THE ROYAL ARTILLERY INSTITUTION. 
271 
oils and even of gas itself. Among the very earliest of these so-called 
mineral oils was paraffin oil, first obtained from a particular description 
of schist or coal, by Mr. Young; but some time before then, the most 
volatile products obtained by the distillation of coal-tar were employed 
in lamps without wicks, of such construction that the volatile liquid, 
flowing by gravitation from the reservoir to the source of heat, was con¬ 
verted into vapour as it reached the point where the jets of flame were 
produced. The great facility with which the more volatile portions of 
rock-oil or petroleum, and of the products of distillation from coal and 
schist, were applicable as brilliant illuminating agents in lamps of simple, 
cheap, and convenient construction, combined with the low price at 
which they could be retailed, consequent upon the great development of 
the petroleum industry in America, soon led to their extensive employ¬ 
ment by the general public, and the importation of these volatile oils or 
spirits attained in a short time a scale of considerable magnitude. 
The several varieties of so-called petroleum spirit which are known 
as naphtha, benzine, benzoline, gasoline, japannerY spirit, &c., yield 
vapour more or less freely on exposure to air at ordinary atmospheric 
temperatures, and even in some cases below 50° Fahr. Their low 
specific gravity and volatility permit of their employment in very simple 
and inexpensive lamps—the commonest form now extensively used by 
the poorer classes all over the country being the “ sponge lamp,” in 
which a small strip of sponge or coarsely plaited wick serves the purpose 
of drawing the spirit up from the reservoir to the orifice, where it is 
vaporised and burned. Although much the largest proportion of the 
petroleum spirit employed is probably used in lamps of some form or 
other, there are additional important uses to which it is applied in large 
quantities— e,g. 3 as a detergent, by dyers, &c.; as a substitute for 
turpentine in paints and varnishes; as a means of imparting’ luminosity 
to non-luminous inflammable gas, or of rendering atmospheric air itself 
the vehicle for illumination by saturating it with benzoline vapour; as 
a solvent and purifying agent in connection with the manufacture of 
artificial alizarine, &c. 
The statistics of the imports into London and Liverpool during the 
last three years show a very considerable increase in the consumption 
of petroleum spirit, as will be seen from the following numbers :— 
Barrels imported 
1872. 1873. 
33,693 45,889 
26,871 27,394 
1874. 
58,687 London. 
47,200 Liverpool. 
The imports of the less volatile and properly refined petroleum 
products, known generally as petroleum oil (also called kerosine, crystal 
oil, rock oil, astral oil, and, incorrectly, paraffin oil), which do not yield 
vapour below a temperature of 100°Fahi\, have fluctuated considerably 
during the last six years, but have increased lately to about five-fold 
into London, and four-fold into Liverpool, of what they were in 1872, as 
shown by the following numbers :— 
Barrels imported 
1872. 1873. 1874. 
{ 48,295 206,573 245,291 London, 
t 46,679 104,155 159,700 Liverpool. 
The so-called paraffin- or petroleum-lamp explosions, of which in the 
