TALC GENUS. gravity; from lithomarga, by its not pofleffing the fame fuite of colours, and its lets fpecific gravity; from bole, by its colours, want of Iuftre, and tranf- parency. 2. It is faid to be very foft in its repofitory, but when expoi'ed to the air becomes harder. ( 3* It is named Meerfchaum, from its great light' nefs, and its being fometimes found in the neigh bourhood of the fea, 4. The Tartarian name Keffikil which Mr Kirwan afiumes as the name of this fpecies, is faid to have been itnpofed on it by the Turks, becaufe the Tartars name it Kila. » 5. The fubftance of which the Indian tobacco- pipes are made is not known to mineralogifts. 6. Strabo and Pliny mention floating bricks, and lately Mr Fabroni has been able to form ftmilar ones* from a foflil fubftance, which is found near Caft^ del Piano near Sienna. Mr Brochant fufpe&s that it may be meerfchaum. FOUR' fti