CURRENT LITERATURE. 

 Henry S. Graves, In Charge. 



Experiments on the Strength of Treated Timber by W. K. Hatt, 

 Circular No. 39, U. S. Forest Service, Washington, 19O6. 



A concise summary of over 6,000 tests of the strengtl] of treated 

 and natural wood, made at the St. Louis Exposition during 1901. 



A small timber preserving plant and testing labratory was erect- 

 ed by the Forest Service upon the Exposition grounds, in the "Min- 

 ing Gulch," and treating and strength tests carried out according to 

 plans drawn up by Dr. H. von Schrenk and Dr. W. K. Hatt. The 

 treating cjdinder and plant and the material for the experiments, 

 which was in the form of railway ties, chiefly loblolly pine, were 

 supplied gratis by parties interested. 



The object of the tests Avas to determine the effect upon the 

 strength produced by the processes of treatment; namely, steaming 

 for various lengths of time under different pressures; impregnation 

 of zinc chlorid solutions, commercially known as the "Burnettizing 

 Process," and impregnation of creosote by means of pressure and 

 vacuum. 



The plan was to saw the ties into two portions, from which the 

 specimens 2x2 inches in cross section for the various tests were 

 subsequently cut according to a prescribed method. One portion of 

 the tie was subjected to the desired treatment in the cylinder while 

 the other portion was retained in its natural condition to be used for 

 the "control" tests, the "control" being the basis of comparison for 

 the tests made upon the treated portion. Tests were made immed- 

 iately after treatment, soaked, air dried, and resoaked after air 

 drying. The tests of strength were for compression, bending, shear- 

 ing, spike pulling and impact. 



In the results presented in thirteen tables the strengths are given 

 in percentages of the control, thus showing clearly the relative val- 

 ues. It is pointed out that on account of the variability in the ma- 

 terial used inherent differences may exist between the treated and 

 control pieces which in themselves may cause a difference of as 

 much as 6 per cent, in the strength. For this reason a variation of 

 6 per cent, or even more, in the tables may not of itself be of any 

 significance. 



