PHYSIOLOGICAL EFFECTS OF HYDROGEN CYANIDE. 



367 



both the " cell " and bottle fitted with rubber stoppers. The in- 

 side of the " cell " was filled with a borax-boric acid buffer solu- 

 tion and a solution of HCN in a borax buffer was placed in the 

 quinine bottle. It was necessary to use a buffer which would not 

 injure the skin or react chemically with either the cyanide or the 

 silver nitrate solution used to determine the concentration of cya- 

 nide. The pH values from 6.8 to 9.2 were obtained by changing 



H-0 



LJ 



30 



LJ 



CL 



20 







A 



10 20 30. H-0 50 

 MINUTES 



60 



FIG. i. Curve showing the relation of the position of the skin to the 

 permeability of the skin to cyanide. A, skin with the flesh side out; B, skin 

 normal, flesh side in. Abscissae, time in minutes ; ordinates per cent, cyanide. 



the relative amounts of sodium borate and boric acid ; for pH 

 values below 6.8 it was necessary to add small amounts of nitric 

 acid. The addition of HCN did not change the pH of the solu- 

 tion of either the borax or the borax plus nitric acid. Pure liquid 

 hydrogen cyanide was used. No leakage occurred around the 

 skin as shown by the fact that when a " cell " was filled with an 



