367
OF ENGINEERING FORM ULÆ.
as the kaolin is volatilized by the intense heat, the caibonn
gradually burn away like an ordinary candle.
ExPEKiMtNTS with Carbons.
II
_______
II
ÄS
Best retort)
coke .. J
Carre’s carbon
Gaudoin’s „
Compressed, )
wood charcoal j"
inches.
• 35-4 X- 394
•354 diam,
•440 diaiu.
•452
inches.
2'362 I 120 11-259
ixxs. j
— ~*094 820
Fair.
2’362 120 1-25S S’2u rair.
2'716 ', 175 ,1*74'110, 820 Medium.
3'149 , 203 820 Good.
3-070 240 jl-aea-llß', 820 Very goo
Very good.
f
I
s
Carré’s carbon consist» of— Parts.
Very fine coke ground tu an impalpable powder 15
Cyleine<i lamp-black ,. .................... J*
Cementing liquid__________________ • • 5 10 7
The cementing liquid consists of 30 sugar, 12 of gum x 2
O1'rh ^carbon is moulded under pressure, then exposed in a
crucible to a cherry red for 4 or 5 hou^ nfU-rwards boiled in
a satura'ed solution of cane sugar, and after draining ?pd
wSg a-ain exposed to heat In a crucible; Gaudom s
carbon is made of tar, resin, and mineral oil cmprewH in a
lUThP Indre lamp consists of a carbon 2 millimetres
< » In base) in diameter, and 1 metre in length, contained in
» tftass rvlinder, which forms an almost ait-tight casing round
n’ it is nress'd downwards by a weieht on to a copper stud
which forms the negative contact The current pas.es to the
carbon a little way above this stua.
If precautions be taken to exclude the air, the lamp will
burn nearly 70 hours, the r te of cons’ mption for the trat
hour being about six times that of the succeeding hours.
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