32 



INJURY BY SMELTER WASTES. 



INJURY TO CROPS AND SOIL BY TAILINGS AND SLAG FROM THE 

 WASHOE REDUCTION PLANT. 



The third question calling- for invest ifration was whether the water 

 from Deer Lodge Kiver, when used for irrigation piuposes, has an 

 injurious effect on the crops and the soil. It is evident from an in- 

 spection of tliis stream that tremendous quantities of waste matter 

 from the phmt find their way into it. It is also evident from the 

 method of operation that these waste products must contain some 

 copper which is, to a large extent, present as finely divided copper 

 sulphid, which is known to form soluble copper sulphate naturally 

 by gradual oxidation. It would be expected, therefore, that if this 

 material were deposited on the land it would gradually oxidize to a 

 soluble form, in which condition even very minute quantities of it 

 would be more or less injurious to vegetation. It has been urged 

 that even if soluble copper were found in the Deer Lodge River and 

 subsequently on the land it Avould be immediately rendered insolu- 

 ble again by the action of carbonates and bicarbonates present in 

 the water and soil. On the surface this seems plausible. Skinner,« 

 however, has shown that such is not the case, as when soluble copper 

 salts are brought in contact with solutions containing carbonates 

 and bicarbonates, enough copper still remains in solution to be toxic 

 to plants. 



Samples of the waste water from the plant, and samples from the 

 Deer Lodge River just below where the Avaste flows into it, and at 

 various distances farther down, were taken and the insoluble copper 

 present Avas determined with the following results: 



Table VIII. — Copper content of irrigation loater samples. 



It is evident from Table VIII that the plant discharges large 

 quantities of copper into the Deer Lodge River and that, even at a 

 distance of 16 to 18 miles below the point Avhere the tailings are dis- 

 charged, a considerable quantity of copper is still present. 



It has been proven by Heald ^ that seedlings of the ordinary garden 

 plant Pisum sativum are killed by the solution containing 1 part of 

 copper in 404,423 parts of water and that Indian corn (Zea mays) 



« Copper Salts in Irrigation Waters, J. Amer. Chem. Soc, 1906, 2S;3G1. 

 ^Bot. Gaz., 1896, 22: 125. 



