SURFACE TENSION OF SERUM : VI. THE STUDY OF IMMUNE SERUM. TIME-DROP AND INITIAL VALUE OF SURFACE TENSION.

1. The initial surface tension of serum or serum solutions is not affected systematically by the presence of antibodies in the serum. On the contrary, the time-drop in 2 hours is always increased, from 25 to 100 per cent. 2. It is extremely important, in order to demonstrate these phenomena, that the greatest care be taken regarding the cleanness of the vessels and the purity of water and NaCl. 3. It is equally important to use a device, for example such as is pictured in this paper, capable of preventing the jarring and shaking of the liquid. 4. The value of the time-drop of a normal, healthy serum is never higher than 10 dynes. Should it be higher, the serum must not be used for immunity experiments.