C 20 ] ftance refembling horn, for which reafon it is called horn-fiher, or lima cornua. experiment XXI. 54. If a faline fubftance forms fcatherlike cryftals, has a fiery, urinous tafte, melts in a moderate fire, and becomes volatile in an increafed heat, and when pounded and mixed with quick-lime will yield an urinous volatile fpirit, it is certainly SAL-AMMONIAC. EXPERIMENT XXII. 55. If a faline fubftance has at firft a fweetifh, but afterwards a cauftic bitter tafte, fwells and froths in the fire, but by length of time melts into a tranfparent glafs, if its folution ftrikes the fyrup of violets green, and by adding one of the acids to its folution, it will form by evapora tion and cryftallization firft a new neutral fait, called sedative salt, and laftly the remainder will form a neutral fait, compounded of the acid employed and the mineral fixed alkali, which is the bafis of this faline fubftance; if all this happens it muft be borax. 56. Borax precipitates all the metallic folutions, and alfo the folution of alum. It is brought in its crude ftate from Perfia, and the Eaft- Indies, and then called tincal; and may be refined into borax, by pouring hot water on the tincal, decanting the liquor and eva porating it gradually. EXPERIMENT XXIII. 57. If a faline fubftance has a ftyptic tafte, fwells and froths in the fire, or when put on a red- hot fhovel over the fire, crumbling after this operation