<J48 WONDBRS OF ART. 
diminishes, the weight of the gasometer expels its contents, 
the balance- weight not being quite so heavy as the gasome- 
ter, in order that a suitable pressure may be exerted td force 
die gas out at the burners witli a proper jet. 
The gas, after it leaves tlie deposit-vessel, and before it 
.taches the gasometer, is passed through a vessel of lime- 
Ivater, to deprive it of every bituminous and sulphureous 
hnell. From the gasometer it enters a tube by small holes 
aiade at its top, and, passing on through other tubes, is 
conveyed by pipes to. the burners, or lamps, where it is to 
be consumed. These burners are formed in various ways, 
cither by a tube ending with a simple orifice, at which the 
gas issues in a stream, and, if once lighted, continues to 
burn with a steady and regular light as long as any gas is 
supplied. At Other times a number of very minute holes 
are made in the end of a pipe, wliich form as many jets de 
feu, and have a very brilliant appearance. If the gasoraetei 
of a gas-light apparatus has a diameter of five feet, by seven 
feet high, it will contain a sufficient quantity of gas, at four 
cubic feet per light, per hour, to give forty hours light to a 
brilliant Argand lamp, or five hours to eight lamps, equal 
in intensity to one hundred and sixty common street oil- 
lamps. Such a gasometer will be filled by the distillation 
in the retort of about half a bushel, or a quarter of a hun- 
dred weight, of coals. The remains which are found in 
the retort, after the process is finished, consist of most ex- 
cellent coke, which in value, for culinary fires, or manu- 
factories, returns a considerable portion of the whole 
expences. 
The experiments made by Mr. Brande, in a .small gas appa- 
ratus erected in the laboratory of the Royal Institution, lead 
to the conclusion, ti;at a chaldron of good Wallsend Ne\v- 
castle coals would afford from 17,000 to 20,000 cubic feet 
of gas } but the process of distillation, as it has been carried 
on in the large establishments for lighting the metropolis/ 
has seldom afforded a larger average produce than 12,000 
cubic feet. There can, however, be little doubt that, bV 
improvements in the construction and management of the 
retorts, the highest of the above averages may be obtained. 
In the month of April, ISlO, at the three stations belong' 
kig to the chartered Gas-ligiit Company, situated in 
Street, Westminster, in Worship Street, and in Norton* 
