CAN 
than one-fifth or one-fixth, before the uneafinefs of the 
eye induces us to fmifF it. Hence, if candles could be made 
. fo as not require fnuffing, the average quantity of light af¬ 
forded by the fame quantity of combuftibl'e matter would- 
be more than doubled. On this interefting fubjeCf, the 
following ingeniou's obfervations have been publifhed by 
Mr. Nichollan, in his valuable Journal of. the Arts, as 
follows: 
“ In every procefs of combuftion, the free accefs of air 
is of the utmoft confequence. When a candle has a-very, 
(lender wick, the flame is final 1 and of a brilliant white 
colour ; if the wick be large, the combuftion is let's per- 
feil, and the flame brown; and a wick (till larger,, not 
only exhibits a brown flame, but the lower internal part 
appears dark, and is occupied by a portion of volatilized 
matter, which does not become ignited till it has afcended 
towards the point. When the wick is either very large 
or very long, part of this matter efcapes combuftion,. and 
(hews itfelf in the form of coal or fmoke. The fame things 
take place in the burning of a lamp ; but, when the wick 
of a lamp is once adjufted as to its length, the flame con¬ 
tinues nearly in the fame date for a much longer time than 
the flame of a candle. Upon comparing a candle with a 
lamp, two very remarkable particulars ar.e feen. In the 
firft place, the tallow itfelf, which remains in the unfit fed 
ilate, affords a cup or cavity to hold that portion of melt¬ 
ed tallow which is ready to flow into the lighted part of 
the wick. In the fecond place, the combufton, inftead of 
being confined, as in the lamp, to a certain determinate 
portion of the fibrous matter, is carried, by a flow fuccefl¬ 
it on, through the whole length. Hence arifes the greater 
neceflity for frequent fnuffing the candle; and hence alio 
the ftation of the freezing point of the fat oil becomes of 
great confequence.. For it has been ffiewn,. that the bril¬ 
liancy of the flame depends very much on the diameter of 
the wick being as final 1 as poilible ; and this requifite will 
be ntoft attainable in candles formed of a material that re¬ 
quires a higher degree of heat to fufe it. The wick of a 
tallow-candle muff be made thicker, in proportion, to the 
greater fuiibility of the material, which would other-wife 
melt the Aides of the cup,, and run over in dreams. The 
flame will therefore be yellow, fmoky, and obfcure, ex¬ 
cepting for a fliort time immediately after fnuffing. Tal¬ 
low melts at the 93d degree of Fahrenheit’s thermometer ; 
fpermaceti at the 133d degree ; the fatty matter formed of 
flefh, after, long immerfion in water, melts at 127 degrees; 
the pda of the Chinefe at 145 degrees; bees-wax at 142. 
degrees; and bleached wax at 155 degrees. Two of thefe 
materials are well known in the fabrication of candles. 
Wax in particular does not afford fo brilliant a flame as 
tallow ; but, on account of its lefs fufibility, the wick can 
be made fmaller, which not only affords the advantage of 
a clear perfect Same, but from its flexibility it i3 difpofed 
to turn on one fide, and come in ccntaft with the external 
air, which completely burns the extremity, of the wick to 
white aflies, and thus performs the office, of (buffing. We • 
fee therefore, that the important object to fo.cie.ty, of ren- ‘ 
dering tallow candles equal to thofe of wax', does not at all 
depend on the combuftibiiity of the refpeCtive materials,, 
but upon a mechanical advantage in the cup, which is af¬ 
forded by the inferior degree of fufibility in the wax ; and 
that,.to obtain this valuable objeCt, one of the following, 
effects mutt be produced : either the tallow muff be burn¬ 
ed in a lamp,, to avoid the gradual progreltion of the flame . 
along the wick ; or fome means mu fir be deviled to enable- 
the candle to (huff itfelf, as the wax-candle-does; or, lad- 
]y, the tallow itfelf mull be. rendered lefs fufible by- fonts, 
chemical prccefs. 
“-The makers of thermometers-and other articles with, 
the blow-pipe and lamp, give the preference to tallow in- 
flead of oil, becaufe its combuftion is more-complete, and 
does not blacken the glafs. In this operation, the heat of 
the lamp melts the tallow which is oceafionally brought 
into its vicinity, by the workman. But, for-the-ufual pur- 
pofes of iiluminationy.it ran'not be fuppofed that a perfoti 
D L E. jn 
can attend to fupply the combufiible matter. Confidera- 
ble difficulties a rife in the project for affording this gra¬ 
dual fupply as it may be.wanted. A cylindrical piece of 
tallow was inferted into a metallic tube, the upper aper¬ 
ture of which was partly doled by a ring, and the central 
part occupied by a metallic piece nearly refembling that 
part of the common lamp which carries the wick. In this 
apparatus the piece laft deferibed was intended to anfwer 
the fame purpofe, and was provided with a fliort wick. 
The cylinder of tallow was fupported beneath in fuch a 
manner that the metallic tube and other part of this lamp 
were left to reft with their whole weight upon the tallow 
at the ring or ccntraclion of the upper aperture-. In this 
fituation the lamp was lighted. It burned for fome time 
with a very bright clear flame, which, when compared 
with that of a candle,, pofletted the advantage of uniform 
intenfity,- and was much fuperior to the ordinary flame of 
a lamp in its colour, and the perfect abfence of fmell. Af¬ 
ter fome minutes it began to decay, and very foon after¬ 
wards went out. Upon examination, it was found that the 
metallic piece which carried the wick had fufed a fuffici- 
ent quantity of tallow for the fupply during the combuf¬ 
tion ; that part of this tallow' had flowed beneath the ring, 
and to other remote parts of the apparatus, beyond the in¬ 
fluence of the flame; in.confequence of which, the tube 
and the cylinder of tallow were fattened together, anil the 
expended- progrefflon of fupply prevented. It feems-pro¬ 
bable, that in every lamp for burning confident oils, the 
material ought to be fo difpofed that it may defeend to the 
flame upon the principle of the fountain refervoir. I (hall 
net here date the obttacles which prefent themfelves in tlie 
profpeft of this conftruttion, but (hall difmifs the fubjedt 
by remarking, that a contrivance of this nature would be 
of the greateft. public utility. 
“ The wick of a candle, being furrounded by the flame, 
is nearly in the fit-nation of a body expofed to deftrudtive 
dittillation in a ciofe velfel. After lofing its volatile pro¬ 
ducts,. the carbonaceous red due retains its figure, until, 
by the defcent of the flame, the external air can have ac¬ 
cefs to its upper extremity. But, in this cafe, the requi- 
(ite combuftion, which might fiiuff it, is not effected : for 
the portion of oil emitted by the long wick is not only too 
large to be perfectly burned, but alfo carries off-much of 
the heat of the flame while it affinities the elaftic ffateu By 
this diminifhed combuftion and increafed efflux, of half-de- 
compofed oil, a portion of coal or foot is deposited on the 
upper part of the wick, which gradually accumulates, and 
at length affumes the appearance of a fungus. The candle 
does not then give more than one-tenth of the light emit¬ 
ted in its bed: (late. Hence it is-that a candle of tallow- 
cannot-fponfaneoufly fnuff itfelf. It was not probable that 
the addition of a fubflance, containing vital air or oxygei^e, 
would fupply that principle at the precife period of. tiufe 
required ; but,.as experiment* is the teft-of every probabi¬ 
lity of this nature, I (baked a wick of cotton in a folution 
Of nitre, then dried it, and made a candle. When this, 
came to be lighted^ nothing remarkable happened fora 
fhort time ; at the expiration of which a decrepitation fol¬ 
lowed at the lower extremity of the flame, which com- - 
pletely. divided the wick where the blackened part com¬ 
mences. The whole of the matter in combuftion there¬ 
fore fell off, and the candle was of courfe in-da at ly extin¬ 
guished, Whether this would have happened in all pro¬ 
portions of the (alt, or conftruttion of the candle, (did. 
wot try, becaufe the fmell of azote was fufficientl.y ftrong 
and unpleafant to forbid the ufe of nitre’ in the purfuit. 
From various confide rat ions. I am difpofed to think that 
the fpontaneous fnuffing of candles, made of tallow, or 
other fufible-materials, will fcarcely be effected but by the 
difeovery of fome material for the wick which (hall be vo¬ 
luminous enough to abforb the -tallow, and at the fame 
time fuificiently flexible to bend on one. fide. 
“ The mod p.romifing fpeculation refpefting this mod 
ufeful article, feems to diredl itfelf to the cup. which con¬ 
tains the melted, tallow. The imperfection of this part 
, he&,. 
