Investigation of the freezing point of the blood serum in infants has been greatly restricted owing to the necessity of using, with the ordinary Beckmann thermometer, relatively large quantities of fluid, from 10 to 20 cc. Although the Beckmann apparatus has been modified by Guye and Bogden,1 Burian and Drucker2 and others for use with small quantities of fluid, we have not been able to obtain consistent results with any of the modified Beckmann thermometers that we have been able to obtain. In 1911, Salge3 used a thermocouple to determine the freezing point of blood serum of children, and recently Bishop4 described a method involving the use of a potentiometer by which the freezing point of as little as 0.2 cc. of fluid can be determined.
The method here described is the one used by us in making determinations of the freezing point of blood serum