TENNESSEE SMELTERS. 15 



In a similar investigation in the vicinity of a zinc smelter at 

 Lethmathe, German3^« one especially conclusive examination was 

 made of the foliage of the surrounding vegetation. The investi- 

 gator, instead of selecting the trees in groups of two from the same 

 location, one injured and the other uninjured, used injured trees 

 from points near the smelter and uninjured trees for comparison 

 at points farther distant from the smelter, but in the same direction. 

 (When this can be done the results are even more conclusive than 

 those obtained by the writer by the method just outlined, but, un- 

 fortunately, the rugged nature of the country in the vicinity of the 

 smelter at Redding made such a procedure impracticable.) Of nine 

 groups of trees examined 89 per cent contained more sulphur trioxid 

 both in the leaves themselves and in the ash of the leaves of the 

 injured trees than in the uninjured ones. Three or four years later 

 the same region around the zinc smelter was again examined, and 

 it w^as found that in nineteen groups of trees the leaves of all of 

 the injured trees contained more sulphur trioxid than those of the 

 uninjured ones. 



From the work done in the vicinity of Redding, Cal., the following 

 important conclusions are drawn: 



(1) Sulphur dioxid when present in very minute amounts in the 

 air kills vegetation. 



(2) The injury is accompanied by an increased sulphur trioxid 

 content of the foliage. 



(3) The vegetation around the smelter for at least ^ miles north, 

 9 miles south, 2^ miles east, and 5 to G miles west, is greatly injured, 

 and less severe injury extends even beyond these limits for a consid- 

 erable distance (Pis. Ill and IV). 



TWO TENNESSEE SMELTERS. 



The next investigation of injury to vegetation by smelter fumes, 

 conducted by the Avriter, Avas made in 1905 and the summer of 1906 

 in the mountainous country of Tennessee, North Carolina, and Geor- 

 gia, surrounding two Tennessee smelters, and in the laboratory at 

 Washington. The following counties were examined in the various 

 trips made in the vicinity of the smelters: Polk, Tenn.; Fannin and^ 

 Gilmer, Ga., and Cherokee, N. C. Again, the only injury studied was 

 that due to the action of sulphur dioxid and trioxid on vegetation. 

 The chemist in this investigation Avas accompanied by one of the fori 

 esters of the Department of Agriculture. Samples of soil and foli- 

 age Avere collected for chemical examination, but the foliage came 

 only from those trees Avhich the forester was reasonably sure had not 

 died from insect pests, forest fires, crowding, or other conditions 



« Haselhoff and Lindau, Die BescMdiguug der Vegetation durcli Raucli. 



