On the Purification of Coal Gas. 263 
the gas, if I may so term it, I do now, as I then stated, 
“ pass it through lime-water.’ Having explained thus much, 
I can with pleasure proceed hand-in-hand with Mr. Bolton in the 
flowery path of experiment. We all have, or are likely to have, 
our hobbies. Chemistry has been the one which from early youth 
has filled up and rendered both pleasant and profitable the hours 
of relaxation from more weighty concerns. Like Mr. Bolton, I 
have visited many gas concerns, both great and small, and can 
bear witness with him to their often total want of skill, and to 
the consequent impurity of their gas; to say nothing of the im- 
mense expense of outfit, and wear and tear. In some establish- 
ments I have seen retorts worn out in three days; some in three 
months; and others, though in constant work, (as at a friend’s in 
Birmingham,) not in three years! This speaks volumes as to the 
necessity of a good plan, and to the effects of the want of it. 
Tt puts me in mind, Mr. Editor, of the pledge which I gave 
in my former letter, of troubling you with a sketch of the plan of 
the apparatus we were then setting up, to light our brewery, 
offices and house. It is now complete, end that in every sense. 
The gas is brought to a red heat, in connexion with oxidizeable 
surfaces, or not, at pleasure, lefore leaving the retort, and its 
quality is as above described: it then passes through a condenser 5 
and lastly, through lime-mud into the gasometer. 
I am fully convinced with Mr. B. that there is nothing so 
cheap, so simple, and so effectual, as lime for purifying. The lights 
of two Argands by which I am writing, have been burning at least 
five hours, and the room is as free from any unpleasant smell as 
if two wax-lights had been burning!—Among other chemical 
tests, the nose is not abad one.—But it is a great point that the 
lime-washer should be furnished with an agitator to stir up the 
thickest and most serviceable part of the lime, which otherwise 
will form a stiff inert ass at the bottom. ‘This appendage seems 
to be wanting in the sketch of Mr. Clegg’s washer. The washer 
we have adopted, you will, I trust, consider as combining in some 
degree the main requisites of exposure of surface with moderate 
pressure, united to simplicity and cheapness of structure, as well 
as being portable; which, on the small scale of a private gas ap- 
paratus situated near a dwelling, will be found a great desidera- 
tum; as thereby the nuisance which invariably takes place at 
recharging with fresh lime, is removed to a distance. ‘The ac- 
companying sketch A A (Plate III. fig. 1.) represents the section 
of an eighteen- gallon cask, which may be had fora few shillings, 
as it does not require that it shall be a sweet one, though a sound 
one in point of leakage. 
This cask contains the lime mud; 0 is the handle of the agi- 
tator, which is made to take off aud on, and is fastened with a pin 
R4 or 
