VISIBLE INJURY TO VEGETATION. 



11 



etc., but enough data have been given to show the present status of 

 the case. 



EXPERIMENTS MADE IN THE BUREAU OF CHEMISTRY. 



In order that the author might be able to testify from his own 

 experience that minimum amounts of sulphur dioxid are injurious to 

 vegetation, the following experiments were made: 



A cabinet 2 by 2 feet at the base and 4 feet high was built, having 

 glass sides like a greenhouse, and so arranged that the whole top of 

 the cabinet could be lifted 

 from the wooden base to 

 allow the introduction of 

 rather large plants. (See 

 fig. 1. ) At the front a small 

 door about 1 foot square 

 was placed to allow the 

 operator to arrange the 

 plants in the cabinet and 

 introduce the vessel con- 

 taining the fluid from which 

 the sulphur dioxid was to 

 be made. The connections 

 between the top of the cabi- 

 net and the base and be- 

 tween the door and frame- 

 work of the side of the cabi- 

 net were made with rubber 

 strips and screw clamps, 

 and thus the surfaces could 

 be drawn close together and 

 the connections made as 

 nearly air-tight as possible, 

 so that practically none of 

 the sulphur dioxid could 

 escape. 



In preparation for an ex- 

 periment the plant was first 

 placed in the case and the top screwed tightly to the base. A known 

 weight of carbon disulphid in alcoholic solution held in a platinum dish 

 was then introduced into the chamber, such a weight of carbon disul- 

 phid being used that the sulphur dioxid formed by burning bore a defi- 

 nite ratio to the weight of air in the box. The alcoholic solution of car- 

 bon disulphid was then quickly lighted and the door on the front 

 adjusted. A small electric fan previously placed in the chamber was 

 then started from the outside to equalize the amount of sulphur dioxid 

 in all parts of the fumigation chamber. After the burning was com- 

 pleted the fan was stopped. In no case did the amount of alcohol 



FIG. 1 Cabinet in which plants were fumigated. 



