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356                                   APPENDIX X
sociate. It is likewise assumed that 90 and, 80 per cent of the
hydrogen is consumed and the oxygen remaining is combined with
the carbon and carbon monoxide. These assumptions may not be
correct, but they supply a base for the purpose desired and data
covering the case have not been found. Several other assumptions
were made and tried, but the one given seemed to average up with
the others within 4 or 5 per cent; therefore it was used. The
amount of heat released and the products of combustion were
computed in the same manner as for complete combustion,
except that the unconsumed hydrogen and carbon monoxide were
carried into the products of combustion as shown in the computa-
tions on Table 1.
Table 2 is a tabulation of the air supply and the products
of combustion for various percentages of the theoretical air
supply ranging from 60 to 500 per cent. These values are
selected with a view to facility in computation; that is, the
volume of excess air or deficiency in air, in the second and
fourth lines of the table, is the same as the volume of oxygen for
complete combustion, and the other values in this column are
simple multiples of this value. The deficiency or excess of
oxygen is one-fifth of the excess or deficiency in the air supply.
The excess of nitrogen is the difference between the excess air and
PI! '                          the excess oxygen. The total nitrogen is obtained by adding the
excess nitrogen to the volume of nitrogen in the products of com-
bustion with 100 per cent air supply. The last column, total
products of combustion, is obtained by adding the excess air to the
total volume of products of combustion with 100 per cent air
Table 3 is the computation of the points for the heat capacity
curves of the products of combustion resulting from 100-g mole-
cules of the gas. For the case in hand the computation has been
carried to ridiculous limits in order to determine the limiting
combustion conditions both with excess air and with a deficiency
of air. This point is of some importance in connection with the
use of producer and blast furnace gases, and in certain applica-
tions of these gases it has been found necessary to use an auxiliary
coal fire in order to insure ignition. It is well known that with
both of these gases the flame may be extinguished by an excess
of air cooling the products of combustion and the heating chamber
below the ignition temperature of the gases. Similar difficulties