coal trade bulletin - Clpdigital.org

38 THE COAL TRADE BULLETIN.
Total volume for combustion 106.75
Volume after burning 83.20
Contraction due to burning 23.55
Volume after absorption of CO, 71.40
CO, produced by combustion 11.80
The record of a typical analysis by (be explo­
sion method follows. The analysis is hypothet­
ical and is presented simply to show the errors in­
troduced by* small variations in burette readings.
C. c.
Volume taken for analysis 100.00
Volume after absorption of CO. 92.92
CO, found 7.07
Volume after absorption of O. 91.73
O. found 1.20
Volume taken for explosion 31.77
O. added for explosion 68.23
Total 100.00
Volume after explosion 84.00
Contraction due to explosion 16.00
Volume after absorption of CO, 76.00
CO. produced by combustion 8.00
In the last analysis an experimental en or of
0.2 c. c. in reading the gas volume after com­
bustion would make this reading S3.S c. c. An
experimental error of 0.2 c. c. in reading the gas
volume after the final carbon dioxide absorption
would make the reading 76.2. The contraction
due to combustion would then become 16.2 c. c,
and the volume of carbon dioxide would become
7.6 e. c. Hydrogen and methane, if calculated
from these data aid figured to a percentage basis,
would be:
Per cent.
H. 1.93
CH, 21.94
It will be seen that if only a part of the resi­
dual gas is taken for the analysis and if an error
of 0.2 per cent, is made in two burette readings,
then the calculation will indicate considerable
hydrogen.
An experimental error of plus 0.2 c. c. made in
reading the gas volume after combustion would
result in an apparent reading of 84.2 c. c. An
experimental error of 0.2 c. c. made in reading
the gas volume after the carbon dioxide absorp­
tion would result in an apparent reading" of 75.8.
The contraction in volume and carbon dioxide
produced by* the explosion then become 15.S c, c.
and 8.4 c. c. respectively, and if tbe calculation
is made to methane and ethane the results be­
come 20.38 per cent. CH, and 1.94 per cent. C,H„.
KRHORK nil*. TO THE ASSUMPTION THAT THE MOLECU­
LAR VOI.I .MI'S OF ALL CASKS ARE ALIKE.
Exact specific gravity determinations have
shown that tbe molecular volumes of all gases
are not alike, and as a consequence some gas
analyses may be in error if Avogadro's theory be
assumed.
Beloyv are given the theoretical and observed
specific- gravity determinations (air=l) at 0° C.
and at 760 mm. pressure of those gases that enter
into reaction when methane is burned in com­
plete combustion yvith oxygen.
Comparison of theoretical and observed specific-
gravity determinations.
Theoretical Observed
Gas. density. density.
Oxygen 1.1055 1.1053
Nitrogen 9680 .9674
Methane 5539 .5545
Carbon dioxide 1.5201 1.5291
Theoretical
Observer. Observed.
Rayleigh 1.000
do 1.000
Baume and Perrot 999
Rayleigh 994
The molecular volumes of oxygen, nitrogen and
methane are close enough to the theoretical, hut
considerable variation is noted in tbe theoretical
and observed molecular volumes of carbon dioxide.
Tbe weight of a liter of carbon dioxide at 0° C.
and 760 mm. pressure is 1.9769 grams according
to Rayleigh© and 1.976S grams according to Guyc
and Pintza.©
Then 22.412 liters of carbon dioxide weighs
22.412 X 1.9768 - 44.304 grams at 0' C. and 760
mm. pressure. The coefficient of expansion of
carbon dioxide betyveen 0° and 20", as determined
by Chappius.® is 0.003736.
Then 22.412 X0.003736 X 20 = 1.6746 liters;
1.6746 4- 22.412 = 24.087 liters, the volume occu­
pied by 44.304 grams of carbon dioxide when the
temperature has been raised to 20° C. from 0° C.
at 760 mm. pressure. A gram-molecule of carbon
dioxide equals 44.003 grams and occupies at 0° C.
and 760 mm. pressure:
44.003
44.305
X 24.0S7 -- 23.923 liters.
According to the gas layvs, at 20° C. and 760 mm.
pressure the volume becomes
293
22.412 x 24.051 liters.
273
At 20 C. and 760 mm. pressure then a gram-
molecule of carbon dioxide occupies a volume
(CONTINUED ON PAGE 43)
©Rayleigh. flu the deiisiiies of carbonic oxide, carbonic
anhydride, and nitrous oxide. Proc Roy Snivel.
6*2. 1897, 1). 204.
©Guye, I'. A., and I'intza. A.. Determination des densites
des gaz anhydride carbonique, ammofiJae et protoxyde
d'azote. Mem. Sec. pfiys. el hist, nat de
Geneve, vol. 35, 1908, p. 569.
©Bull. Inst. poids. pt mes.. vol. 13, 190:',, p. mo.