a white enamel paint, which gives it a
bright appearance and makes it much more attractive to new patients. An
incandescent light placed above the head at the front illuminates the
chamber very well, and as a matter of fact the food-aperture is so
placed that one can lie on the cot and actually look outdoors through
one of the laboratory windows.

[Illustration: FIG. 26.--Cross-section of bed calorimeter, showing part
of steel construction, also copper and zinc walls, food-aperture, and
wall and air-resistance thermometers. Cross-section of opening,
cross-section of panels of insulating asbestos, and supports of
calorimeter itself are also indicated.]

Special precaution was taken with this calorimeter to make it as
comfortable and as attractive as possible to new and possibly
apprehensive patients. The painting of the walls unquestionably results
in a condensation of more or less moisture, for the paint certainly
absorbs more moisture than does the metallic surface of the copper. The
chief value of the determination of the water vaporized inside of the
chamber during an experiment lies, however, not in a study of the
vaporization of water as such, but in the fact that a certain amount of
heat is required to vaporize the water and obviously an accurate measure
of the heat production must involve a measure of the amount of water
vaporized. So far as the measurement of heat is concerned, it is
immaterial whether the water is vaporized from the lungs or skin of the
subject or the clothing, bedding, or walls of the chamber; since for
every gram of water vaporized inside of the chamber, from whatever
source, 0.586 calorie of heat must have been absorbed.

The apparatus as perfected is very sensitive. The sojourn in the chamber
is not uncomfortable; as a matter of fact, in an experiment made during
January, 1909, the subject remained inside of the chamber for 30 hours.
With male patients no difficulty is experienced in collecting the urine.
No provision is made for defecation, and hence it is our custom in long
experiments to empty the lower bowel with an enema and thus defer as
long as possible the necessity for defecation. With none of the
experiments thus far made have we experienced any difficulty in having
to remove the patient because of necessity to defecate in the cramped
quarters. It is highly probable that, with the majority of sick
patients, experiments will not extend for more than 8 or 10 hours, and
consequent