[ 6i ] 



26. Hepaticus. When fcraped or expofed to heat fmelljng 



like liver of fiilphur. 



27. Fluor. Intnfed in hot fulphurlc acid emits a gas 



which corrodes and diirolvesglafs. 



28. Apatites. W'hen fprink'cd on red hot charcoal emits a 



green phofphorefcent flame, not ealiiy 

 melted. 



29. BoRACiTES, Cubic, hard, lemitranfparent. 



ORDER IV. ARGILLACEOUS. 



30. Aluminaris. Dry and harfh, folublc almofl entirely in 



nitric acid. 



31. Argilla. Grcafy to the touch, plaflic, hardening by 



fire. 



32. Puteolana. Friable, hardening in the air when kneaded 



with water and qwicklime. 



33. C^MENTUM. Solid, hardening in the air when pounded 



and knead:;d with \yater and quicklime. 



34. ( ariosus. Rough, falling into pow-der in water. 



35. Ardesia. Fifllle, when moiilened giving out an argil- 



laceous odour. 



36. Basaltes. Opake, without luftre, compact, of a dull 



colour, eafily mouldering into pieces, melt- 

 ing intoablackilli glafs before the blowpipe. 



37. Lava. The produce ofvolcanos or fubterraneous fires. 



38. Mica. IScaly, fhining. 



39. Opalus. Of no determinate fhape when broken, corn- 



pail, melting with the greatclf difficulty. 

 4Q. Zeolithus. Eafily melting with ebullition, and in melt- 



ing emitting a phofphorefcent light. 



41. ScORLUs. Jyleltingjbut emitting no phofphorefcent light. 



ORDER V. SILICEOUS. 



42. Gemma. Cryflalline, hard and very hard, fhining in 



the dark. 



43. Olivinus. Eafily falling to pieces in the air, melting 



with great difficulty. 



44. Feldspatum. Lamellar, melting with foda into a tranfpa- 



rentglafs: mouldering in the air. 



45. Pyromachus. Not mouldering in the air, or melting without 



the greateft degree of heat, breaking into, 

 convex fragments. 



46. Petrcsilex. Melts "without ebulliiioji, cf fluvcry fradlure. 



