LIGHT. 685 
elbow, B, goes into a water-joint, formed of a tube af¬ 
fixed to the cover of the purifier C; and another tube, 
which paffes through the lid of the purifier. The elbow- 
pipe then goes over the inner tube ; and, when put on, 
the jointing is made good by pouring water into the fpace 
between the tubes, which renders it air-tight. The gas, 
ss the arrows fliovv, paffes down into the purifier C, which 
is rather more than half full of water; the ufe of this wa¬ 
ter-joint is for the convenience of removing the lid d, to 
which this pipe is attached. The purifier C is a wooden 
trough, with a fheet-iron top, to which the tubes are fol- 
dered ; and it is faftened to the trough to keep all fe- 
cure and air-tight. The (beets of iron, e, f, g, k, i, k , are 
alternately foldered to the iron top, and faltened to the 
wooden bottom. Now, when the trough is half filled 
with water, the gas pafTes into it at B ; and, as it can only 
find its way out again at R, it muft pafs through the wa¬ 
ter. The inner pipe B reaches under the furface of the 
water in the trough ; now, when the gas is forced into 
the water, it would rife to the top of the purifier, and go 
along in a body to the end, and out at the pipe R, 
if the Greets of iron, e, f, g, h, i, and k", which hand 
acrofs the trough with openings in them, alternately at 
top and bottom, did not flop it, force it to defcend into 
the water, and hinder it from going any way but through 
thefe apertures, purifying it all the time it is paffmg 
through the whole body of water, until it is properly 
waftied ; it then efcapes through the pipe R at the end of 
the trough C ; then paffes down the pipe S, and is car¬ 
ried up into the refervoir, or gazometer, K. In the bot¬ 
tom or the purifier is an aperture, clofed by a plug at D, 
to let off the ammoniacal water and tar as it is depofited, 
and the pipe, with the cock E at the top of the purifier, 
is to burn away the fpare gas when not to be ufed. 
There is a ftop-cock placed in the main pipe at F, that, 
■when the refervoir is full, and gas is making, and cannot 
be ufed, the cock may be turned, and prevent any gas 
from paffing from the refervoir; and, by opening the cock 
E on the top of the purifier, and firing it, all the gas 
which is made more than is wanted for ufe may be burnt 
away. If this were not done, the gas would continue to 
find its way into the refervoir K, which would overflow, 
and produce a difagreeable fmell; which this Ample way 
of burning it away as fall as it is made, when not wanted, 
prevents. It may in fome meafure happen, that, although 
the gas has paffed through the purifier C, yet that a final! 
portion of tar will pafs along with it, and would either 
clog the pipe S, or accumulate in the refervoir. To avoid 
thUv there is placed at the bottom of the pipe S at G, be¬ 
fore it rifes into the refervoir, a jar into which a pipe, 
made as fhown in the engraving, condufls the tar ; this 
collefts all that paffes through the purifier ; it is filled 
with water, over which the gas paffes up into the re¬ 
fervoir ; but the tar drains down tins lead pipe, and de- 
pofits itfelf in the jar of water. The longer this pipe S 
is, the better, fince it ferves as a refrigeratory. H is a 
plain cafic, made to any proper fize, and filled with water, 
with a cock to draw off the water when it becomes foul. 
The upper veifel K is made of (beet-iron, rivetted toge¬ 
ther in the manner engine-boilers are made. If it be only 
from five hundred to one thoufand gallons in fize, it will 
require only two crol's iron bars at top, and four ribs 
down the fides to keep it in firm, with a ftrong ring at 
top; and, as there i-s no ftrefs oh this veffel, it will afeend 
and defcend eafily without any other fupport or framing, 
the plain (heet-iron fides being rivetted to the four ribs, 
and it is quite open at the bottom. A ftrong rope runs 
over the pulleys LL, with a weight M to balance the vef¬ 
fel K, and afiilt it in rifing and falling. The pipe I is that 
through which the gas paffes from the refervoir, or ga¬ 
zometer, and, rifing through the pipe T, is conveyed to 
all parts to be lighted. There is alfo another drain-pipe at 
N; for, after all the wafhing, See. a very fcnall portion of 
tar and moilture may rife into the pipes, and perhaps in 
time clog them ; but, by laying all the pipes in the firft, 
Vol. XII. No. S63. 
fecond, and third, dories, on a fmall defeent, if any tar or 
moilture ftiould rife, it will drain down all the pipes 
from top to bottom, and be depofited in the earthen jar 
at N ; and by this means the pipes will not clog up in 
half a century. Thefe jars muft be fometimes removed 
and emptied, freflr water put in, as alfo the water in the 
veffel H muft be changed, to keep it clean and fweetj 
and the water in the purifier C ftiould be changed every 
two or three days: by thefe means the gas will be de¬ 
prived of all its fmell, at lealt as far as walhing will effect 
it, and the apparatus will be clean. 
The ftop-cock at O is for the ufe of a mafter, if he 
wifties to lock up the gas in the refervoir, to prevent his 
workmen, Sec. wafting it in liis abfence ; as alfo, if any 
pipe fliould leak, or a cock be out of order, in any part of 
the premifes, by turning this cock all the gas is kept in 
the refervoir while the pipe is repaired, or any other al¬ 
teration made ; it alio extinguishes all the lights when 
turned, if any are left burning by carelefs workmen; nor 
can they be lighted until it is opened again. 
The whole of this apparatus is Ample, and not liable to 
be put out of order in fuch a way but that any perfott 
may put it to rights again. All the art required to make 
the gas, is to take off the cover of the pot, and, without 
removing the pot, to take out the coke, and fill it with 
freflr coal, wedge it down by putting an iron wedge be¬ 
tween the bewels or ears and the elbow of the veifel, and, 
if required, plafter a little clay or loam round the cover, 
to keep it air-tight; a fire is then made under it, and the 
whole is done. The boy or man who does it muft now 
and then look at the fire, and keep it up, until the pot is 
hot, and the gas is made. In works where lights are 
wanted almoft always, I would recommend two fire¬ 
places, and two pots, fo that, when one pot is burned out, 
the other pot may be ready to a<ft ; for this purpofe the 
purifier muft be provided with two of the water-joints B, 
one communicating with each pot, and the elbow-pipe of 
each pot muft have a ftop-cock, as V ; then, when one 
pot is burning, the cock in the other pipe muft be flopped, 
that the gas may not find its way out of the purifier; 
and, when all the gas is extracted from that pot, the cock 
C, leading from it, muft be (topped, anct the pot-left to 
cool; while a fire is put under the other pot, its cock is 
opened, and a fupply of gas from it is palled into the re¬ 
fervoir; by tliele means one of the pots is conftantly Cup- 
plying the refervoir with gas, and the lights are always 
kept burning. One purifier is all that is neceffary ; the 
cock V muft be (hut when either of the covers are taken 
up to fill the pot again with coal. When the elbow-pipe 
is lifted out of the water-joint, as the cover is attached to 
it, a plug muft be provided to fit into the water-joint pipe 
the moment the elbow is removed from it, or the gas will 
rufh out of the pipe at the water-joint; but a better way 
would be, to lengthen the pipe o( the water-joints B, and 
place a large cock under each of them, almoft clofe to the 
top of the purifier. When one pot is burnt out, by turn¬ 
ing the cock it keeps all the gas in the purifier while the 
cover is removed ; no plug is neceffary in this method. 
When people are very particular (efpecially when houfes 
or counting-houfes are to be lighted), and wilh all fmell 
to be deftroyed, if they are not fatisfied with waffling it, 
and ftill think there is a little fmell left (and very little 
indeed, if any, v\ill be left) after the wafhing, a fmall 
trough may be added, made in the fame way as the puri¬ 
fier, with (beets of iron acrofs to force the gas through 
the pipe R communicating with it. This trough may ba 
filled with water, with a few lumps of lime put into it, 
and this water and lime changed often : on the gas being 
forced through this lime-water, if there was any remain¬ 
ing fmell in it, this would completely take it away; and, 
as has been before obferved, by changing all the waters 
now and then, and keeping this fmall trough conhantly 
fupplied with clean water and lime, the gas after palling 
it will afeend the pipes to the lights pure. 
Mr. Cook, by means of his apparatus, has produced 
S M (everal 
