Current Literature. 67 



The great demand for true mahogany has so depleted the 

 supply that full twenty other woods of varying resemblance are 

 being substituted for it. "Colombian mahogany" affords one of 

 the best imitations for true mahogany now on the market, though 

 botanically the trees are widely separated. 



The "Colombian mahogany" is an excellent cabinet wood. 

 When properly seasoned it does not warp, check or shrink ; much 

 of the lumber is handsomely figured and of good color. The 

 wood is hard, heavy, strong, tough, susceptible of high polish and 

 takes a filler readily. It works well but dulls the saws and other 

 tools very quickly. 



Much of this publication is devoted to the botanical charac- 

 ters of the tree and to the minute anatomy of the wood. The 

 important features distinguishing this wood from that of true 

 mahogany are emphasized in the text and illustrated by draw- 

 ings. 



S. J. R. 



A Visual Method for Determining the Penetration of Inorganic 

 Salts in Treated Wood. By E. Bateman. Circular 190, Forest 

 Products Laboratory Series, U. S. Forest Service. Washington, 

 D. C. 191 1. Pp.5. 



This method has been devised to enable a determination of the 

 depth of penetration without the tedium and expense of a wood 

 analysis. 



Where zinc chloride is used in the preservative treatment the 

 freshly cut surface of a disk of the treated wood is dipped for not 

 longer than ten seconds in a one per cent, solution of potassium 

 ferrocyanide. After the excess is removed by blotting paper the 

 disk is dipped into a one per cent, solution of uranium acetate 

 and allowed to dry. Since zinc chloride will decolorize the dark 

 red uranium ferrocyanide (which is formed as a result of the 

 two dippings) the disk face will be dark red where the treating 

 fluid has not penetrated, and elsewhere slightly whiter than the 

 natural wood. This visual method of detection can be used 

 except with woods whose natural color masks that of the uranium 

 ferrocyanide. 



In the case of metals whose salts are characteristically colored 



