405 



Tolu 



cue. 



It occurs in coal-tar and has almost the same effect upon fishes as 

 xylene, but is a little less toxic. The reactions of fishes were almost 

 invariably positive to fatal concentrations (Chart IV, graph 45; 

 Chart \^, graph 59). 



Benzene. 



Benzene occurs in coal-tar and is more toxic to fishes than either 

 toluene or xylene. In man it causes convulsions, rapid respiration, 

 coma and lowered temperature. In the case of fishes it intoxicates 

 them rapidly. These is considerable erratic movement and death en- 

 sues much as in the case of toluene or xylene. Fishes are commonly 

 negative or indifferent to benzene, their reactions to it thus differing 

 from the reactions to the other substances. They often jump out of 

 the gradient tank (Chart IV, graphs 46 and 47). 



Acetylene. 



It occurs in illuminating gas but is only slightly poisonous to man. 

 A nearly saturated solution in running water anesthetized fishes but 

 they recovered as soon as the amount was reduced. Fishes are usual- 

 ly positive to it. 



BtJiylene. 



A determination of samples of Champaign waste showed 200-300 

 cc. per liter in solution. The ethylene used was made by heating ethyl 

 alcohol and sulphuric acid and washing in alkali and water. Fishes 

 are anesthetized, lose ecjuilibrium gradually, and die without violent 

 symptoms. 



18 cc. per liter of ethylene (18 pts. per million), in running water, 

 oxygen at saturation, kills 3-4 gram orange-spotted sunfish in one 

 hour. 



30 cc. per liter (30 pts. per million), and oxygen 2.25 cc. kills 3 

 gram orange-spotted sunfish in 24 minutes; 3 grams Noiropis in 14 

 minutes ; 3 gram Pimephales in 30 minutes. 



In standing water exposed to the air in battery jars, such water 

 killed fishes as follows : 



