A small thermo-regulated water bath heater

MISSING IMAGE

Material Information

Title:
A small thermo-regulated water bath heater
Physical Description:
Mixed Material
Creator:
Davis, Loyal H
Livingstone, E. M
United States -- Bureau of Entomology and Plant Quarantine
United States -- Dept. of Agriculture
Publisher:
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine ( Washington, D.C )
Publication Date:

Record Information

Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030609812
oclc - 793358206
System ID:
AA00017469:00001


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Full Text
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ET-98 May 1937

United States Department of Agriculture
Bureau of Entomology and Plant Quarantine


A SMALL THERMO-REGULATED WATER BATH HEATER

By Loyal H. Davis, and E. M. Livingstone,
Division of Truck Crop and Garden Insect Investigations



In the course of experiments on the toxicity of hydrocyanic acid gas
to the larva of the cigarette beetle it was necessary to secure accurate control
of the temperature in the fumatoria. This was accomplished by means of a con-
stant-temperature water bath in which the fumatoria were immersed.

The heating unit herein described and illustrated does not differ in
general principle from those commonly used for maintaining a constant water-
bath temperature. It has been compactly and simply constructed, however, and
may be built economically in a field laboratory.

The apparatus is made up of a thermo-regulator. a heater-type electric
bulb, and a stirrer operated by a small electric motor. The parts were mounted
on a portable framework of wood. The thermo-regulator, purchased from a manu-
facturer of scientific instruments for $10, was easily adjusted for any desired
temperature. In order to prevent the current from arcking between its contact
points a small condenser was attached. The heater-type electric bulb was
purchased from a therapeutic supply store and cost approximately $1. A small
toy electric motor, costing $1.50, was used to operate the stirrer. This type of
irotor took up small space, produced so little vibration that the contact points
of the thermostat were not affected, and gave a long period of service. The
stirrer was made of glass tubing 8 mm. in diameter. One end was connected to the
motor drive by means of a short piece of noncollapsible rubber tubing, no
screws being used. The end of the stirrer extending into the water was sealed,
and for a distance of 11 inches from the end was flattened and bent propeller-
wise in order to produce the stirring effect. As shown in figure 1, the unit
was w-ired so that the stirrer ran continuously while the heater-type bulb op-
erated through the thermo-regulator. By the use of this apparatus a constant
temperature of 82' F. + 0.25 was maintained in a bath containing 7 gallons of
water.


'Formerly field aide.



































Digitized by the Internet Archive
in 2012 with funding from
University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan Foundation


http://archive.org/details/smallther00unit






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LIGHT BULB


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Figure 1.--IVorking diakrim of mall thermo-regulator, top and side
views, showing construction of hating unit.


Figure 2.-Outline -ketcn of thermu-regalated he&Ling unit, showing
relative size of bath, motor, stirrer, condenser, and connections.




I3 1262I 087216726


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