19 INJURY BY SMELTER WASTES. 
(5) Pine trees fumigated 50 times with 1 part of sulphur os 
to 30,000 parts of air Dread decided inj ury. 
Since the above work was performed in connection with the in-- 
vestigation of 1903-4, described in Bulletin 89, the writer has con- 
ducted further experiments (during 1907) to test the effect of sulphur 
cioxid on vegetation. A fumigation chamber was used consisting of 
a wooden frame 3 feet broad, 3 feet deep, and 4 feet in height, with 
glass panes, as shown in Plate II. On the side was a removable door 
which could be tightly closed. This chamber was placed over various 
trees about 3 feet in height, just as they grew in the open. The sul- 
phur dioxid was prepared by burning carbon bisulphid, in an alco- 
holic solution, in such amounts as would give definite amounts of 
sulphur dioxid in relation to the space within the chamber. A fan, 
run by dry batteries from the outside, was used.to mix the sulphur 
dioxid and the air. Each fumigation was continued for one hour, 
when the chamber was removed and the plant allowed to stand in the 
open from fifteen minutes to an hour. The chamber was entirely 
removed from the plants at night. 
Another fumigation chamber of exactly the same construction and 
size was placed over a control plant. In this chamber the same 
amount of aleohol was burned as was used in the case of those plants 
which were subjected to the action of sulphur dioxid. A fan was 
also used to mix the products of combustion of the alcohol with the 
air present, and the periods of fumigation were the same in both 
‘cases. In this way the control plants were subjected to the same con- 
ditions as the treated plants except for the presence of a definite 
quantity of sulphur dioxid. 
Following are the results obtained on fumigating several cen 
trees which were growing in their natural state in the open: 
No. 5282. Black oak.—Fumigated 4 times July 8 and 9 with sulphur dioxid 
1:1,000. After 1 fumigation the leaves were wilted and streaked. After 4 
fumigations the leaves were dry and brown. The control plant was uninjured. 
No. 5284. White oak.—Fumigated 5 times July 10 and 11 with sulphur dioxid 
1:1,000. After 3 fumigations the leaves looked gray and withered. After 5 
fumigations the leaves were gray and dry. The control plant was uninjured. 
No. 5286. Cedar.—Fumigated twice on July 13 with sulphur dioxid 1: 1,000. 
After 2 fumigations the leaves looked brown and drooped. On standing over 
July 14 the leaves appeared brown and dry. The control plant was uninjured. 
No. 5288. Chestnut.—Fumigated 5 times on July 15 with sulphur dioxid 
1:1,000. After 2 fumigations the leaves began to turn yellow. After 5 fumi- 
gations the leaves were yellow and dry. The control plant was uninjured. 
No. 5290. Black oak.—Fumigated 14 times from July 16 to July 19 with sul- 
phur dioxid 1: 10,000. After 11 fumigations the leaves were turning brown and 
new leaves and sprouts had died. After 14 fumigations all leaves were brown 
and dry. The control plant was uninjured. : 
