temperature of the room may have upon the water in the cylinder during
the time occupied by the first half of the experiment, would be
compensated for by the loss sustained during the second half of the
experiment, when the temperature of the water exceeded that of the room.
The mean of numerous trials gave 13.4 deg. F. rise of temperature, equal to
14.74 lb. of water per lb. of coal. When the water was at 50 deg. and
the room at 57 deg., the mean of several experiments gave 13.5 deg. rise of
temperature. When the water was 40 deg. at starting and the room at 47 deg.,
13.65 deg. was the average rise of temperature. Trials were made at
intermediate temperatures, and the results always showed that higher
figures were recorded when the water was coldest. With a view of getting
uniformity in the results it was thought well to make experiments, in
order to find out what temperature the room should be at, so that this
coal might give the same result with the water at 50 deg., 40 deg., or at
intermediate temperatures. Without going much into detail, it was found
that when the temperature of the room was at 40 deg. and that of the water
40 deg., and the experiment was rapidly and carefully performed, 13.4 deg. rise
of temperature was given; but this result could be obtained without
special effort when the room was 42 deg. and the water 40 deg. at starting. It
is evident that the cooling effect of the air in the room upon the water
cylinder is very appreciable when the water has reached 13 deg. above that
of the room. When the water was at 50 deg. and the room at 55 deg., the coal
gave 13.4 deg. rise with ease and certainty, and it would not be out of
place to remark here that with those coals which burn well in Thompson's
calorimeter, the results of several trials are remarkably uniform when
properly performed. With the water at 70 deg. and the room at 80 deg., a like
result was worked out. Experiments at intermediate temperatures were
also carried out (see table in sequel). It is true that the whole
difference of temperature we are dealing with in making these
corrections is only 0.25, but 0.2 in the result, when multiplied by 537