BITUMEN. 
455 
Rhine. Wells are dug in some of these places 
120 feet deep, where they find the petrol mixed 
with sand in the proportion of about ten pounds in 
the hundred weight. To extract the bitumen from 
its earthy bed the workmen put the sand into large 
coppers, where it is mixed with water and boiled. 
The bitumen separated by this means is afterwards 
distilled, and pure petroleum obtained from it. 
At mount Zibio near Modena, in Italy, the 
springs containing petrol are situated in the bottom 
of a valley, and are enclosed by a friable rock, com- 
posed of a mixture of clay, chalk, and sand. The 
petrol swims on the surface, but scarcely makes its 
appearance in the winter, when the water is most 
abundant. Wells are dug to receive the water of 
the springs, from whence the floating petrol is 
drawn up in buckets. 
In India , the kingdom of Ava produces abun- 
dance of petrol. The principal place is on the river 
Ava, about three miles from Erraouaddy, where it 
is said there are five hundred wells in one hill. At 
about 180 feet below the surface of the ground they 
find a bed of coal, from whence the petrol proceeds, 
and this is drawn up from the bottom of the wells 
in iron buckets. The heat of those wells is so 
excessive, that we are assured the workmen are con- 
stantly in a state of perspiration. 
England produces this mineral, and some is 
found in Scotland, but not in such abundance as in 
other countries. 
