20 INJURY BY SMELTER WASTES. 



In this table, with possibly two or three exceptions, it will be 

 noted that the soils close to the smelters contain very nearly the 

 same amounts of sulphur trioxid as those farther away, so that in 

 comparing injured trees situated near the smelter with uninjured 

 trees at a greater distance the soils in which they grew may be con- 

 sidered identical. 



Out of 49 such comparisons it will be noted that 46 times, or in 

 94 i^er cent of the cases examined, the sulphur trioxid content of the 

 injured trees is larger than that of the uninjured trees of the same 

 species situated beyond the range of the seemingly significant dam- 

 age and that in 40 cases, or 82 per cent of the number examined, the 

 sulphur trioxid content of the ash of such injured trees is larger 

 than that of similar uninjured trees situated be3^ond the range of 

 aj^parent damage. 



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

 leaves of the injured trees contain a larger percentage of sulj^hur 

 trioxid than the leaves of the uninjured trees and in 81 per cent of 

 the examinations the ash of such injured trees contains a larger per- 

 centage of sulphur trioxid than the ash of the uninjured trees. 



In an easterly direction in 100 2)er cent of the cases examined the 

 leaves of the injured trees contain a larger percentage of sulphur 

 trioxid than those of the uninjured trees and in 75 per cent of the 

 cases examined the ash of such injured trees contains a larger per- 

 centage of sulphur trioxid than the ash of those uninjured. 



In a southerly direction in 77 per cent of the cases examined the 

 leaves of the injured trees contain a larger percentage of sulphur 

 trioxid than the leaves of the uninjured trees and in 69 per cent of 

 the examinations the ash of such injured trees contains a larger per- 

 centage of sulphur trioxid than the ash of those uninjured. 



In a southerly direction, if only those trees are considered which 

 were within a distance of 6J miles from the smelters, it appears that 

 in 88 per cent of the cases examined the leaves of the injured trees 

 contain a larger percentage of sulphur trioxid than those of the 

 uninjured trees and in 100 per cent of the examinations the ash of 

 such injured trees contains a larger percentage of sulphur trioxid 

 than the ash of those that are uninjured. 



In a westerly direction in 100 per cent of the examinations both 

 the leaves and the ash of the injured trees show a larger content of 

 sulphur trioxid than do the leaves and the ash of the uninjured trees. 



From this investigation the following conclusions are drawn in 

 regard to the distribution of the injury by smelter fumes: 



(1) The vegetation around the smelters appears from actual chem- 

 ical analysis to be injured for at least 12 to 12 J miles north of the 

 smelters, 6J miles south, 5J to 6 miles east, and 9J miles west. 



