HARDvVOOD RECORD 



27 



scope. One glance was enough to tell tliat it was not birch, for 

 here were rows of large thick-walled npeu pores which are never 

 found in birch. The presence of a very broad ray proved it to be 

 oak and the character of the pores an.l other features referred it 

 unerringly to the black or red oak group, though the exact species 

 could not be determined. 



Sometimes holly is made into rulers and similar articles and sold 

 as boxwood. Under the microscope, however, holly is more distinctive 

 among hardwoods than Douglas fir among softwoods, for its wood 

 fibers are marked with spirals. Yellow poplar and cucumber often 

 look very much alike but are distinguished by the markings on their 

 vessel walls — being ladder-like or scalariform in cucumber and 

 ordinary bordered pits in the other. Basswood can be distinguished 

 from the sapwood of yellow poplar by the presence in the former of 

 tangential lines of wood parenchyma as well as by indistinct cross- 

 markings on longitudinal surface due to the wood elements (except 

 r.avs) being in storied arrangement. The tiniest shaving of birch can 



be told from maple by the fact that under the microscope the vessel 

 perforations of tlie former are seen to be crossed with bars (scalari- 

 form) while in the latter they are simple. Willow can be told from 

 Cottonwood by the fact that the marginal ray eeUs are irregular and 

 difi'erent from the rest of the ray cells, while in eottonwood they are 

 all alike and elongated in one direction. Hackberry can be separateil 

 from elm in exactly the same manner. 



It should not be inferred from these examples that it is possible 

 in all cases to identify a wood specifically. Often the best one can 

 do at present is to name a group to which it belongs. This is 

 largely true of the oaks, hard pines, cottonwoods, and willows. 

 Even in the important case of the southern pines no one constant 

 feature of distinction has been found, but one must rely instead 

 upon a number of characteristics taken together, and all too often 

 these are insufficient for absolute certainty. The art of wood 

 identification is in its . infancy, but with , increased interest in the 

 subject, a great many present uncertainties will be cleared up. 



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Balsa Wood of Commerce 





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Balsa, guano, corkwood, and down tree are different names applied 

 to a soft-wooded tree botanieally known as Ochroma lagopus of the 

 sterculiaeeous family of plants. The tree often attains a height 

 of from sixty to seventy feet, and sometimes a diameter of two feet. 

 Balsa is the name of a raft or float in tropical America, which the 

 natives construct out of this wood, and the tree, therefore, came to 

 be called balsa. It is called guano or down tree because in Porto 

 Rico it is one of the most important economic trees, for the cotton 

 surrounding its seeds is the ' ' guano " or ' ' down ' ' with which nearly 

 all of the natives' pillows and cushions are stuffed. In the American 

 markets corkwood is the name most generally applied to this wood, 

 because it is as light as cork and often used for the same purposes. 



Balsa is a very common tree, particularly along the sea shores in 

 the West Indies and Central America. It is a commercial tree in 

 Porto Bieo, especially on the edge of mangrove swamps or in other 

 inaccessible locations, often growing with its roots in contact with 

 salt water. While it demands a damp soil, it frequently grows well 

 in the poorer soils in the hills away from the sea shore. The tree 

 has many of the characteristics of the ceiba or silk-cotton tree 

 {Eriodendroii anfraciuosum) so common in the landscape of tropical 

 America. The balsa is a much smaller tree, however, than the ceiba, 

 and its distribution is restricted to tropical America. The ceiba tree 

 is known within the tropics all around the world. 



Balsa makes a very rapid growth and has striking foliage and 

 magnolia-like flowers. The fruit consists of a five-celled capsule 

 about six inches in length and about one inch in diameter. As soon 

 as these pods are ripe,, the cells split open longitudinally and the seeds 

 with their silk cotton protrude and spread over the whole surface, 

 giving the appearance of a hare 's foot. This characteristic is alluded 

 to in the specific name lagopus, which signifies hare's foot. The 

 chestnut brown fiber which surrounds the seeds of this tree is gathered 

 and packed into bales and sold at a few cents per pound. It is 

 readily removed from the capsules, but it is almost impossible to 

 free it entirely from the seeds. This silk cotton is said to be very 

 valuable as a stuffing material. It keeps free from insects and does 

 not wad to the same extent as pure cotton, and is used extensively 

 for making pillows and mattresses, and to a smaller extent for making 

 garments. The bark also yields a fiber which may become a staple 

 product for rope-making. The bark is used locally for the tannin it 

 contains, and both the bark and root are used medicinally. 



The wood is nearly white or slightly tinted with red, showing 

 practically no distinction between heart-wood and sap-wood. It has 

 a silky texture, is rather coarse but straight-grained, and is the 

 lightest of all woods — even lighter than true cork. A sample of 

 balsa from Trinidad exhibited at Philadelphia in 1876 had a specific 

 gravity of .120, or about seven and one-half pounds per cubic foot. 

 Wiesner, a German authority, gives the specific gravity of this wood 

 to be .250. Individual variability and the difficulties of determining 



the specific gravity of so porous and absorbent a wood as this make 

 it unwise to accept either one of these figures as invariable. Cork- 

 oak bark {Quercns sxtber) has a specific weight of .240, but it appears 

 that some samples of corkwood are considerably lighter than commer- 

 cial cork, which is markedly lighter than any other wood, with the 

 exception of the wood of a small and unimportant tree {Eerminiera 

 elaphroxylon) growing in Central and East Africa. 



The reason for this extreme lightness of the corkwood is to be 

 looked for in connection with its structure and the softness of its 

 tissue, which is easily compressible under the thumb-nail. It is very 

 fibrous and often exceedingly difficult to work because of the fibers 

 that impede the action of the tools. Balsa is commonly employed as 

 a substitute for cork, both for stopping bottles and for floats of 

 fishing nets. In Trinidad and other places it forms an article of 

 commerce with fishermen, who use it in place of true cork on their 

 nets. It has served only to a very limited extent for stopping bottles, 

 since the high elasticity, impermeability and resistance to decay, so 

 characteristic of true cork, are not possessed by this wood. 



The very buoyant rafts or balsas, the unsinkable properties of 

 which caused such surprise among the discoverers of America, are like- 

 wise made of it. The Indians used it to make their canoes bouyant, 

 and it was at one time considered very desirable for pontoons for 

 dry docks. The wood has been experimented with and found suit- 

 able for making life preservers. For this purpose the wood must 

 be heated with paraffin, which, together with other expenses in pre- 

 paring it, renders the cost of the material equal to that of the regular 

 cork. In an untreated state the wood is not very durable. 



Balsa is imported into tlie United States from Cuba, Porto Rico 

 and Trinidad. A good many logs go to England, chiefly from Trini- 

 dad. It is claimed by dealers that the bulk of balsa wood comes 

 from Ecuador and Peru in the form of logs from sixteen to thirty 

 inches in diameter and from ten to twenty feet in length. The wood 

 is sold at prices ranging from forty to sixty cents per cubic foot. 

 It is doubtful, however, whether the species from Ecuador and Peru 

 is the same as that growing in the West Indies. Some writers claim 

 that the wood from Soutli America is Ochro^na piscatoria, but this 

 cannot now be definitely determined. An examination of the woods 

 alone, however, indicates tliat they are from two distinct trees. The 

 West Indian kind is lighter in weight and color and has less pro- 

 nounced pith-rays. 



The annual rings of growth, though nearly invisible to the naked 

 eye, are evident on an examination of the wood under the hand lens, 

 being partly caused by the occurrence of a broken line of slightly 

 larger pores at the beginning of the year's growth. The pith-rays 

 are quite conspicuous on a smooth transverse section; they are also 

 plainly visible on the radial surface, and give figure to the wood, 

 resembling the character of beech or sycamore, only in balsa they are 

 more numerous. 



