146 , NAPHTHA. 
mixture is apt to explode. To obtain a light, nothing 
further is requisite than to dip a match, thus formed, 
into a bottle containing the acid. 
BITUMEN FAMILY. 
212. NAPHTHA, or ROCK OIL, is a ycllwv or brownish 
bitwninoite'Jluid, of strong penetrating odour, somewhat greavt/ 
to the touch, and so light as to float even on spirit of wine. 
By exposure to the air, the consistence of naphtha is in- 
creased, and it passes into petroleum ('213). 
There are copious springs of naphtha at Baku, on 
the shore of the Caspian Sea ; and also in some parts of 
Italy, particularly at Monte-Chiaro, near Piacenza. At 
Pitchford, in Shropshire, extensive strata or beds of 
sandstone are saturated with this mineral fluid, which is 
obtained from the stone by distillation, and is sold, as a 
remedy against sprains and rheumatism, under the name 
of Bettons British oil. 
By the Persians and Russians naphtha is used inter- 
nally as a cordial. On the shores of the Caspian it is 
burned in lamps, instead of oil ; and, in some parts of 
Italy it is employed in the lighting of churches and 
streets. When mixed with certain vegetable oils, it 
forms an excellent varnish. 
It is the property of naphtha to take fire on the ap- 
proach of a light, and to burn with great readiness and 
a white flame, leaving scarcely any residuum. The 
town of Broseley, in Shropshire, was formerly celebrated 
for a burning spring, which was first dicovered in the 
month of June, 1711. Its original issuing from the 
ground was announced by a terrible noise in the night, 
which awakened several persons who lived near the spot. 
Some of these, on going out to ascertain the cause of 
the alarm, perceived, about two hundred yards from the 
river Severn, an extraordinary shaking of the earth, and 
a little bubbling of water through the grass. On digging 
round the spot, the water sprang up to a great height, 
and a candle which one of them held in his hand, set it 
on fire. This circumstance excited great curiosity; and 
