VOL.7, No. 9
THE LIFE LAYER OF THE WORLD
2029
Reid, curator and acting sufiintendent, State Historical Society of North Dakota, who secured for him the illustrations of typical prairie land.
Literature Cited "Available Energy," address before the Society of Chemical (1) R. A. MILLIKAN, Industry, New York, Sept. 4, 1928, and reported in Science, 68,270-84 (Sept. 28, 1928). Astrophysical J., 22, 1 6 5 8 1 (1905). (2) F. R. MOULTON, (3) F. W. CLARKE, "The Data of Geochemistry," 5th edition, Government Printing Office. Wabinptan. D. C.. 1924,. DD. . - - 40-4. (4) ~ ~ d p.l ,34. ( 5 ) C. F. MAEBUT,et al., "Soils of the United States." U. S. Department of Agriculture, BUN. 96 (1913). (6) C. F. MARBUT,"The Relation of Soil Type to Organic Matter," J. Am. ~
Soc. Agron., 21, 943-51 (1929). (7) K. D. GZINKA,"Die Typen der Boden Bildung, ihre Rlassifikation und geograpbische Verehreitung," 1914, 582 pp. Translated by C. F. Marbut. Published by Edwards Bros., Ann Arbor, Mich.. 1928. (8) N. M. Tmantov, "The Genetic Classification of Soils." J. Agr. Sci.. 3, 80 (1909-10). (9) G. W. R o e m s o ~ ,"Pedology as a Branch of Geology," Geol. Mag., 61, 444 (1 \ - 924) - - ., .
DARWIN, s "Journal of Researches into the Natural History and (10) C n l l ~ ~ E Geology of the Countries Visited during the Voyage of H.M.S. Beagle Round the World." 2nd edition. D. Appleton & Co., New York and London, Chapters VIII. X, and XI, 1845. "Soils," The Maanillan Co., New York City, 1906, p. 420 (11) E. W. HILGARD, (12) H. H. BENNETTand R. V. ALLISON,"The Soils of Cuba," published by Tropical Plant Research Foundation, Washington, D. C., 1928. (13) P. L. GnE, "Colloid Symposium Monograph," Val. 3, Chemical Catalog Co., New York City, 1925. (14) J. T. WAY,"On the Power of Soils to Absorb Manure," J. Roy. Agr. Soc., 11, 313-79 (1850); Ibid., 13, 123-243 (1852). and N. H. J. MILLER,"The Direct Assimilation of In(15) H. B. HUTCHINSON organic and Organic Forms of Nitrogen by Higher Plants." J. Agr. Sci., 4, 282-302 (1912). (16)
A. F. HECKand W. L. WmnNc, "The Assimilation of Phosphorus from Phytin by Red Clover," Soil Science, 24, 1 (1927). , of Certain Carbohydrates on Green Plants," (17) L. K N ~ S O N"Influence Cornell Agr. Expt. Sfa. Memoir, No. 9 (1916). (18) J. B. COLLIP,et nl., J. B i d . Chem., 63, 395439 (1925). (19) J. A. SCOTT WATSON,"The Agricultural Revolution in Scotland, 17501810," reprinted from "The Transactions of the Highland and Agricultural Society of Scotland," 1929. DARWIN, "Earthworms and Vegetable Mould," London. 1881. (20) CHARLES
Writing with Water. Tannic acid reacts with ferric salts to produe a nearly black precipitate. This reaction, however, can only take place when the chemicals are dissolved in water. By writing with water on a paper over which the above chemicals have been spread, the effects described are obtained.-The Science Classraom
