122 IMPROVEMENTS IN THE MANUFACTURE OF GAS. 
power 75 per cent, greater than that of ordinary gas, and 
free from the usual impurities. 
The process adopted by the Western Gas Company is 
that which has recently been patented by Mr. G. H. Pal- 
mer. The specification (dated Oct. 17th, 1847,) describes 
the construction of furnaces said to be calculated to insure 
an equable temperature with tubes called regenerators, 
passing'through the upper part of the furnaces, by means of 
which the gas is exposed to a dull red heat during its pas- 
sage from the retort to the condenser. These, regenerators 
contain a quantity of metallic chippings or loose plates 
of iron, the object of which is to increase the heated sur- 
face over which the crude gas passes. This part of the pro- 
cess is intended to deprive the gas of sulphur and some other 
impurities, and to increase its bulk and illuminating power. 
For its further purification it is made to pass through a 
"mechanical precipitator and cooling apparatus,^' in which 
a revolving fan keeps it in constant agitation, and causes 
the deposition of the tar and naphtha which runs out below. 
It next passes into " filtering towers," in which jets of liquid 
ammonia are thrown into it ; after which it is introduced 
into a vessel in contact with steam at a high temperature, 
with which it is mechanically mixed. The mixture of gas 
and steam is then introduced into a refrigeratory or con- 
densor, and the operation of steaming and condensing is re- 
peated until all the condensible materials in the gas are 
separated. In addition to the above manipulation, the 
gas is also subjected to the usual purification with lime, in 
which Mr. Palmer describes an improvement, namely, the 
introduction of a blast of air prior to the removal of the re- 
fuse lime from the apparatus. Lastly, the specification 
describes a process for naphthalizing or denaphthalizingthe 
gas by the introduction of naphtha or fixed oils into an ap- 
paratus resembling that which is used for treating the gas 
with liquid ammonia. 
