1911.] PUBLIC DOCUMENT — No. 31. 39 



length of time. For this reason it was unsatisfactory. How- 

 ever, in some experiments a large percentage of roots were 

 killed when thej came in contact with this substance, especially 

 when the creosote was retained by the fibers. 



The creosoted and untreated oakum did not prove of much 

 value. 



There was little difference between the excelsior and saw- 

 dust treatment ; one was about as good as the other, although 

 the excelsior was easier to manipulate. On the other hand, 

 the sawdust was more compact, and this was in its favor. 

 Creosote in these tests appeared to be slightly superior to Car- 

 bolineum, but the latter would be an excellent substance for this 

 purpose. 



Experiments in Boxes, 



A. — Experiments in boxes provided with vertical tile, with 

 one end plugged, have been carried on for two years. In these 

 boxes were grown tomatoes, grass and willows. The boxes 

 were 14 by 14 by 14 inches, and contained about 1 foot of 

 soil. A vertical 3-inch Akron tile extended to the bottom of 

 the boxes, the joints being 4 inches below the surface of the 

 ^oil. The bottoms of the tile were plugged with cement and the 

 tile was kept filled with water to the level of the joints. One 

 tile was placed in the middle of each of the four boxes, the joints 

 being treated with the following substances: — 



Sawdust and creosote. 

 Excelsior and creosote. 

 Cocoa fiber and creosote. 

 Oakum untreated. 



The results of this experiment are as follows : — 



The treated sawdust prevented any roots from penetrating 

 the tile, and when there was any attempt made to penetrate the 

 treated substance, the roots turned brown and died. 



The creosoted sawdust appeared as good as when first applied, 

 and was characterized by a strong creosote odor. 



The results of treatment with excelsior and creosote were 

 practically the same as those with sawdust. In a few cases, 

 however, roots forced their way along the tile to the joint. The 



