4,0 6 Mr. Hatchett’s Observations on the Change 
elastic bitumen from Derbyshire; on the genuine asphaltum; 
on very pure cannel coal; and on the common pit coal. 
100 grains of each were digested with three ounces of 
alcohol, in matrasses placed in warm sand, during five days, 
some alcohol being occasionally added, to supply the loss caused 
by evaporation. After the abovementioned period had elapsed, 
the liquid contained in each matrass was poured into separate 
vessels. 
i. The alcohol which had been digested on the elastic bitu- 
men was not tinged, nor, when spontaneously evaporated, did 
it leave any film or stain on the glass. 
ii. From asphaltum, the alcohol had extracted a yellow 
tincture, which, in some situations, appeared of a pale olive 
colour, and, being spontaneously evaporated, a^ thick brown 
liquid was deposited, in small drops, on the glass ; these drops 
did not become hard after two months, and possessed the 
odour, and every other property, of petroleum. The asphaltum 
had lost in weight about one grain and a half. 
hi. The cannel coal had communicated a pale yellow tint to 
the alcohol, which, in the manner above described, was ascer- 
tained to be caused by petroleum ; but, from the smallness of 
the quantity, the weight could not be determined. 
iv. The alcohol which had been digested on pit coal, had 
not assumed any colour; but, by spontaneous evaporation,* it 
left a film on the glass, which, by its odour, was also found to 
be petroleum. 
By these experiments we find, that the action of alcohol on 
the bitumens is very slight ; and that the small portion which 
* Spontaneous evaporation, by exposure to the air, was employed in these experi- 
ments, for reasons which must be sufficiently obvious. 
