guished (on standing the color reappeared). 13.40 ml. thiosulfate (theory = 13.29 ml.).
The activitv oarameter was determined as
The blanks required follows. A 5-ml. portion of the friction was diluted to 60 ml., and a 0.1-ml. dose was given intraperitoneally twice daily for 10 days to eight mice starting 20 hr. after inoculation of 5 X los Ehrlich ascites tumor cells. At 30 dais. the number of ascitic (abdominal dstension) and nonascitic wrvivors was counted. The activity parameter is the sum of the nonascitic survivors and one-half the ascitic survivors out of the group of eight mice used for each bioassay. Only tubes 5-10 had any survivors at 30 days. The bioassays gave the results shown in Table V. The data on all of the parameters obtained are plotted in Fig. 2.
REFERENCES
( I ) F. L. Tabrah, M. Kashiwagi, and T. R. Norton, Science, 170, Nonsink Dissolution Rate Equation PAKDEE POTHISIRI and J. THURP CARSTENSENA Ahstract An equation was developed which describes thc dissolution of monodibperse particles beyond the point where concentrations are small compared to solubility. I f it is assumed that a stagnant layer model applies. the thickness of these layers is of the same order of magnitude as calculated rirr the Hixson-Crowell treatment b u t dissolution rate constants are 1.5-2 times as large. The application of the equation to dissolution of hydrocortisone, levodopa, and p-hydroxybcnzoic acid i5 shown. Kegphrases C Dissolution rates, monodisperse particles-equation developed for nonsink conditions, applied to hydrocortisone, levodopa. and p-hydroxylwnzoic acid C Particles, rnonodispersenonsink dissolution rate equation developed. applied to hydrocortisone, levodopa, and p-hydroxybenzoic acid ( 1897).