INJURY TO VEGETATION BY SMELTER FUMES. 



TABLE 7. Comparison of the sulphur trioxid content of eastern and western 



pines and of their soils. 



EASTERN PINES (UNITED STATES DEPARTMENT OF AGRICULTURE GROUNDS) 

 NOT EXPOSED TO SMELTER FUMES. 



WESTERN PINES FROM COUNTRY SURROUNDING SMELTER, REDDING, CAL. 



In Table 8 the same figures are given as in Table 4, but they have 

 been arranged in groups, according to the direction from the smelter, 

 i. e. , all trees in a northerty direction are in one group, all trees in a 

 southerly direction in one group, etc. It will be noted that north of 

 the smelter, in 100 per cent or all of the groups examined the injured 

 trees contain more sulphur trioxid, both in the dried leaves and in 

 the ash, than the uninjured trees. South of the smelter, in 86 per 

 cent of the groups examined the injured trees contain more sulphur 

 trioxid than the uninjured, and in 71 per cent of the groups exam- 



