. Bulletin. Forests and forestry -- United States. 14 A PRTMER OF FORESTRY. tben either used at once in growth or stored away until the proper moment arrives. This is the general rule, but it is believed that in some cases food taken u^) by the roots can be used without first beinjr ST?. ' . .1 . }-,/ ' ^ V. iw-' digested in the leaves. THE COMPOSITIOX OF WOOD. Wood is made up chietly of carbon, oxy- gen, and hydrogen. Fig. 10.âiJaik of the Western Hemlock. Washington Forest Eeserve. When perfectly dry, about half its weight is carbon, and half oxygen and hydrogen, in almost the same proportio
. Bulletin. Forests and forestry -- United States. 14 A PRTMER OF FORESTRY. tben either used at once in growth or stored away until the proper moment arrives. This is the general rule, but it is believed that in some cases food taken u^) by the roots can be used without first beinjr ST?. ' . .1 . }-,/ ' ^ V. iw-' digested in the leaves. THE COMPOSITIOX OF WOOD. Wood is made up chietly of carbon, oxy- gen, and hydrogen. Fig. 10.âiJaik of the Western Hemlock. Washington Forest Eeserve. When perfectly dry, about half its weight is carbon, and half oxygen and hydrogen, in almost the same proportion as in water. It contains also about 1 part in 100, by weight, of earthy constituents, and nitrogen to the same amount. When wood is burned, all these materials disappear into the air except the earthy con- stituents. Now tbe nitrogen and water taken up by the roots were originally in the air before they reached the ground. It is true, there- fore, that when wood is burned those parts of it which came from the air go back into it in the form of gas, came from the soil remain behind in n: 1 ^H i\ * 1 %â ⢠I .^B â > ^ I Fig. 11.âAVoodand bark of the Western Yellow Pine. Thecntisper- Ijendicular. and the specimen stands as it did in the tree. The jiicture shows the di- vision of the bark into scales by the succes- sive layers of cork cambium. The true cambium is between wood and l)ark. while those which the form of Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Division of Forestry. Washington : G. P. O.
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