TENNESSEE SMELTERS. 13 
In a similar investigation in the vicinity of a zinc smelter at 
Lethmathe, Germany," 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, tn- 
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 was 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 35 miles north, 
9 miles south, 24 miles east, and 5 to 6 miles west, is greatly injured, 
and less severe injury extends even beyond these limits for a consid- 
erable distance (Pls. III and IV). 
TWO TENNESSEE SMELTERS. 
The next investigation of injury to vegetation by smelter fumes, 
conducted by the writer, was 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 was accompanied by one of the for- 
esters of the Department of Agriculture. Samples of soil and foli- 
age were collected for chemical examination, but the foliage came 
only from those trees which the forester was reasonably sure had not 
died from insect pests, forest fires, crowding. or other conditions 
* Haselhofft and Lindau, Die Beschiidigung der Vegetation durch Rauch. 
