174 



LECTURES ON IMMUNITY 



addition of a strong acid to a solution of ammonia. The 

 line AB then deviates a little more, but not very much, 

 from a straight line, according to the relatively strong in- 

 fluence of the ammonium salts. The real curve would lie 

 little below AB. 



FIG. 2. 



Now, if we add to the ammonia-solution a very weak 

 acid, such as boracic acid, which has no sensible haemo- 

 lytic action, the phenomenon will behave in a rather differ- 

 ent manner, in consequence of the hydrolytic effect of the 

 water. The hydrolysis results in this, that there always re- 

 mains a certain quantity of free ammonia, even if we add 

 as large quantities of boracic acid as possible (up to satu- 

 ration). Then the curve representing the toxicity de- 

 scends as the quantity of boracic acid added increases, but 

 never reaches zero, as is indicated on Fig. 2. The 

 quantity (q) of free ammonia may be calculated according 

 to the equation : 



