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small trinkets. We shall consider true Jet to have passed 

 from the remains of some sort of wood, as the ligneous 

 fibre is in some instances seen ; in other specimens it 

 is so condensed and compact as not to be discernible. 

 This substance appears also to be saturated, as it were, 

 with bitumen, insomuch that it readily inflames, losing 

 about 14 grains in 20, with much smoke, and a slight 

 bituminous odour. The remaining cinder, if continued 

 to burn, leaves a very trifling residuum. It is well 

 known to be of the most opaque black (witness the 

 common saying, " black as jet*"); but it will bear a 

 fine polish. Its surface excited by friction possesses the 

 resinous electricity, which distinguishes it from cannel coal, 

 a substance it very much resembles. It may be scratched 

 by common calcareous spar, and will itself scratch amber 

 and gypsum. The fracture is conchoidal, occasionally re- 

 taining that of wood. Lustre 3 to 4 ; transparency 0. Spec. 

 Grav. 1-104 to 1*744. Kirw. It has generally been said to 

 swim on water. Thin pieces, indeed, laid lightly on the 

 water, will float for a short space of time; but at length 

 the water passes over them, and they sink : perhaps some 

 slight trial of this kind might cause the common idea of its 

 swimming. Of many pieces in our possession none will 

 swim. Linnaeus called it Bitumen Gagas, from the river 

 Gages in Lycia, near which it was found. The presence of 



* The streak or powder is always brown. 



