54 



INJURY BY SMELTER WASTES. 



Table XIII. — Sulphur triorid in foliage, in ash, and in soils around Washoe smelter- 

 nearly all samples taken from, National Forest or public domain — Continued. 



WEST OF SMELTER— Continued. 



Of 45 comparisons of injured wdth uninjured trees, in every case 

 the sulphur trioxid content of the injured tree ^vas larger than that 

 of the individual uninjured trees, and also exceeded the averages for 

 the uninjured trees of the same species situated beyond the range 

 of apparent damage. In every case also the sulphur trioxid content 

 of the ash of injured trees was greater than that of the ash of unin- 

 jured trees situated beyond the range of apparent damage, both in 

 individual cases and when average data for the uninjured trees was 

 compared with individual data for injured trees 



In a northerly direction, in 100 per cent of the cases examined, 

 both the leaves and ash of the injured trees contained a larger per- 

 centage of sulphur trioxid than the leaves and ash of uninjured trees, 

 both as regards individual and average data. 



In an easterly direction a trip was not made far enough from both 

 the Anaconda and Butte smelters to be absolutely sure that the 

 limit of injury had been reached. Hence the injured trees in an 

 easterly direction were compared with the average figures for unin- 

 jured trees of the same species taken north, south, and west of the 

 smelter beyond the range of apparent injury. In 100 per cent of 

 the cases examined both the leaves and ash of the injured trees con- 

 tained a larger per cent of sulphur trioxid than the leaves and ash 

 of the uninjured trees. This w^as true not only for the average of 

 four uninjured trees situated north, south, and w^est of the smelter, 

 but also in the individual cases. 



