120 



CHEMICAL EQUILIBRIA 



TOXICITY q OF 0-04 cc. TETANOLYSIN AFTER ADDITION 

 OF n cc. (^ EQUIVALENTS) OF ANTILYSIN (MADSEN) 



K = 0-115 at 37 C. 



It is quite clear that it is impossible to determine 

 the quantity of antidiphtheric serum which is equiva- 

 lent to a given quantity of diphtheria poison by 

 looking for how much serum must be added to the 

 said quantity of poison in order that the mixture 

 shall be innocuous, as is usually done. In medical 

 practice it is of course necessary to give a moderate 

 excess of antiserum in order to be certain of the 

 innocuity. Even if we mix the double equivalent 

 quantity of antidiphtheric serum with 100 lethal doses 

 of diphtheria poison, still 9 lethal doses are free, and 

 with the five-fold quantity of antitoxin (in equiva- 

 lents) 2-7 lethal doses are not bound. The only 



