12 INJURY BY SMELTER WASTES. 



(5) Pine trees fumigated 50 times with 1 part of sulphur dioxid 

 to 30,000 parts of air showed decided injury. 



Since the above work was performed in connection with the in- 

 vestigation of 1003-4, described in Bulletin 89, the writer has con- 

 ducted further experiments (during 1907) to test the effect of suljihur 

 dioxid 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- 

 l^hur 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 Avithin 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 alcohol 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 i^resent, 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 different 

 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.— Funugated 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 o«A-.— 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. 



