Chap. 33.] Keyjer's Pills, Etbiop's Mineral,, &c. 2 1 1 



of a white calx. This preparation is chiefly ufed in 

 liniments externally. It is fometimes adulterated with 

 cerufe, as the red precipitate is with minium. The 

 fraud may be difcovered by expofing a fmall quantity 

 to heat in a fpoon j if pure they will be entirely dif- 

 fipated, but if they contain lead, or other impurities, 

 thefe matters will remain behind. 



If the fait formed by the combination of acetous 

 acid with the fixed vegetable alkali, commonly called 

 regenerated tartar, or kali acetatum, is added to the 

 folution of quickfilver in the nitrous acid, a double 

 exchange takes place j the alkali unites with the ni- 

 trous acid, while the acetous acid enters into combi- 

 nation with the mercury, and is precipitated. This 

 precipitate (being purified by folution in hot diftilled 

 water and filtration) has nearly the fame medical pro- 

 perties as calomel, and is Taid to form the bafis of 

 Keyfer's pills. The acetous acid does not aft on mer- 

 cury unlefs the latter is reduced to the ftate of a calx. 



As mercury is commonly, in . a ftate of nature, 

 combined with fulphur, fo it may be artificially united 

 to it with great eafe. When one part of this metallic 

 fluid is triturated with three parts of flowers of fulphur, 

 the mercury gradually lofes its metallic appearance, 

 and is converted, by its union with the fulphur, into a 

 black powder, called Ethiop's mineral. This com- 

 bination is more quickly effefted by mixing the mer- 

 cury with melted fulphur. When this compound is 

 expofed to a confiderable degree of heat it takes fire, 

 the greater part of the fulphur burns, and after the 

 combuflion a matter remains, which when pulverized, 

 is of a violet colour. To convert this powder into 

 cinnabar it is put into matrafles*, which are heated till 



* VefTels ufed in chemical operations, of glafs or earthenware, 

 generally of the fhape of an egg, and opea at the top, the necks- 

 are long or fhort, a? occ^fion may require. 



P 2 their 



