f *9 ] nitrous acid particles are extradied by pour ing a good quantity of hot watfcr bn it •, and by the, addition of a, folution of potatoes, or of a folution of fait of tartar, the nitre is obtained, after boiling or evaporating the mixed folutions. Native cryftalliied lalt- petre has hitherto been found but in one place. EXPERIMENT XIX. 51. If a faline folution forms cubic cryftais, when thrown on the fire or live coals decrepitates, or caufes a crackling noife; when brought in a velle! into the fire will melt after it had beeit red-hot, and congeal into a quite opaque mafs, it is MURIATIC or COMMON SALT. 52. The talle of common fait is fo well known to the civilized part of the human fpecies, that it is almoft unneceflary to give any other character, but refer the operator to the tafte. It is made of the brine of the fea, of that of fome wells and lakes, and often found folid in ftrata, but rarely mixed with earth or ftone; in which cafe it may be infuied with hot water, and the infufion decanted and evapo rated till it forms cryftais. EXPERIMENT XX. 53. Take fine filver, difiolve it in nitrou3 acid, by throwing in thin fmall particles at a time; in this folution of filver drop a few drops of a folution of fait, fufpebted to be common or muri atic? for in tliis cafe it will immediately become turhid, and form a precipitate, like curd ; which after bein^ feparated from the fupernatant li quor, dried and put into the fire in a glafs or earthen-ware veftel, will melt, and form a fub- C 2 fiance