* Salts. 197 



times it flioots on the furface of damp walls, 

 and is then called falpetere de houffage. Mon. 

 Mineral^ 446, but Mr. Lavot/ier has fhewn that 

 old mortar often contains only nitrous felenite, 

 which is converted into true nitre by mixture 

 with aihes, though thofe afhes contain a large 

 proportion of tartar vitriolate and glauber's 

 fait, becaufe theie falts decompofe the calca- 

 reous felenite, and form nitre by the way of 

 double decompofition, Mem. Par. 1777. 



SPECIES XVI. 

 Cubic Nitre. 



This fait requires but 3 times its weight of 

 water to diffolve it, at the temperature of 60 ; 

 its fpecific gravity is about 1,87; vegetable 

 fixed alkali decompofes it without forming a 

 vifible precipitate in its folution, neither does 

 the tartarous acid precipitate any thing from 

 it ; with vitriolic acid (the nitrous being ex- 

 pelled) it forms glauber's fait; it deflagrates 

 like prifmatic nitre, and alfo forms aqua regia> 

 in the fame circumftances. 



100 Parts of cubic nitre contain about 29 

 of real acid, 50 of mineral alkali, and 21 of 

 water. 



According to Mr. Bowles, it is found 

 native in Spain. 



O 3 SPECIES XVII. 



