HETINASPUALT. 1 1 1 



RETINASPHALT. 



The lietlnasphalt is cither perfectly opaque, or slin;htly 

 transparent at tlie edges ; the colour exiiihits every shade 

 of a mixture of yellow, grey, and brown, sometimes arran- 

 ged, in nearly concentric zones, so as to display the Ijcau- 

 tiful colours admirod in tlie. Egyptian jaspers, or disposed in 

 alteruiitc bunds, dots, spots, clouds, u^ in ilie other agates or 

 jaspers. 



It yields with more case to the knife than amber ; brealo 

 easily, exhibiting a perfect conclioidul fracture ; and some 

 varieties seem to be of the same hardness with amber, and 

 sufficiently hard and compact to receive a line polish. Other 

 varieties arc poious, having sometimes tlie appearance of 

 bone which has been long exposed to the action of the sun, 

 and being in that case also of a greyish colour. 



In lustre it is inferior to amber, having more of the lustre 

 of the gamboge, than that of copal ; and generally it seems 

 to be intermediate between these. Sometimes it is dull, jiar- 

 ticularly the porous variety. When homogeneous, comjiact, 

 and polished, it acquires by friction the negative electricity, 

 in the same degree as amber: the porous variety has this 

 property in a feeble degree. 



E.\RTHY RETINASPHALT. 



This usually occurs in fragments, or friable porous masses, 

 from the size of a grain of tnaizc and smaller, to that of u 

 walnut ; having a dull earthy as|)ect, intermixed with pyrites. 

 Its solidity docs not exceed that of clods of loam or of a stiff 

 soil, with which, externally, it has some resemblance ; and 

 like this sultstance, it cruml)les by friction between the fin- 

 gers. Its colour is grey, or yellowish grey, like ashes. IJy 

 exposure to heat it meits, and cxiiibits tlic properties of (he 

 ttrst variety. 



