34 ON PREPARING PURE BARYTES. 



a great deal more becomes carbonated by dissolving it afresh 



in boiling water. It is obvious, that all these deductions 



XT . ,. taken together will amount to a considerable sum, while in 

 None m trie ° 



other.] the decomposition of the nitrate we obtain the whole of the 



quantity it contained, which amounts to nearly half the 

 weight of the dry salt; and that besides this process is neither 

 difficult nor expensive, to those who know how to conduct it 

 properly. The following are the precautions to be taken, to 

 ensure its success. 



Process for de- Let a covered crucible be nearly two thirds filled with dry 



composing the and powdered nitrate of barytes, and placed in a common 

 furnace, heated moderately so as to cause the salt to dis-i- 

 solve in its own water of crystallization. Increase the fire 

 gradually, and with caution, on account of the considerable 

 tumefaction that takes place toward the end. When the 

 mass, which ought then to be of a cherry red, no longer emits 

 any bubbles, cover the crucible with charcoal to the depth of 

 an inch or two ; fit on the furnace its dome, furnished with a 

 plate iron chimney; let it heat thus for a quarter of an 

 hour; and afterward withdraw the crucible from the fire, 

 break it, and put the barytes into a close vessel as quickly 

 as possible. 



71bs. produced In this way I lately treated seven pounds of nitrate, which 



Slbs 602. of j divided into three common crucibles, and placed in the 

 pure barytes. r 



same furnace. The charcoal expended cost about 30s. 



[Is. 3d.]; the decomposition was completely effected in 



two hours; and I obtained 3lbs. 6oz. of perfectly pure ba« 



Necessary cau- rytes. But it is to be observed, that, if the barytes be kept 



tion. too long in the fire after the nitrate is decomposed, it will 



become considerably carbonated : and if the quantity be at 



all too great, it is impossible, whatever heat we afterward em* 



ploy, to deprive it completely of carbonic acid. This is the 



whole of the difficulty, which is completely removed, by 



acting as I have directed. 



F Thus I conceive it is in reiditv more economical, to ex- 

 Advantages of t 



thia mode. tract the barytes from the nitrate by the help of fire, than to 

 follow the process proposed by Mr. d'Arcet: for even sup- 

 posing the barytes to be equal in quantity by both processes, 

 which I have shown cannot be the case, the price of the 

 potash I must have employed would have nearly doubled 



the 



