JACQUES LOEB 359 



x^ = y (y + z) 



X ■= V y {y + z) 

 / — 7 ^ 



Substituting this term '^ y \y + s) for a: in - we get 



y 



X ^ Vy {y + z) ^ -V/ J , Z 

 y y y 



The p.D. is 58 log > 1 +- = ^ log (l +-). 



y I \ y/ 



X 



In the same wav we can arrive at the term for - in the case of gelatin 



sulfate solution. If we call x the concentration of hydrogen ions in 

 the outside solution, y that of the hydrogen ion concentration in the 



X 



inside solution; then - is the concentration of the SO4 ions in the 



V 

 outside and '- the concentration of the SO4 ions of the free H2SO4 in 



the inside (gelatin) solution. The concentration of SO4 ions in combina- 



z 

 tion with gelatin becomes -. Then the equilibrium equation is as 



follows : 



y''-(y + s) 

 2 



X 



The value which interests us is ' i.e. the ratio of the hydrogen ion 

 concentration outside over that inside. 



Substituting \v- {y + s)]^ for x in - we get 



y 



X ^ -J y' (y + z) ^ aI y + z 



y y-' y 



The p. D. is therefore in the case of gelatin sulfate 



p.D. = -_ log ( 1 + - ) millivolts 



while in the case of gelatin chloride it is 



P.O. = -- log ( 1 + - ) millivolts 



