8 COLOMBIAN MAHOGANY. 



PHYSICAL PROPERTIES OF THE WOOD. 



While Cariniana differs widely in its botanical and anatomical 

 characters from true mahogany, its close superficial resemblance to 

 mahogany and its physical properties at once distinguish it as a high- 

 class cabinet wood. The wood does not exhibit true annual layers of 

 growth, a characteristic also of true mahogany, especially that ob- 

 tained from near the southern part of the tree's range. When prop- 

 erly seasoned it does not warp, check, or shrink, while much of the 

 lumber is beautifully figured. It works well, takes a filler readily, and 

 can be highly polished. There is no reason why it should not be 

 employed for all purposes for which true mahogany is used. The 

 wood is hard, heavy (42 pounds to the cubic foot, with a specific 

 gravity 0.674), strong, and tough, and in color and weight compares 

 almost exactly with genuine mahogany. Those who work Cariniana 

 wood observe that it dulls the saws and other tools very quickly, a 

 fact winch first cast suspicion on it as not being real mahogany and 

 led to its study by the Forest Service. The following is a chemical 

 analysis of the wood. 1 



Per cent . 



Insoluble in concentrated acid 53. 4 



Lime 29. 9 



Magnesia and traces of iron and soda 2. 5 



Carbon dioxide, with small amount of unburnt carbon, and phos- 

 phoric acid 16. 2 



A microscopical examination of the wood shows a great abundance 

 of crystals of calcium oxalate and calcium carbonate in the wood- 

 parenchyma fibers (fig. 5, b). These fibers are abundant, and are 

 scattered among the thick-walled wood fibers. The flinty and insolu- 

 ble crystals of calcium oxalate doubtless have a great deal to do with 

 the dulling of the saws experienced in milling tins timber. Moreover, 

 the walls of the wood fibers are very thick (fig. 4, b), leaving only 

 very small cavities, which adds considerably to the density and hard- 

 ness of the wood. 



MINUTE CHARACTERS OF THE WOOD. 



The pores or vessels (fig. 6, a), as seen in transverse section are con- 

 spicuous, though not very numerous, and are evenly distributed 

 throughout, singly for the most part, but occasionally subdivided by 

 partition walls that are either oblique or at right angles to the pith 

 ravs. Seldom are more than two pores grouped radially, in which 

 ease one is always quite small. Solitary pores have small to moder- 

 ately large cavities (0.15 to 0.4 millimeter) with an average of about 

 0.3 millimeter in radial diameter. (Exceptionally small pores, which 

 occur occasionally, are not included in tins average diameter.) The 



1 Made by F. P. Veitch, Chief of the Leather and Paper Laboratory, Bureau of Chemistry. 



