ory are
the plans for maintaining constant temperature and humidity (fig. 6).
The room is heated by five steam radiators (each with about 47 square
feet of radiating surface) placed about the outer wall, which are
controlled by two pendant thermostats. A certain amount of indirect
ventilation is provided, as indicated by the arrows on the inner wall.
The room is cooled and the humidity regulated by a system of
refrigeration installed in an adjoining room. This apparatus is of
particular interest and will be described in detail.

In the small room shown at the south side of the laboratory is placed a
powerful electric fan which draws the air from above the floor of the
calorimeter laboratory, draws it over brine coils, and sends it out into
a large duct suspended on the ceiling of the laboratory. This duct has a
number of openings, each of which can be controlled by a valve, and an
unlimited supply of cold air can be directed to any portion of the
calorimeter room at will. To provide for more continuous operation and
for more exact temperature control, a thermostat has been placed in the
duct and is so constructed as to operate some reheater coils beneath the
brine-coils in the refrigerating room. This thermostat is set at 60 deg.
F., and when the temperature of the air in the duct falls below this
point, the reheater system is automatically opened or closed. The
thermostat can be set at any point desired. Up to the present time it has
been unnecessary to utilize this special appliance, as the control by
hand regulation has been most satisfactory.

Two vertical sections through the refrigerating coils are shown in fig.
6. Section A-B shows the entrance near the floor of the calorimeter
room. The air is drawn down over the coils, passes through the blower,
and is forced back again to the top of the calorimeter room into the
large duct. If outdoor air is desired, a special duct can be connected
with the system so as to furnish outdoor air to the chamber. This has
not as yet been used. Section C-D shows the fan and gives a section
through the reheater. The brine coils, 400 meters long, are in
triplicate. If one set becomes covered with moisture and is somewhat
inefficient, this can be shut off and the other two used. When the
frozen moisture melts and drops off, the single coil can be used again.
It has been found that the system so installed is most readily
controlled.

The degree of refrigeration is varied in two ways: