CHARACTER OF WASTES. 9 



(2) In case arsenic is present in the ores, as it often is and notably 

 c inaconda, it is given off in the fumes from the smelter in volatile 

 form and deposited on the surrounding land and crops, where it may 

 be present in sufficient amounts to jDoison cattle browsing on exposed 

 ranges, or living on hay cut from such pasture. 



(3) The tailings from the water concentration of the ore and the 

 slag, in a finely divided condition, are discharged on a dump heap 

 through which the water from the plant is constantly percolating on 

 its course to adjacent streams and the " slimes " are left in piles in 

 the open air. Both the slime heap and the dump are also exposed to 

 the percolating action of the rain. In consequence, the streams re- 

 ceiving the waste water from concentrating and smelting plants con- 

 tain a comparatively large amount of copper in suspension and are 

 apt to hold some copper in solution. If these streams are used for 

 irrigating purposes there is a possible source of injury to growing 

 crops due to the action of the copper present. 



(4) Finely divided particles of the ore are discharged from the 

 smelter stack and settle on the surrounding country. These fine par- 

 ticles of flue dust may contain sufficient amounts of copper, lead, and 

 zinc to injure vegetation, because of their toxic action through the 

 medium of the soil and because of their caustic action on the f ;)liage. 

 While it is believed by some '^ that the action of this so-crJled flue 

 dust gives rise to the principal damage caused by smelter smoke, the 

 writer is inclined to the opinion ^ that such injury is not of great sig- 

 nificance except in a very limited area about the smelter, and that an 

 investigation of it is in most cases unnecessary, as the owners of smelt- 

 ers are usually perfectly willing to admit damage, even beyond the 

 area likely to be affected by the solid particles of copper, lead, and 

 zinc in the flue dust. 



In the first case of this kind studied by the writer in the vicinity 

 of Redding, Cal. (see PL I), and in the laboratory at Washington 

 during 1903 and 1904, no complaint had been made of the injury 

 from arsenic or from copper, so that the only problem considered 

 was the action of sulphur dioxid and trioxid fumes on the surround- 

 ing vegetation. The results of this study and the original investiga- 

 tions connected therewith have been published,^ but a resume will be 

 given, together with certain results obtained since the publication 

 of the Redding investigations, in order that the reader may under- 

 stand the present status of the work. 



«Ebaiigh, J. Amer. Chem. Soc, 1907, 29: 951. 

 ^ Haywood, Science, 1907, 26: 476. 



^U. S. Dept. Agr., Bureau of Chemistry, Bui. 89, Injury to Vegetation by 

 Smelter Fumes, 1905. 



38816— Bull. 113—10 2 



