196 Elements of Mineralogy. 



SPEC IBS XIV. 



Vitriols of Silver, Mercury and Lead. 



Thefe I fhall treat of among the ores of 

 thofe metals. 



SPECIES XV. 

 Nitre 9 or Prifmatic Nitre. 



Nitre requires about 7 times its weight of 

 water to diflblve it in the temperature of 60: 

 its fpecific gravity is 1,92, vegetable alkalis 

 do not render its folution turbid, but the acid 

 of tartar does ; it deflagrates with burning 

 coals, or on a red hot iron, and mixed with 

 marine acid it makes aqua regia. 



100 Parts of nitre contain about 30 acid, 

 63 vegetable alkali, and 7 of water. 



It is faid to be found formed by nature in 

 certain clays in the Eaft Indies^ China, 

 Spain,* and in Siberia, in the cavities of rocks,f 

 alfo on the furface of mafles of chalk, in the 

 neighbourhood of Rocheguyon, and in fome 

 wells in great towns, as London and Berlin ; 

 but more frequently in old mortar, fome- 



* i Watfon, 315, Bowls, Spain, 70, 78, Suenlk. Handl. 

 1772. 2 Quart, f Phil, tranf. 1763, p. 209. J Macq. 

 Dift. Nitre. i Wats. 293. 



times 



