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beat value for graphite carbon is decidedly lower
than that for tbe amorphous form of that element,
and it is probable that a part, at least, of the
carbon in coke is graphite in character. The
value, 13,(ISO B.t.u.. therefore, does not seem un­
reasonably low.
In recent literature there seems to be little which
bears upon the subject of this investigation. One
chemist, however, seems to have made some careful
inquiries along much the same lines, but unfortunately
1 have the account of bis work only in
the form of the brie! summary which appeared in
the Abstract Journal of the American Chemical
Society.© The work is a thesis by Herman Sterit.
entitled "Studies on the Chemical Comiiosition
ancl Heat of Combustion of Cokes Prepared by
Different Methods, and on tbe Determination of
the Heat of Combustion of Coals by Calculation.:
Streit's averages for beat of combustion of coke.
For oven coke 14,310 B.t.u.
For gas coke 14,400 B.t.u.
For crucible coke make by the American
method of analysis 14,580 B.t.u.
These averages are close to the commonly ac­
cepted value for carbon and much higher than tbe
one derived above from Kentucky cokes. Indeed
they seem too high.
One of the author's conclusions is that, with
few exceptions, due to abnormal composition, as
high sulphur, the heat of combustion of cokes can
be calculated within about 1 per cent, by multiplying
the per cent, of combustible matter by tbe
appropriate factor corresponding to these findings.
Thus, for an analysis by the American method, the
factor would be 145.S. Anoter conclusion is that
the heat of combustion of the
TOTAL COMBUSTIBLE .MATTEI!
of coke obtained by tbe same method from
different coals is the same, but differs if different
methods are employed. The author also concludes
that the chemical comiiosition and hence the heat
of combustion of the combustible matter of a coal
depends on the method of coking.
A paper by H. Bunte, entitled "Notes on the Byproducts
of the Gas Industry,"© an abstract of
which was seen in (he Journal of the Society of
Chemical Industry,© contains data of interest in
this connection. The author reports the chem­
ical analysis and heat of combustion of 12 gas
cokes, mostly German.
Laboratory determination of 12 gas cokes.
Ultimate analysis combustible part of cokes:
Carbon 94.18%
Hydrogen 0.90
Oxygen and nitrogen 3.77
Sulphur 1.13
99.98
THE COAL TRADE BULLETIN.
Proximate of analysis of original coal:
Total combustible matter 89.11
Water and ash 10.S9
100.00
Actual and theoretical determinations of
heat values:
B.t.u. per lb. of total combustible matter,
from tbe calorimeter determinations
i-i.ioi
Calculated from the analysis by Dulong's
method 14,006
This value, also, is higher than that obtained
from the Kentucky cokes, but tends to confirm it
because gas cokes are presumably less thoroughly
carbonized than are oven cokes and would be expected
to have a somewhat higher heat of com­
bustion on account of their containing more hy­
drocarbons.
Having decided upon a value for the heat of com­
bustion of tbe combustible matter in coke, we
may determine, by difference, what the heat of
combustion of tbe volatile combustible matter in
a coal should be, if we have
THE PROXIMATE ANALYSIS
of the coal and its heating value as determined
by tbe calorimeter.
In order to get the total combustible matter in
applying this method, I have decided to subtract
not only the ash and moisture but in addition a
further lo tier cent, of the ash, which is an allow­
ance made for the combined water contained in
the ash constituents before heating.
The ash of coals is composed largely of clay and
it is evident that this clay must have contained its
proper amount of combined water before the coal
was burned. This water would be driven off with
tbe volatile combustible matter and be counted
with it in the analysis. Kaolin contains about
13 per cent, of combined water, but as the ash
is not all clay I have assumed 10 per cent, of the
weight of the ash as approximately representing
tlie original amount of water in combination.
Accordingly, in tbe following calculations, onetenth
of the ash has been, in each case, deducted
from the amount of volatile combustible matter
shown in the analysis of the coal. The percentage
of fixed carbon multiplied by 136.8 gives the
heat of combustion of the fixed carbon. This de­
ducted from tbe heat of combustion of the original
coal gives the heat of combustion of the volatile
combustible matter, which, divided by the weight
of that matter, corrected as already explained for
combined water, gives the heat of combustion per
pound of tbe volatile combustible matter.
These calculations have been made upon the
©"riicmic.nl Abstracts," Vol. _ (1908), p. 1040.
©Herman Streit, Dissertation, 1'niv. Zurich. 1000, p.
©J. fur Gasbelencht, 40, 1807. pp. 405-407
©J. Soc. Chem. lnd., xvi (1897), pp. 661-662.