Consequently at present no correction for interchange of air in the
food-aperture is made, and for the same reason the slight alteration in
volume resulting from the removal or addition of material has also not
been considered here.

USE OF THE RESIDUAL BLANK IN THE CALCULATIONS.

To facilitate the calculations and for the sake of uniformity in
expressing the results, a special form of blank is used which permits
the recording of the principal data regarding the analyses of air in the
chamber at the end of each period. Thus at the head of the sheet are
recorded the time, the number of the period, kind of experiment, the
name or initials of the subject, and the statement as to which
calorimeter is used. The barometer recorded in millimeters is indicated
in the column at the left and immediately below the heading, together
with the temperature of the calorimeter as expressed in degrees
centigrade. The temperature of the calorimeter as recorded by the
physical observer is usually expressed in the arbitrary scale of the
Wheatstone bridge and must be transposed into the centigrade scale by
means of a calibration table.

The apparent air-volumes in the subsections of the ventilating system
are recorded under the headings I, which represents the volume of air
containing water-vapor and therefore is the air in the chamber plus the
air in the piping to the surface of the acid in the first sulphuric-acid
absorber; I-II, which represents the air containing carbonic acid and
includes volume I plus the volume of the air in the first sulphuric-acid
vessel and the volume of air in the potash-lime absorber; I-III, which
includes the total confined volume of the whole system, since this air
contains both oxygen and nitrogen. These volumes change somewhat,
depending upon the size of the body of the subject, the volume of the
materials taken into the chamber, and the type of calorimeter.

The data for the residual analyses are recorded in the lower left-hand
corner: first the weight of the water absorbed from 10 liters of air
passing through the meter; to the logarithm of this is added the
logarithm of volume I; the result is the logarithm of the total weight
of water-vapor in the ventilating air-current. To convert this into
liters the logarithmic factor 09462[26] is added to the logarithm of the
weight of water and (_a_) is the logarithm of water expressed in liters.
A similar treatment is accorded the weight of carbon dioxide ab