MINERALOGY. 



places in England, and other parts of Europe, as also in 

 Asia, and America. Naptha when exposed to tlic light and 

 air becomes coloured, thickens, and nearly resen)bles Petro- 

 leum ; on distilling Petroleum, an Oil is obtained resembling 

 Naptha. 



Bitumen or Mineral Piicli, is composed of Carbon, Hydro- 

 gen, and occasionally Nitrogen and Oxygen, and upon the 

 proportions of these are supposed to dep.'nd the elasticity or 

 compactness of the substance. Elastic Bitumen i.s not heavier 

 than water, of a brownish tinge, and possesses a bituminous 

 odour, it burns freely, with much flame and smoke, and with 

 a gentle heat melts into a consistency of Naptha or Petro- 

 leum ; it readily takes out the traces of pencil in the manner 

 of Indian Rubber. 



Compact Bitumen is of a blackish colour ; one variety which 

 is moderately soft, and capable of receiving an impression 

 from the nail, is known by the name of Maltha; it is nearly 

 twice the weight -of water, and is occasionally used for 

 the s^me purposes as Pitch, and is applied in some countries 

 to the cure of wounds. When this substance is brittle and 

 hard it is called Asphalt, it gives out a bituminous odour 

 when rubbed, is opake, of a blackish brown colour, and 

 unctuous to the feel. This variety is used for the manufac- 

 ture of varnishes, particularly those kinds used by Engravers, 

 it is also mixed with grease, and when gently heated, used 

 for paying the bottoms of ships, and is considered as a pro- 

 tection against the Teredo or Ship-Worm. It is found iu 

 France, Switzerland, Asia, and abundantly in the West 

 Indies. 



