1. Comptes rendus, Tome 110, p. 1271.
2. Wyatt, Phosphates of America, p. 66.
3. Engineering and Mining Journal, August 23, 1890.
4. American Journal of Science, Vol. 41, February, 1891.
5. Preliminary Sketch of Florida Phosphates, Author’s edition, pp. 18, et seq.
6. Journal für praktische Chemie, 1st series, Band 38, S. 388.
7. Annual Report Connecticut Experiment Station, 1890, p. 72.
8. Annual Report Massachusetts Experiment Station, 1887, p. 233.
9. Bulletin 21, Rhode Island Experiment Station, 1893.
10. Chemical Composition of Food-Fishes. Report of U. S. Commissioner of Fish and Fisheries, 1888, pp. 679 et seq.
11. G. Brown Goode, American Naturalist, Vol. 14, July, 1890.
12. Comptes rendus, Tome 101, 1885, pp. 65, et seq.
13. Royal Agricultural Society Journal, Vol. 13, 1852, pp. 349 et seq.
14. Gîtes Mineraux, par Fuchs et DeLauny, Tome 1, p. 425.
15. El Salitre de Chile; René F. LeFeuvre y Artūro Dagnino, 1893, p. 12.
16. Crampton, American Chemical Journal, Vol. II, 1890, p. 227.
17. Potash, pamphlet of German Kali Works, pp. 3, 4.
18. Gîtes Mineraux, p. 429.
19. Bulletin of the Philosophical Society of Washington, Vol. II, p. 142.
20. Handbook for the Department of Geology of the U. S. National Museum, by Geo. P. Merrill.
21. Vid. supra, p. 506.
22. Vid. supra, Plate 120.
23. Merrill, op. cit. p. 521.
24. Merrill, op. cit. p. 536.
25. Merrill, op. cit. p. 545.
26. Merrill, op. cit. p. 547.
27. Mineral Physiology and Physiography, p. 251.
28. Bulletin No. 52, United States Geological Survey, p. 16.
29. bis (p. 48), Vid. supra, p. 38.
30. The Formation of Vegetable Mold through the Action of Worms.
31. Rocks and Soils, pp. 131–2.
32. Comptes rendus, Tome 110, p. 1370.
33. Bulletin No. 83, California Experiment Station.
34. Geological Magazine, Vol. 7, No. 6, pp. 291–92.
35. Wiley, Agricultural Science, 1893, pp. 106 et seq.
36. Travaux de la Société des Naturalistes St. Petersburg, Tome 20, 1889.
37. Rocks and Soils, p. 134.
38. Beilstein’s Handbuch der Organischen Chemie, Band I, Ss. 891–2.