A CONSTANT-TEMPERATURE BATII FOR HEATING 
BLOOD SERUM 
By R. R. Henley 
Biochemic Division , Bureau of Animal Industry , United States Department of 
Agriculture 
For heating clear anti-hog-cholera serum to a temperature of 58° to 
6o° C., as recommended by Dorset and Henley, 1 some form of constant- 
temperature bath is very desirable. Temperatures much higher than 
6o° are very injurious to serum, and on that account any form of heating 
bath should have some arrangement to prevent temperatures higher 
than 6o°; indeed, this is of almost fundamental importance in any 
automatically controlled bath. When the heating bath is kept under 
constant personal supervision the temperature is easily regulated and 
kept within the desired range, but with an automatic heater there is 
supposed to be no necessity for close personal supervision, and a derange¬ 
ment of the temperature-controlling apparatus, if unnoticed, may result 
in the complete loss of a batch of serum unless some way of preventing 
temperatures injurious to the serum has been provided. 
After considerable experimentation a bath has been devised which 
seems to embody a number of advantages. The operation of this bath 
depends upon the utilization of the vapors of a liquid having a boiling 
point at or about 61 0 C. as the heating medium, and the bath is so con¬ 
structed that a very small quantity of the liquid may be used. 
OPERATION AND DESCRIPTION OF THE BATH 
A diagram of the bath as used in the laboratory is shown in figure 1. 
In brief, the bath consists of (1) a stand, A; (2) a jacketed kettle, B, 
provided with a draw-off valve, a, for the inner kettle, an inlet, b, and 
an outlet, c, to the outer jacket; (3) a cover, C; (4) a stirrer, D; (5) a 
condenser, E; (6) a liter flask, F; and (7) a thermometer, T. A per¬ 
forated cork stopper, s , covered with tin foil, should be used to connect 
the flask, F, to the inlet of the kettle. 
In operating, the draw-off valve, o, is closed, the inner kettle, 1 5 , is 
filled with serum, the cover, C, and the stirrer, D, are adjusted and started, 
the condenser, F, is attached, and water is allowed to flow through it. 
About 300 cc. of chloroform (U. S. P., boiling point 61 0 C.) is placed in 
the flask, F, and the flask is then attached to the inlet, b , of the jacket. 
Heat, preferably a gas flame, or any other source of plentiful, controllable 
1 Dorset, M., and Henley, R. R. production op clear and sterilized anti-hog-cholera serum 
(Preliminary paper.] In Jour. Agr. Research, v. 6, no. 9, p. 333-338. 1916. 
Journal of Agricultural Research, Vol. XXI, No. 8 
Washington, D. C. July 15, 1921 
Y 111 Key No. A-59 
(54 1 ) 
