60 PHYSIOGRAPHY. 



Bitumen. 



Oil is first inspissated, and then it is changed into Mineral Pitch by fur 

 ther exposure to the air. Naphtha embraces yellowish and nearly trans 

 parent varieties of the fluid Bitumen, while Petroleum consists of thos 

 which have the consistence of tar, together with a black color. Elasti 

 Bitumen is distinguished by its elasticity. Earthy Bitumen has an ear 

 thy fracture, while Asphaltum possesses a more or less conchoidal frac 

 ture. Still, all these varieties are joined by transitions, which prove 

 that they form but a single natural historical species. 



2. Mineral oil is easily inflammable, and burns with a white flam< 

 and much smoke. Also the Mineral Pitch is very inflammable, an< 

 burns with a bituminous smell ; some varieties melt in a higher tempe 

 rature. 



8. Analysis* 

 By THOMSON, 



of Naphtha. of Elastic Bitumen 



Carbon . . 82-20 .... 52-25 



Hydrogen , 14-80 .... 7-49 



Azote . 0-00 .... 0-15 



Oxygen . 0-00 .... 40-11 



4. The fluid varieties of Bitumen ooze out of several rocks, as sand 

 stone, slaty clay, &c., or they are found on the surface of springs anc 

 lakes. The elastic variety is found in limestone rocks along with Gale- 

 na ; the earthy in beds with limestone, but associated with members o: 

 the coal formation. The Asphaltum is imbedded in nodules in limestone, 

 in agate balls, in veins with Galena, Fluor, Sec. ; also in beds, and on the 

 shores and waters of certain lakes. 



5. Fluid varieties have been found in various districts of Italy, in Si- 

 cily, in Zante, in the Caspian Sea, in Persia and other countries in Asia, 

 Elastic Bitumen (sometimes called mineral Caoutchouk) occurs at Cas- 

 tleton in Derbyshire. Earthy Bitumen is found near Neufchatel in 

 Switzerland, at Grund in the Hartz, in Dalmatia, &c. Asphaltum forms 

 nodules in limestone at Bleiberg in Carinthia, in sandstone in Albania, in 

 great abundance in the island of Trinidad, and in large pieces on the 

 shores, or floating on the surface of the Asphaltic lake in Judea, called 

 the Dead Sea. 



The United States and the Canadas afford numerous localities of the 

 more fluid and soft varieties of Bitumen. Petroleum occurs on the Ken- 

 hawa in Virginia, on a spring of water five miles from Scottsville, Allen 

 co. (Ken.) at several places in the western part of Pennsylvania, at Duck 



