404 



crystals in the lOO mg. and 5 mg. bottles but none in the 2.5 mg. bottle. 

 The water in the bottle containing 5 mg. per liter killed fishes in a 

 somewhat longer time than the tap water solution but since the fishes 

 available were larger and many substances are commonly less toxic in 

 distilled water, the experiments were taken to indicate the approx- 

 imate toxicity given in the table. One half gram of phenanthrene and 

 one cc. of quinoline in two liters of water exposed to air proved fatal 

 a month after being placed in solution. 



Fishes are usually positive or indefinite to saturated solutions of 

 phenanthrene (Chart IV, graph 41). 



Anthracene appeared not to be toxic to fishes. 



Naphthalene. 



Ordinary tar contains 5-10%. of naphthalene. It is commonly said 

 to be insoluble, but evidently about 5 parts per million may be dis- 

 solved. The experiment of adding definite quantities to distilled water 

 was conducted in the same manner as in the case of phenanthrene ; no 

 crystals were left in the bottle with 5 milligrams per liter. 



In man it causes delirious intoxication. There are no violent 

 symptoms in fishes; they are gradually intoxicated, turn on their sides 

 and die without special symptoms or erratic movements. 



It is very much more toxic in tap water containing much carbon- 

 ate than in distilled water. Most fishes die in about half the time in 

 saturated tap water as in distilled. Fishes are usually positive to 

 naphthalene (Chart IV, graph 43, and Chart V, graph 58) but occa- 

 sionally negative (Chart IV, graph 42). 



Xylene. 



It is present in coal-tar distillates. The experiments with fishes 

 were performed in the four-liter bottle, which was laid on its side 

 after the xVlene was added and shaken until the surface film of the 

 exposed portion was free from droplets of the substance. 



It is more toxic to man than benzene or toluene. To fishes it is 

 more toxic than toluene and less toxic than benzene. Fishes are 

 gradually intoxicated in less than 50 parts per million, frequently mak- 

 ing erratic movements, jumping up in the gradient tank, etc. They 

 usually lie on their sides until death ensues. In nearly every case 

 fishes are positive to it. Two species of sunfish were positive to it 

 and remained in the stronger solution until intoxicated (Chart IV, 

 graph 44). 



