76 USES OF COMMERCIAL WOODS OF THE UNITED STATES. 



ARIZONA PINE (Pinus arizonica). 

 PHYSICAL PROPERTIES. 



Weight of dry wood. 31.4 pounds per cubic foot (Sargent). 



Specific gravity. 0.5 (Sargent). 



Ash. 0.2 per cent of weight of dry wood (Sargent). 



Fuel value. 68 per cent that of white oak (Sargent). 



Breaking strength (modulus of rupture). 9,100 pounds per square inch, or 

 57 per cent that of long-leaf pine (Sargent). 



Factor of stiffness (modulus of elasticity). 1,153,000 pounds per square inch, 

 or 54 per cent that of longleaf pine (Sargent). 



Character and qualities. Light, soft, not strong, rather brittle, compact; 

 summerwood broad, very resinous, conspicuous ; resin passages numerous, large ; 

 medullary rays thin, obscure ; color light red, or often yellow, the sapwood 

 lighter yellow or white. 



Groivth. Height, 75 to 90 feet ; diameter, 18 to 30 inches. 



SUPPLY AND USES. 



The range of the Arizona pine is restricted to the mountains of 

 southern Arizona, where it attains its best development on rocky 

 ridges from 6,000 to 8,000 feet above sea level. It is the prevailing 

 forest tree near the summit of the Santa Catalina Mountains. In 

 general appearance it closely resembles the western yellow pine, and 

 the two species are frequently cut, milled, and sold in that region 

 without distinction; but this holds only for the better grades of 

 Arizona pine logs. Much of the timber is of small size and yields 

 inferior lumber. The wood supplies a considerable local demand for 

 fuel. 



MEXICAN WHITE PINE (Pinus strombiformls). 



PHYSICAL PROPERTIES. 



Weight of dry wood. 30.4 pounds per cubic foot (Sargent). 



Specific gravity. 0.49 (Sargent). 



Ash. 0.26 per cent of weight of dry wood ( Sargent ) . 



Fuel value. 65 per cent of longleaf pine (Sargent). 



Breaking strength (modulus of rupture). 10,800 pounds per square inch, or 

 61 per cent that of longleaf pine (Sargent). 



Factor of stiffness (modulus of elasticity). 1,154,000 pounds per square inch, 

 or 54 per cent that of longleaf pine (Sargent). 



Character and qualities. Light, hard, not strong, close ringed, compact ; 

 springwood thin, resinous, not conspicuous; resin passages large, not numerous; 

 medullary rays numerous, obscure ; color, light red, the sapwood nearly white. 



Growth. Height, 75 to 90 feet ; diameter, 12 to 18 inches. 



SUPPLY AND USES. 



The Mexican white pine's northern limit is in southwestern Mexico 

 and southern Arizona, and the tree is most abundant at altitudes of 

 from 6,000 to 8,000 feet. Its range extends north and south through 



