179] 



THE GOLDFISH AS A TEST ANIMAL— POWERS 



59 



24 



23 20 Minutes 



K 

 10000 



9000 



8000 



7000 



6000 



5000 



4000 



3000 



2000 



1000 







-1000 L 



-2000 



-3000 



10. 20. 30. 40. 50. 60. 70. 80. 90. lOOcc. 



Figure 26. Ethyl alcohol. Graph showing the variation of k. Abscissa represents 

 cc. of alcohol per liter and ordinate represents cc. of alcohol per liter minus the theoretical 

 threshold of toxicity concentration times survival time of the goldfish in minutes. The 

 portion AB is equivalent in range of concentration to AB of velocity of fatality curve Figure 

 17. o=2.5 cc. per liter. ^=2625. The activity of the goldfish represented by the dotted 

 line has not yet been explained. 



In Figure 24 the curve SPM= theoretical velocity of fatality curve of 

 known LiCl solution, SP'M' = unknown solution No. 1, and SP"M"=un- 

 known solution No. 2. 2.22 N. = normality of known LiCl solution. Then 

 let t)= normality of unknown solution No. 1 and m= unknown solution No. 2. 

 1 1 1 1,1,1 



2.78 * 



Then v: 2.22: u = 



= 1.95 : 2:22 : 3:91. 



OP' OP OP" 2.78 2.45 1.39 

 Thus unknown solution No. 1 = 1.95 N. and No. 2 = 3:91. 



For all methods suggested the temperature must be kept constant through- 

 out the experiment and at the same temperature as that at which the standard 

 theoretical velocity of fatality curve was prepared. These methods will not 

 hold when the temperature varies. 



