Felfpar. 3*7 Accordingto Mr.Gerhard, itisnoway altered by a heat of 140°; but by fixed alkalisit is eafily fufible. According to Mr. Ehrman, it is by the heat of pure air converted into a femitranfparent glafs. But Mr. Gerhard teils us, he expofed his to- that heat for feven minutes without any effeft. Bv the analyfis of Mr. Klaproth it contains 0,965 filex, 0,025 argill, and 0,01 iron. By that of Mr. Gerhard, 0,92 filex, 0,03 ar gill, 0,02 calx, and o.oi iron. Baron Trebra found a flexible fandftone in Thuringia. , 3Sth Species. Felfpar. Of this foffil there feems to be three families; common felfpar, moonflor.c, and continuous fel fpar. ift Family. Common Felfpar, or Felfpar fimply fo called*. Spath fulible of Dsfmaretz, Spath Etinulam, Spathum Pyromachum. Its colour is moft commonly flefli red, fome- times bluifh grey, oftener yellowifh wlute, or * This name feems to nje derived from feh, a r°cT<; it being commonly found in granites, and not liom feld, a Seid; and henceI write it thus, fcllpar. nulk