Inflammables* 21 i 



SPECIES IV. 



Petrol^ Bergoel) Steinoel. 



Dodlor Pneftky has fhewn in the ^d vo- 

 lume of his Observations and Experiments 

 on Air, that eflential oils, l|ng expofed to the 

 atmofphere, abforb not only the pure part, 

 but alfo the phlogifticated part of it. An 

 abforption, which muft, in time, produce 

 confiderable changes in them ; by a procefs 

 of this fort, naptha is converted into petrol, 

 which is an oil of various degrees of denfity, 

 according to the time during which it has 

 been expofed to the atmofphere ; its colour 

 is reddim, or yellow, brown, greenim, or 

 blackilh, it is found trickling from rocks, or 

 iffuing from the earth in the Dutchy of Mo- 

 dena, and in various parts of France, Sivif- 

 Jerland, Germany, and Scotland^ as well as in 

 Afia. Alfo on the furface of the water of 

 different fountains, or mixed with earth and 

 fand, from which it is feparated by infufion 

 in water ; the thinneft fort poflefles the pro- 

 perties of naphtha, though in a lefler degree. 

 It is rendered finer by diftillation with water, 

 and leaves a refmous refiduum, and if dif- 

 tilled with a volatil alkali, the alkali ac- 

 quires the properties of fuccinated ammoniac, 

 and hence contains the acid of amber. Some 

 forts of it, according to Monet, are nearly 

 P 2 of 



