Part 2 — SUMMARY AND CONCLUSIONS

(1) The true lignum-vitae of commerce belongs to the family Zygophyllaceae, of which only three genera, namely, Guaiacum, Porlieria, and Bulnesia, have representatives of tree size, and these are confined to the tropical and sub-tropical regions of the Western Hemisphere. Porlieria is of no commercial importance.

(2) The genus Bulnesia, with its several species, is confined to South America. Bulnesia arborea Engl., the only species of present commercial importance, grows in Colombia and Venezuela, and supplies the wood known as “vera” or “Maracaibo lignum-vitae.” It is sometimes used as a substitute for the genuine but is considered inferior.

(3) The true lignum-vitae is produced only by species of Guaiacum, of which six have been described by botanists. The commercial range of this genus includes the West Indies, Mexico, Central America, and the coastal region of northern South America. It is not definitely known which species supply the Mexican and Central American wood of commerce.

(4) Lignum-vitae is one of the heaviest woods in the world. The weight (oven-dry) per cubic foot of the heartwood is usually between 75 and 80 pounds. The wood has been an article of trade for more than four centuries. It was formerly supposed to possess remarkable curative powers but is now little employed in medicine. Its principal uses are for bearings (especially for lining the stern tubes of steamships), sheaves, caster-wheels, bowling balls, and miscellaneous articles of turnery. During the war there was an unusual demand for this wood in the shipbuilding industry.

(5) The properties which make lignum-vitae valuable are great density and hardness, extreme toughness, and resistance to wear. The large resin content of the wood acts as a preservative and a natural lubricant, thus making it especially adapted for service under water, as in the case of propeller bushings and water-wheel work.

No wood has been found which is a satisfactory substitute for the more exacting uses to which true lignum-vitae is so eminently suited.

(6) The woods of the Zygophyllaceae can be readily distinguished from all others by the fineness of the “ripple marks” (about 250 per inch), the density and grain of the wood, and the peculiar fragrant resin content. The woods of Guaiacum and Bulnesia can be readily separated by noting the arrangement of the pores as they appear under a hand lens. The different kinds of true lignum-vitae logs can best be separated by their size and by the appearance of the bark.

(7) Dealers have no difficulty in getting an abundant supply of genuine lignum-vitae logs. Although the more conveniently located timber has in many places been cut out, increased prices have made it possible to secure timber previously considered inaccessible. The supply appears adequate to meet the demands for a great many years.

ACKNOWLEDGMENT

The writer is indebted to various dealers and wood-users for valuable assistance in the preparation of this paper. Particular acknowledgment is made of the invaluable services rendered by Mr. C. D. Mell of New York City.