackened, smoked strongly, and 

 finally left 11*7 grs. of metallic silver. Now, 11*7 metallic 

 silver are equivalent to 12*55 grs. of oxide of silver. And 

 this quantity of oxide requires for saturation 7*01 grs. of 

 racemic acid; making, together, 1956 grs. If we admit 

 the 0*44 gr. wanting to make out the 20* to be water, the 

 constituents of the salt will be 



Racemic acid . . . 7*01 

 Oxide of silver . . . 12*55 

 Water 0*44 



20*00 

 This is equivalent to 



1 atom racemic acid . . 8*25 



1 atom oxide of silver . . . 14*75 

 J atom water 0*5625 



23*5625 

 The water actually present amounted only to 0*517. It 

 is doubtful whether this small quantity was chemically 

 combined, or only mechanically lodged in the salt. 



XX. RACEMATE OF BISMUTH. 



I attempted to form this salt by mixing together solutions 



