INJURY, RECOVERY, AND DEATH 



ing 55, which is the amount of growth in the pure solutions, 

 and in this case (since all the pure solutions are equally 

 toxic) the amount of growth which would occur if the toxic 



actions of the salts were 

 additive (that is, if each 

 salt exerted its own toxic 

 effect independently of the 

 other salts) ; the result 

 should then be divided 

 by 55. 



In this case the addi- 

 tive effect is represented 

 by a plane surface parallel 

 to the plane which forms 

 the base of the model. The 

 height of this plane is 

 indicated by the shading 

 in the figure. 



Other methods (as 

 mixing unequally toxic 

 solutions or keeping the 

 concentration of one salt 

 Ca constant while varying 



that of the others) will 



ofNaCl0.12Af,|KCl0.13^,andCaCh0.164M. 



effect a curved surface very difficult to determine and 

 not easily represented or measured on the model. 



With solutions of more than three components the 

 results cannot be expressed in a solid model; but a 

 graphical expression may easily be obtained in the follow- 

 ing way. Let us suppose that equally toxic solutions 

 of A, B, C and D are to be mixed. A mixture of the first 



