MINERALOGY. 



321 



Coal, the basis of the substances known by the term coalsj 

 is pure carbon ; from which circumstance they rank with 

 Minerals, otherwise from the v/ood-like appearance obser- 

 vable in every species of Coal, they seem to partake more of 

 a vegetable than a mineral nature. In all the varieties of coal^ 

 woodjin a greater or lesser degreebituminized is found, as also 

 seed-vessels and kernels of various kinds, the latter kinds are 

 principally found in countries where the land has been over- 

 flowed; the Coal used for domestic purposes, is known to 

 Mineralogists by the name of Slate or Black Coal, it is com- 

 posed of about sixty parts of Carbon, thirty to thirty-six of 

 Naptha and Asphalt, and from tv/o to eight of oxyde of lorn, 

 and earthy substances. It mostly occurs in horizontal strata, 

 and is very abundant in England, and some other parts of 

 Europe. 



Jet or Pitch Coal is a variety possessing a greater degree of 

 hardness than common coal, though very brittle ; it is found in 

 masses, as also io the forms of stems and branches of Trees ; 

 the coarser sorts are consumed for fuel, and the harder and 

 fine parts are made into beads and trinkets ; it is of a full 

 velvety black colour, burns with a greenish flame, much 

 odour, and its residuum is a yellowish ash, its weight is 

 about that of water. 



Arnber, this Mineral burns with a yellowish flame, much 

 odour and smoke, and leaves a black shining residuum ; this, 

 as well as what it yields after distillation, is used for the 

 bases of our finest black varnishes. Amber is found in beds, 

 likewise among sand, clay, and gravel, and is generally 

 esteemed of vegetable origin ; when distilled it yields the 

 Succinic Acid. 



