PHYSIOLOGICAL EFFECTS OF HYDROGEN CYANIDE. 375 



.6 



3 



o 



.0032 .0033 .003^ .0035.0036 



I 

 . TEMP 



FIG. 7. Curve showing the log of the rate plotted against the reciprocal 

 of the absolute temperature. Rate calculated from Fig. 5 as the time taken 

 for the intracellular cyanide to equal 25 per cent, of the external concentra- 

 tion. Calculated from the formula 



Abscissas represents reciprocal of the absolute temperature. Ordinates, the 

 log of the rate. 



RELATION OF CONCENTRATION. 



Experiments were undertaken to determine the effect of the 

 concentration of cyanide in the external solution on the penetra- 

 tion of hydrogen cyanide through frog skin. The external and 

 internal pH and the temperature were maintained constant at 6.8 

 and 25 C. respectively. The concentrations of cyanide were 

 M/I09, M/I24, M/i6o, M/i^6, M/22$ and M/^i^. The results 

 of such an experiment are plotted in Fig. 8. Each point on the 



