Chap, 43-] [ *77 ] 



CHAP. XLIII. 



JET. AMBER, AMBERGRIS, AND MINERAL 

 TALLOW. 



General Properties of Jet. Its Nature and Origin. Amler.~Acid 

 cf Amber. Natural Hijlory of Amber.' Different Opinions of its 

 Origin. Ambergris^ Its Natural liijlory. -Mineral Tallow. 



JE T is a very compact bitumen, harder than af- 

 phaltum, always black, and fufceptible of a good 

 polilh. It is fo light as to fwim on water, becomes 

 electrical when rubbed, and is called black amber. 

 When burned it emits a bituminous fmell. Jet feems 

 nearly allied to coal, and particularly to that fpecies 

 which is called cannel coal 5 it is diftinguimed chiefly 

 by its ftructure, being compofed of fibres parallel to 

 each other like thofe of.wood. It feems in fact to be 

 wood, which has been long buried in the earth, and 

 penetrated by mineral fleam, fo as to affume the ap- 

 pearance and foiidity of coal. 



AMBER is the fubftance known to the ancients under 

 the name of electrum and fuccinum. In this fub- 

 ftance the property, which certain bodies have, of 

 attracting light fubftances, when rubbed, was fifft ob- 

 ferved, and was therefore called electricity. The moft 

 valuable amber is perfectly tranfparent, of a pale 

 yellow, and is much more efteemed when it happens 

 to contain any extraneous fubftance, fuch as leaves, 

 infects, &c. When broken it prefents a polifhed fur- 

 face at the place of the fracture. Amber does not 

 readily diffolve' in any fluid we. are yet acquainted 

 with. Spirit of wine has foms fmall effect upon 

 it, and from this combination a tincture is produced, 

 T bu| 



