68 TETEEIN-ABT MATERIA MEDICA. 



Sulphur ProRcipitatum, a very fane, yellowish- 

 white, amorphous powder, odorless and almost taste- 

 less, insoluble in water or alcohol, is prepared by boil- 

 ing together sublimed sulphur 100 parts, slaked lime 

 50 parts, water 1,450 parts, which forms calcium 

 sulphide and hyposulphite. When the mixture has 

 cooled it is filtered; to the filtered liquid is added a 

 mixture of equal volumes of HCl and water until 

 almost neutral, when the sulphur is thrown down 

 as a fine precipitate, which after being thoroughly 

 washed is dried by gentle heat. 



Sodii Sulphis, transparent, colorless, monoclinic 

 prisms, efflorescent in dry air, odorless, having a 

 cooling, saline, and sulphurous taste and a neutral 

 or feeblj' alkaline reaction ; soluble in 4 parts cold 

 water, in 0. 9 part of boiling water, almost insoluble 

 in alcohol. It is prepared by passing sulphurous acid 

 gas through a solution of sodium carbonate, thus 

 precipitating crystals of acid sulphite of sodium; 

 this is further saturated with sodium carbonate and 

 rendered alkaline in reaction. 



Sodii Hyposulphis, large, transparent, colorless 

 monoclinic prisms or plates, efflorescent in dry air, 

 odorless, having a cooling, somewhat bitter and sul- 

 phurous taste, neutral or feebly alkaline reaction, in- 

 soluble in alcohol, soluble in 1.5 parts cold water, 

 partly decomposed by boiling water. Must be kept 

 in well-stoppered bottles. It is prepared by dissolv- 

 ing sulphur in a boiling solution of sodium sulphite 

 and crystallizing. 



Calx Sulphurata, a grayish-white powder, altered 



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