FURNACE. 
ferted, a blaft- furnace would be et differing from an air- 
ay only in the mode o ing the air into the fire 
Indeed its action would be fo fi milan to that of an Seefin 
that it might for mot purpofes sy ae the fame 
“The blaft-furnace for ears a ay eel was much 
the ing ew a black- 
so The 
the largeft fize, and if a cover or dome, or an additional part 
be wanted, another pot with a portion of its lower narrow 
part fawed off makes a very convenient one. A r 
plate or flip fawed off from the folid part of che etn 
ferves very “commodior ifly both for a grate and for a fupport 
to the crucible; eight or nine holes, about three quarters 
ofan ‘neh | in diameter, are bored round the outer part of the 
late for the tranfinifiion of Ls air forced in by the bellows, 
which holes a n downwards to prevent their 
being choaked up by pieces ‘of a. fuel. The air was forced 
in ae bellows by an aperture on the fide of the po 
erations which require‘a confiderable degree of con- 
‘tentr a heat, it has — prepofed to ae a number of 
flames into one point by ftreams of air drive n fr om different 
parts of the circumference of the fuel s the middle by 
means of ese bellows placed round the furnace. But a 
number ellows being in odio r. Lewis has con- 
ro 
trived to multiply the ftream of air from one bellows. The 
pot which ferves as a furnace for this purpofe has a number 
of holes bored at {mall diftunces in {piral lines all over it, 
— a bottom up to fuch height as the fuel is defigned to 
rea 
The euch is placed on a proper fupport in the bottom ; 
and the holes are sree directed towards the crucible, 
piral pe its 
pot fo ae that 
ete has no other outlet t 
bellows s and therefore the air 
itfelf through the aaa on of the in ot. 
rthur Aikin has cone eee im oe upon this 
plan o of Dr. Lewis’s, ad the following is a defcri sa of his 
sata as publifhed in the shoe y ee Magazin 
+ fig. 3 isa view of a fection of ae furnace. 
It is formed of three black-lead crucibles. The 1ft, a, is a 
off near to the bottom, leaving a portion of the 
what contains the fire and the 
purpofe of introducing an iron initrument to lift it on and 
This furnace is particularly adapted for a leGture room, 
{ince its fire can be raifed to its full heat in a very little time ; 
at the fame time it is Pe sae of producing a greater r heat 
than almoft any other fur 
Mr. Aikin has se nn furnace to experiments with 
‘the cupel, by having a crucible with a hole through the bot- 
& 
the cover extending obliquely out of the mouth of the furs 
nace ;_ this ferves” to look down for infpecting the pro- 
cefs. 
everal kinds of {mall blaft furnaces are alfo ufed in the 
arts, particularly that ufed in melting pig iron for the pur- 
pole of calting. oi furnace is called cupola, and will be 
defcribed under iro See Ino 
URNACES for ee Colours, are thofe for fubliming 
cinnabar or fulphuret of mercury for making vermilion ; 
for fubliming fiphut of arfenic for making king’s yellow ; 
for calcining blood for ma oo Pruffian blue, chr: &e. &C. 
For their co os an ad ufe, fee the arts, and the dif- 
ferent gieeea in this w wo 
eee itreet, L 
of Wales, to prefent our a and artilts o 
Ww ith a drawi ing of the furnace which he has at! red 
fatcly fay, have not been equalled 
colour and accuracy of defign, or for the fize to which he 
has extended the paintings on enamel, which were formerly 
confined to the moft minute fubje&ts. The lower part of 
V. contains aia drawings, which are two vertical 
f{eGtions taken on planes perpendicular to each other; the 
ers of ae applyiag to both. A reprefents 
he fae ; the 
fire door at 
back of the te nace or fide sy aie to that where the ope- 
rator is ftat: and in a feparate room: this is intended 
that the Gnoks, otek will a. aes iffue from the mouth 
pictures. pai room, 
d,h 
s cpen only at one end ; it is fu 
arches, I, F, brick-n on extending acrofs the furnace ; 
the fpaces ene eee form three flues, which convey the 
flame of the fuel beneath the muffle. The mouths of thefe 
flues are fhewn by the three dark fquares fg. 113 they then 
turn up over the arched roof K,, of the fire-place, and under 
the muffle between the arches I’, F, F, at the commencement 
of thefe flues fhewn by dark fquares i in fig. 11, and marked 
ain fg. 10. The fiame divides, and a part preceeds over the 
g reverbe rated upon it y the arched roof 
drawn fro 
arge a 
mafs without peace which the beft that can be procured 
will 
