1911.] PUBLI(M)0(^UMENT — No. ;jl. 37 



The excelsior "vvas the or<lin:ii"y kind used for paekini!;, and 

 when boiled with creosote al)s<:)rl)ed it very readily. A coarse 

 sawdnst, princi])ally j^iiic, was used in these cxixn-inients. Ordi- 

 nary asbestos fiber was nsed, and the; oaknni came in large 

 masses, and was the same as that nsed by ]duml)ers in calking 

 joints. Cocoa fiber is a refuse product from the niaiinfactnre 

 of fiber mats, and was obtained from the Ileywood ^Fanufac- 

 turing Company. Boston. It has occasionally been recom- 

 mended for mulching plants. In all cases these fibers were 

 boiled for a long time in creosote or whatever medium was used. 

 They were then air dried before using. The excelsior before 

 being used w^as chopped up into a finer condition, so that it 

 wonld ])ack more closely in the pots. The cocoa fiber and the 

 asbestos did not take the creosote to any great extent, both being 

 practically failnres in this respect, and the oakum did not take 

 it as well as the sawdnst and the excelsior, which proved to be 

 the best in this respect. 



The results of this series of experiments in pots may be sum- 

 marized as follow^s: — 



The untreated oakum had no appreciable effect in checking 

 root development, the roots growing unharmed in the oakum 

 and j)enetrating through the bottom of the pots into the water 

 below. 



The oakum treated wuth creosote did not entirely prevent the 

 roots from passing through the oakum to the bottom of the pot. 

 Many of the roots, however, were browaied and dead where they 

 came in contact with the treated oakum. The nature of the 

 oakum was such that a less degree of compactness was main- 

 tained than in any other of the substances. 



Asbestos treated with arsenate of soda had no appreciable 

 effect, the roots penetrating the treated fibers freely, due un- 

 doubtedly to the solubilit}^ of this compound in water. 



The asbestos and creosote treatment was more effective, and 

 few if any roots extended through the pots, although there was 

 a healthy root development extending for some distance into 

 the fiber. 



Cocoa fiber treated with creosote did not prevent root devel- 

 opment to any great extent, the roots penetrating freely un- 

 harmed through the bottom of the pot. 



