FURNACE, 
angle with the fide of the furnace. From what has been 
previoufly gaa the high afh-pit will contribute much 
to its actior. It s alfo recommended that the chimney 
fhould bedo 
Fig. 2. sn a fection of a portable air-furnace, 
adapted to general purpofes : a J is a frame of caft iron ftand- 
ing on three legs; ca difh of rolled iron for the afhes to 
fall into; ao the top of the frame, has a hole in the centre 
a little wider than the fire-place, into which t te is 
fitted ; dis a groove paffing quite through the frame, a little 
the middle, and immediatety under 
the grate. Different pieces of fheet iron are made to fit 
this groove, og different ies pees for the purpofe 
of ar a ing the draug : the.n, new ch has no 
opening, and is intende out the air en I 
openings in thefe ae fides bei Cy the 
air will enter the furnace perpendicol ly and ae paifage 
will be much raphael by the height of the grate from the 
floor, and by the air having a free accefs on all fides to the 
furnace. 
i & is the fire-place; e the cover, ee of yaaa one 
round brick made on purpofe, fitted i es “iron fram 
of feveral pieces ae into the Ga, h 
rolled iron, lined with a connie o 
a 
t and, and one of lime. The 
pee gs is alfo of rolled iron, and confiits of double tubes, 
oand pq, r rivetted to the out fide ofthe furnace. Thee: 
faves the tubes is filled with the above-mentioned compo- 
fition. ‘The other parts of the chimney, when it is required 
to increafe its height, may be made in pieces of about two 
feet in aK coniifting, like the parts attached to the fur- 
nace, of a double tube, and the cavity filled up as before 
direCted. The inner tube mutt be a little fhorter than the 
t 
outer tube, fo that the additional lengt the outer tube 
may form the joint in putting the chimney together 
hole is made in th the furnace at i, and a fimilar 
one on tl pofite fide, for the purpofe of introducing 
tube through the furnace, which is required in ri 
ments. A flit is alfo made in the furnace at 4, for the 
purpofe of introducing the neck-of a retort. The hole - 
flit above-mentioned have correfpondent plugs made of t 
fame fubftance as the lining of the furnace, by which cons 
openings are clofed when not wanted. There is another open- 
d by the plu - this is ufed for the introduc- 
1 whe ee convenient to introduce it at i 
uth of the furnace. on ufionally, alfo, a fmall n 
may be intr oduced into it at this opens: ie other er of 
-cath mug es ig in- 
picks 3, Plate LI. 
—_ a retort is iutrodaced, and the bottom c - nee 
happen to be fupported by the fuel, it is hable to move 
te fometimes a be broken, by retting varel upon the 
convenience may be remed y paling a 
fold plug hrough bal furnace at 7 his plog ray 
e by coating a of iron with a compound of ver ie 
pie clay aaa fan ] coe it as infufible as poffible, fince 
it will be expofed to the greateit heat of the furnace. 
middle of this fupport mult contain a recefs to receive te 
bottom of the retort. — - me 
and a flide introduced a 
powerful mcg ee and, by introducing different fides, 
it may beem , 
, e ca eee reprefented in Piate 1. jig. 3, is principally v 
intended for enamelling and aflaying in the cupel, where the 
exclufion of every thing but the air oe the atmofphere is par- 
outfide of. the : 
aera neceflary: a is an iron frame, fimilar to that of 
ig. 2, having a groove at d, for the fliding era to o regu 
a the draught, and a tray at e to receive the ea 
e body of the furnace, made. 0 
fmilar to that of jg. 2, leaving the fae mn for the fire- 
place; gp is a dome connected at p by a fliding hoop, with 
the chimney w 3 s isa circular damper ; f isa mufle, sip 
a plug at ¢; ¢ is the a earthen tube flanding upon 
grate, having an opening, Z, quite through it, which cor- 
refponds with a fae openiug in the bottom of the mufile. 
This tube alfo ferves as a fupport for the muffle; wv is an 
opening through the ase of the furnace, essen 
with a fimilar a in the end of the muflle. e end of the 
muffle is made c ioe as accurately to fit the fide of the 
concave. fire-place NCe, % of air wi'l pais up the 
we cu 
are He into the ie. nich will ef fuse at the opening, -r, 
into the chimney /, This current can be regulated by the 
circular damper g. The plug, e, is only to be taken out to 
infpeét the proceis, the damper, Q being at the fame time fhut 
to ie the entrance of cold air into the mu iffle. 
vantages of this 
in 1g, are obvious, 
cety. When the cold 
muffle, or the heat of the furnace is deficient, the damper, qs 
can he fhut more or lefs ; and if the heat is Pe great, that at 
g may be opened, and s ‘fhut to a any degree 
This furnace may very eafily be Sonn into a mclting- 
furn — or even to one for general purpofes. The dome. 
§p; and the mufile f, being- removed, and a cap put upon 
the mouth of the chimney w, the furnace hayizge a cover 
fimilar to that of fig.2: the plug, y, being removed, wilk 
ee 
orm the flue, the opening, «, eing of no conlequence; 
particulany oo pane damper, g, is fhut ; and a plug mutt 
roduced a where the muffle was taken out. "Uhe 
ae may be lengthened from the part z by pieces fimilar 
to thofe recommended ir 
An_air-furnace, on Ae common plan, is reprefented in 
Plate Il. fig. 2, in which ac is the fire-place ; c¢ th 
é the cover; d the flue; and e the chirnney. 
iffers from the air-furnace alr eady deferibed only in the 
aera of the flue, and afh-pit. 
ed by Mr. eee is pies in 
a 
for the purpel a of ee aes ae ee ; y a 
paflage for the air into the chimne ey bs andiis a ‘fiding 
damper. Al-hough this furnace poflefles g-eat conveniences, 
it is not calculated for producing the ¢ createlt degrecs of leat, 
fince the air muft meet — much obftr ructicn in its pallage 
from the fire-place ney. Fig. 4. is a furnace in- 
vented r. Muthet, ieides as an ia imental furnace 
r the purpofe of affayi ng ores, &e.t a isacyl'n 
cait iron, lined with fire-Uricks, fo as to conttitute the ne 
placeef; y is the grate having a recefs in the pos for t 
recepito 1 of a crucible ftand; s the a -pit 3 0 e flue, 
ni th: cover: 4713 a rod of fteel fattened into t e ary om 
of the caft iron cylinder at 4, and having at the other end an 
index i &, fitted to the arc gr, which is attached to the cylin- 
er. When the furnace is ated, the excefs of expantion of 
the ftee! rod above the cait iron cylinder will give motion 
to the index, and if the arc be hapa foas to > correfpond 
with Wedgwood’s hes ete is - Soest @ of heat, ina ” 
periment, will b known. to meee the ae i 
which i is polite, ‘from ‘oxydation,, it is inclofed ina t 
af) 
