tumen in its greatest purity, is a very thin, yellowish, but some- 

 times colourless oil, of a strong, but not disagreeable odour. It is 

 so highly inflammable, that it catches fire, even on the approach of 

 flame; burning freely, with a large white flame, and leaving 

 scarcely any residuum. Its specific gravity may be taken at .8475 

 from Brisson. It does not freeze at 0". Fahrenheit, It is insolu- 

 ble in alcohol. By exposure to the air, it becomes yellow, and 

 then brown ; and at the same time acquires a greater degree of con- 

 sistency ; passing into petroleum. It is found in great abundance 

 in Persia; it sometimes is found on the surface of the waters of 

 springs, and sometimes issuing from certain strata. 



PETROLEUM is a tenacious, brown fluid, which, according to the 

 length of its exposure to the air, increases in thickness, and in dark- 

 ness of colour ; until it acquires nearly the viscidity of common 

 tar: its smell, at the same time, becoming less pleasant. In this 

 state, although highly inflammable, it burns, with a flame less clear 

 and white, yielding a soot, and leaving a small quantity of coaly 

 residuum. Specific gravity, .8783, Brisson. It is also found in 

 Persia, and likewise in many parts of Europe. 



MOUNTAIN OR MINERAL TAR is the name given to this sub- 

 stance, when it has acquired the consistency and colour of common 

 tar. It emits a strong bituminous smell, on being burnt. Specific 

 gravity, 1.1. 



MINERAL PITCH and MALTHA, are terms employed to mark 

 the different higher degrees of colour and consistency, which this 

 substance possesses in its further inspissation. Whilst so soft as to 

 possess some degree of tenacity, it is called mineral pitch; but when 

 it has become almost black, and so hard as neither to stain nor ad- 

 here to the fingers, it is termed maltha. Its specific gravity varies 

 with its degrees of induration, and with the quantity of earth it 

 contains. 



ASPHALT UM appears to be the same substance, in its highest de- 



