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XLV. New Method for purifying Coal Gas, and at the same 
time increasing the Product from a given Quantity of Coals. 
By Mr. 38. Parxer, Liverpool. 
To Mr. Tilloch. 
Sir, — Havine noticed in your number for April last, a sin- 
gular method of purifying coal gas, I take the liberty of com- 
municating to you some additional facts which cannot be wholly 
uninteresting to those who are engaged in the new and wonder- 
ful art of procuring light. Having made the crude coal gas to 
pass through an arrangement of three iron pipes placed hori- 
zontally in a furnace, and kept at a dull red heat, being con- 
nected together with a gun-barrel ; I found to my great astonish- 
ment that the quantity of gas that could be obtained by this 
means from a given quantity of coal greatly exceeded the quan- 
tity obtainable in the usual manner; and further, that the gas 
was perfectly pure, whilst the quantity of tar produced during 
the process was considerably less than what is obtained in the 
ordinary gas-light process. The fluid, which was collected in a 
vessel interposed between the extremity of the ignited iron pipes 
through which the gas passed, and the gasometer which received 
it, contained no vestige of ammionia; but on the contrary, it in- 
stantly reddened litmus paper. It possessed an acid styptic 
taste, and a pungent sulphureous odour. It was of a black colour; 
and when largely diluted, produced an insoluble precipitate with 
muriate of barytes. It was sulphuric acid. It is therefore evi- 
dent that crude coal gas, when made to traverse an ignited iron 
tube, suffers a remarkable change. The sulphuretted hydrogen 
gas, which always accompanies this gaseous fluid as obtained 
from coal, no doubt becomes decomposed during the process, 
and to it the production of the sulphuric acid must be attributed ; 
—but by what means this decomposition is effected, would not 
becoine me to state. It is evident that not only the sulphuretted 
hydrogen, but the ammonia also, is decomposed ; hecause the 
fluid which distils over is not alkaline, but decidedly acid. And 
muriate of barytes and acetate of lead show that it contains 
sulphuric acid strongly loaded with sulphureous acid gas. 
The increase of gas, there can be no doubt, must be attributed 
to the decomposition which the tar suffers during this process ; 
for it is sufficiently evident that this substance may be wholly 
converted into oxycarburetted hydrogen gas. 
The gas thus produced is perfectly free from sulphuretted hy- 
drogen, as well as from carbonic acid ; for it neither disturbs the 
transparency of a solution of super-acetate of lead, nor barytic 
water, when made to pass through it. From these considerations 
there 
