388 



normal fish. Thus in detailed work it is important to open and exam- 

 ine all fishes dying sooner than other fish of the same size. 



When fishes are brought into the laboratory they do not ordi- 

 narily take food and are often not well-fed or in a semi-starved state 

 when the experiments are performed. Wells found that in the case 

 of salts the resistance to adverse conditions is slightly increased by 

 starvation. To test this, fishes were kept in the aquaria from May 

 15 to Aug. 23. All died but six; those which died being their only 

 source of food. On Aug. 23 fishes recently caught were compared with 

 the starved ones. The starved fishes were from 3 to 3^ inches long 

 (7-9 cm.) and had an average weight of 7.6 gm. while fishes of this 

 length collected from the streams weighed twice as much. In the 

 fresh waste the starved fish died somewhat sooner on the average 

 though the time erf some individuals of about the same length as the 

 well-fed individuals was almost the same as the latter. In aerated 

 waste the starved fishes lived longest. On account of the small num- 

 ber (six) of starved fishes available the experiment could not be car- 

 ried out on a large enough scale to establish significant averages but 

 there was nothing to indicate that any important differences existed. 



IV. Gas-Waste — Its Character and Constituents. 



The waste of the Champaign gas plant consists of what is known 

 as the "drip", which accumulates in the bottom of the holders and in 

 the pipes leading to and from them, also in the mains throughout the 

 town. It consists of water with illuminating gases and other coal 

 products in solution. On the surface of this water a light tar floats, 

 while some heavy tar may rest at -the bottom. 



The waste is pumped from the inlet and outlet of the holder onto 

 the ground beside the tank, and is alleged to flow into the Boneyard 

 Creek in wet weather. The light tar is used by the gas-works people 

 for paint, for which purpose it appears to have some value. It dries 

 hard and rather quickly. The heavy tar is removed but as is the usual 

 case with small plants, everything else is thrown away. 



Coal-tar is an excessively complex mixture of chemical compounds 

 many of which occur in its distillation between naphthalene on the 

 one hand and anthracene on the other. It contains nitrogenous com- 

 pounds, chiefly of a basic nature. The usual constituents of the waste 

 and tar varies with the coal used, the temperature and the method of 

 washing and testing the gases etc. during the process of manufacture 

 and the amount of water gas added. 



These constituents may be classified and described as follows 

 (Lunge '00). 



