MINERALOGY. 



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

 Asia, and America. Naptlia when exposed to the light and 

 air becomes coloured, thickens, and nearly resembles Petro- 

 leum ; on distilling Petroleum, an Oil is obtained resembling 

 Naptha. 



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

 gen, and occasionally Nitrogen and Oxygen, and upon the 

 proportions of these are supposed to dep end the elasticity or 

 compactness of the substance. Elastic Bitumen is 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 

 thf" same purposes as Pitch, and is applied in some countries 

 to the cure of woundc. 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 in 

 France, Switzerland, Asia, and abundantly in the West 

 Indies. 



