294 Investigating the Hcemolytic Activity of Chemical Substances. 



From a knowledge of these general relations, if three suitable experimental 

 readings be given for a substance, the time taken by it to produce haemolysis 

 under any circumstances of temperature or dilution may be calculated. 



As an example : — Using acetic acid (S.G. = 1'044), it is found that the 

 following Table gives the relation between certain values of T and t, when 

 8 = 1000, 



T. T. 



2 135 

 7 ■ 100 

 44-1 4 



From these values may be found, 



a = 36-4 

 /3 = 143 

 7= 40 



From the value of 7 we find first p and then c. From the values of yS and S 

 the value of 6 in the equation relating S and /3 may be found. Since c is 

 known, the value of a in this equation may be calculated, & being taken as 65. 

 When a and h are known, may be calculated and from it the value of 03. 

 This value gives the values of rn and n. Thus, we may find for acetic acid 

 that the following values are true : — 



a, h. c, m. n, p, 



5 65 20 0-0146 21-8 0-04 



The constants being known, the values of «, /S, and 7 for any dilution may be 

 calculated. For instance, when S = 1785, 



a. /3. y. 



37-8 1136 71 



The value of T corresponding to any value of r for this dilution may be found 

 in the usual way ; for example, 



S -- 1785. 



T. Texper. Tcalc. 



32 185 188-7 



While it is thus possible to calculate with considerable correctness the 

 relation of T and r for any dilution of a substance for which only three 

 experimental readings are given for one dilution, it is advisable to take three 

 readings for each of several dilutions, the accuracy of the determination of the 

 constants a, 5, c, m, n, and p being greatly increased thereby. If a sufficient 

 number of experimental readings for various dilutions are available, results 

 may be obtained graphically. 



