It might seem absurd to suppose that the addition of 100 pounds of sodium nitrate would prove useful to a plat containing already many tons of nitrogen; but the nitrate is at once available and its beneficial influences are easily seen. The full value of silt analysis will only be appreciated when many typical soils from widely separated areas are carefully studied in respect of their chemical and physical constitution and the character of the crops which they produce. AUTHORITIES CITED IN PART FOURTH. Footnote 121: Annual Report, Connecticut Agricultural Experiment Station, 1887. Footnote 122: American Journal of Science, March 1879, p. 205. Footnote 123: Bulletin, No. 4, United States Weather Bureau, p. 19. Footnote 124: Chemical News, Vol. 30, August 7, 1874, p. 57. Footnote 125: American Journal of Science, Vol. 29, 1885, p. 1. Footnote 126: American Journal of Science, Vol. 37, (1889), p. 122. Footnote 127: Proceedings National Academy of Science, Baltimore Meeting, 1892. Footnote 128: Manuscript communication to author. Footnote 129: Division of Chemistry, Bulletin 38, p. 200. Footnote 130: Anleitung zur Wissenschaftlichen Bodenuntersuchung, S. 23. Footnote 131: Die Landwirtschaftlichen Versuchs-Stationen, Band 38, Ss. 309, et seq. Footnote 132: Berichte der deutschen chemischen Gesellschaft, Band 15, S. 3025. Footnote 133: Connecticut Agricultural Experiment Station, Annual Report, 1886, pp. 141, et seq. Footnote 134: König, Untersuchung Landwirtschaftlich und Gewerblich Wichtiger Stoffe, S. 7. Footnote 135: Wahnschaffe, Anleitung zur Wissenschaftlichen Bodenuntersuchung, S. 25. Footnote 136: Vid. 15, S. 24. Footnote 137: König, op. cit. 14, S. 13. Footnote 138: Tenth Census of the United States, Vol. 3, pp. 872–3. Footnote 139: Wahnschaffe, op. cit. 15, S. 26. Footnote 140: Le Stazioni Sperimentali Agrarie Italiane, Vol. 17, pp. 672, et seq. Footnote 141: Vid. 13. Footnote 142: Encyclopedie Chimique, Tome 4, pp. 155, et seq. Footnote 143: Annales de la Science Agronomique, 1891, Tome 1, Seconde Fasicule, pp. 250, et seq. Footnote 144: Vid. 22. Footnote 145: Petermann, L’Analyse du Sol., p. 15. Footnote 146: Vid. 20. Footnote 147: Zeitschrift für analytische Chemie, Band 3, Ss. 89, et seq. Footnote 148: Zeitschrift für analytische Chemie, Band 5, Ss. 295, et seq. Footnote 149: Bulletin de la Société des Naturalistes de Moscou, Tome 40, pp. 324, et seq. Footnote 150: Journal für Landwirtschaft, Band 38, Theil 2, S. 162. Footnote 151: Connecticut Agricultural Experiment Station, Annual Report, 1887, pp. 145, et seq. Footnote 152: Division of Chemistry, Bulletin No. 38, pp. 60, et seq. The figures are from original drawings under the direction of Prof. Hilgard. Footnote 153: Op. cit. supra, pp. 65–69. Footnote 154: Op. cit. 13, p. 150. Footnote 155: