Thomas. — Effects of Certain Oils Upon Brook Trout 125 



As much as 265 parts : 1,000,000 of water did not affect the 

 fish in thirty-two days. 



666 parts : 1,000,000 of water showed no toxic action in ten 

 days. 



"No. 6979 is a refined coal-tar product as a residual after 

 removing some of the lower boiling distillates from crude coal tar. 

 It consists of a mixture of benzene hydrocarbons of various boiling 

 points and yields practically no distillates under 170° C. It 

 contains 14.6 per cent of organic matter insoluble in carbon 

 disulphide." 



66 parts : 1,000,000 caused death in less than twenty-four 

 hours. Upon examination, the fish killed by this tar showed con- 

 gestion of the intestines. 



13.2 parts, or less : 1,000,000 of water did not affect the fish 

 in thirteen days, after which the experiments were discontinued. 



"No. 6980 is the crude coal tar from which No. 2979 was 

 prepared. It was obtained in the manufacture of coal gas from 

 bituminous coal in Salt Lake City." 



330 parts : 1,000,000 of water caused death in seven hours'. 



100 parts : 1,000,000 of water was harmless after thirteen 

 hours of exposure of the fish to this mixture. 



"No. 7014 consists of a mixture of low-boiling distillates and 

 semi-solid asphalt obtained from Texas petroleum. It has a 

 flashpoint of 35° C, and burning point of 55° C." 



165 parts : 1,000,000 of water was harmless in thirteen days. 



"No. 7057 is an oil asphalt presumably prepared from a mix- 

 ture of Texas and Mexican crude petroleum by distilling off the 

 lighter components and possibly agitating the residue with air to 

 some extent." (This product is a solid.) 



6660 parts (by weight) : 1,000,000 of water proved non toxic. 



"No. 7819 is produced from a crude material similar to No. 

 5907 by removing some of the lower-boiling constituents. This 

 particular sample contains considerable napthalene." 



66 parts : 1,000,000 of water caused death in three days. 



33 parts : 1,000,000 of water caused death in ten days. 



A trace appeared to be non toxic. 



"No. 7058 consists of a mixture of Bermudez native asphalt 

 with some form of petroleum flux." (This product is a solid.) 



6660 parts (by weight) : 1,000,000 of water proved non toxic. 



