the
electrical connection leading to the magnet on the cylinder. The
cylinder is then ready to swing freely without any connections to either
oxygen pipe or electrical wires. It is then weighed, the loss in weight
being noted by removing the brass weights on the shelf attached to the
counterpoise. It is important to see that there is a sufficient number
of brass weights always on the shelf to allow for a maximum loss of
weight of oxygen from the cylinder during a given period. Since the
cylinders contain not far from 4 to 5 kilograms of oxygen, in balancing
the cylinders at the start it is customary to place at least 4 kilograms
of brass weights on the shelf and then adjust the counterpoise so as to
allow for the gradual removal of these weights as the oxygen is
withdrawn.

As soon after the beginning of the period as possible, the U-tubes are
weighed on the analytical balance, and if they have not gained too much
they are connected ready for the next analysis. If they have already
absorbed too much water or carbon dioxide, they are replaced by freshly
filled tubes.

Immediately at the end of the experimental period the barometer is
carefully set and read, and the reading is verified by another
assistant. Throughout the whole experiment an assistant counts the pulse
of the subject frequently, by means of the stethoscope, and records the
respiration rate by noting the lesser fluctuations of the tambour
pointer on the smoked paper. These observations are recorded every few
minutes in a book kept especially for this purpose.

A most excellent preservation of the record of the minor muscular
movements is obtained by dipping the smoked paper on the kymograph drum
in a solution of resin and alcohol. The lesser movements on the paper
indicate the respiration rate, but every minor muscular movement, such
as moving the arm or shifting the body in any way, is shown by a large
deflection of the pointer out of the regular zone of vibration. These
records of the minor muscular activity are of great importance in
interpreting the results of the chemical and physical determinations.

FOOTNOTES:

[5] W. O. Atwater and F. G. Benedict: A respiration calorimeter with
appliances for the direct determination of oxygen. Carnegie Institution
of Washington Publication No. 42, p. 91. (1905.)

Francis G. Benedict: The influence of inanition on metabolism. Carnegie
Institution of Washington Publication No. 77, p. 451. (1907.)

[6] W. O.