THE SURFACE TENSION OF PHYSIOLOGICAL SOLUTIONS : DIFFICULTIES OF MEASUREMENT AND INTERPRETATION.

1. Data are given to show that surface tension values obtained by the ring method cannot be considered reliable when absolute values are desired. 2. Data are given to show that, in the case of solutions of semicolloids, surface tension values obtained for a definite period of time following the formation of a new interface cannot always be consistently reproduced by the ring method. 3. It is shown that in the case of solutions of semicolloids, equilibrium values are not readily obtained and should generally not be assumed to have been reached after any definite period of time. 4. The general difficulty of interpreting surface tension values obtained in the case of solutions of semicolloids, by any method, is emphasized.