22 BULLETIN 606, U. S. DEPARTMENT OF AGBICULTUEE. 



tration could be obtained at an}* of the pressures used. Creosote was 

 found chiefly in the vessels and very little in the wood prosenchyma 

 or medullary rajs. 



Elm, rock (Ulmus racemosa) — heartwood. — Rock elm is a ring- 

 porous wood with interlaced fibers. Tyloses were generally few and 

 scattered in the specimens treated. All of the specimens tested in 

 both the penetrance apparatus and in the cylinder showed erratic 

 penetrations. In most cases penetration took place in streaks, some 

 of the wood being well penetrated and other parts entirely untouched. 

 Specimens treated in the cylinder at the lower pressures showed a 

 better absorption and penetration than specimens treated at the 

 higher pressures. This may have been due to an irregular distribu- 

 tion of tyloses in the specimens. The difficulty with which this wood 

 takes treatment seems to indicate that the interlaced condition of 

 the wood fibers may vary throughout the stick, thereby causing 

 irregular penetrations. Most of the preservative was found to be in 

 the vessels. There was very slight penetration in the wood prosen- 

 chyma and medullary rays. 



Elm, slippery (Ulmus pubescens)- — heart wood. — There are practi- 

 cally no tyloses present in either sapwood or heartwood of slippery 

 elm. On account of the open condition of the large and numerous 

 pores, ife was not possible to make any tests in the penetrance ap- 

 paratus. The creosote penetrated the wood largely through the ves- 

 sels, but also to some extent in the wood prosenchyma. Good pene- 

 trations were easily secured on account of the large open pores. 



Elm, white (Ulmus americana) — heart wood. — Tyloses were few 

 and scattered in the specimens of white elm tested, and the penetra- 

 tion was chiefly in the vessels. The medullary rays and wood pro- 

 senchyma had only a slight penetration. Specimens treated in the 

 cylinder showed good penetrations with most of the pressures em- 

 ployed. Fairly good penetrations were also secured in the pene- 

 trance apparatus. 



Gum, red (Liquidambar styracifiua) — heartwood and sapwood. — 

 Eed gum is rather heavy, moderately hard, and cross-grained. The 

 fibers generally have thick walls and are arranged in definite radial 

 rows. The species is diffuse-porous with pores numerous and uni- 

 formly distributed. Tyloses are usually present and scattered in 

 both heartwood and sapwood. Infiltrating substances are present to 

 a large extent in the cell walls. It was difficult to secure an appreci- 

 able penetration of the heartwood in any of the treatments. Speci- 

 mens treated in the cylinder showed practically no radial or tangen- 

 tial penetration. The difficulty in treating this wood was very likely 

 due in a large degree to the infiltrating substances in the cell walls, 

 as well as tyloses, which prevented the preservative from entering the 

 vessels in which they were well developed. The cross-grained struc- 

 ture and thick walls of the fibers may also have been factors infiuenc- 



