Chap. 42.] Petroleum, AfpMtum y &c. 275 



more weighty than naphta, is much more common. It 

 is of a yellow or brown colour, and is found in Swit- 

 zerland, Sicily, Italy, and France. It iffues from the 

 crevices of rocks, or is found floating on the furface of 

 fprings. The different kinds of petrolea, on diftillation, 

 yield naphta, while a coaly refiduum remains in the 

 retort. 



BARBADOES TAR is of a thicker confiftence than/ pe- 

 troleum, and is alfo called mineral pitch j it was for- 

 merly found near Babylon, and conftituted> according 

 to Vitruvius, when mixed with lime, the cement 

 which was ufed in building the walls of that city. It 

 is at prefent found in feveral parts of Europe and in 

 America, where it drops, or diftils, gradually from 

 rocks. 



ASPHALTUM is a fubftance much refembling Barba- 

 does tar j it is alfo called J ews pitch, and is thrown 

 up in a liquid form from the bottom of the lake where 

 Sodom and Gomorrah antiently flood. From the 

 production of this fubftance this was called the Lake 

 Afphaltes, from a Greek word denoting bitumen. The 

 bitumen floating on the furface of the water is hardened 

 by the heat of the fun, and is in that ftate collected by 

 the Arabs on the more, where it is thrown. The 

 caftern afphaltum is feldom brought to Europe, but is 

 ufed by the inhabitants as pitch. 



All thefe thicker bitumens may be rendered thin- 

 ner by diftillation, and may be converted into an oily 

 fluid, the tenuity of which is increafed by the repetition 

 of the procefsj at every diftillation a quantity of char-* 

 coal, earthy matter, and carbonic acid gas, being fe- 

 parated from them. 



In Obferv attorn Jur la Pbyfique, for January, 1788, 

 vol. xxxii. M. dela Metherie makes mention of a mi- 

 neral elaftic bitumen analogous to the caoutchouc, or 

 T 2 elaftic 



