value of M, which is not
necessarily a whole number, should be determined for each test, though
in all probability such a value is a constant for any individual
calorimeter which is properly operated.

The correction for radiation as found on page 188 is in all instances to
be added to the range of temperature between the firing point and the
point chosen from which the final radiation is calculated. This
corrected range multiplied by the water equivalent of the calorimeter
gives the heat of combustion in calories of the coal burned in the
calorimeter together with that evolved by the burning of the fuse wire.
The heat evolved by the burning of the fuse wire is found from the
determination of the actual weight of wire burned and the heat of
combustion of one milligram of the wire (1.7 calories), _i. e._,
multiply the weight of wire used by 1.7, the result being in gram
calories or the heat required to raise one gram of water one degree
centigrade.

Other small corrections to be made are those for the formation of nitric
acid and for the combustion of sulphur to sulphuric acid instead of
sulphur dioxide, due to the more complete combustion in the presence of
oxygen than would be possible in the atmosphere.

To make these corrections the bomb of the calorimeter is carefully
washed out with water after each test and the amount of acid determined
from titrating this water with a standard solution of ammonia or of
caustic soda, all of the acid being assumed to be nitric acid. Each
cubic centimeter of the ammonia titrating solution used is equivalent to
a correction of 2.65 calories.

As part of acidity is due to the formation of sulphuric acid, a further
correction is necessary. In burning sulphuric acid the heat evolved per
gram of sulphur is 2230 calories in excess of the heat which would be
evolved if the sulphur burned to sulphur dioxide, or 22.3 calories for
each per cent of sulphur in the coal. One cubic centimeter of the
ammonia solution is equivalent to 0.00286 grams of sulphur as sulphuric
acid, or to 0.286 x 22.3 = 6.38 calories. It is evident therefore that
after multiplying the number of cubic centimeters used in titrating by
the heat factor for nitric acid (2.65) a further correction of
6.38 - 2.65 = 3.73 is necessary for each cubic centimeter used in
titrating sulphuric instead of nitric acid. This correction will be
3.73/0.297 = 13 units for each 0.01 gram of sulphur in the coal.

The total correction t