_Iodometric Estimation of Nitric Acid_, pp. 543–548.—Method of DeKoninck and Nihoul; Method of Gooch and Gruener. _Estimation of Nitric and Nitrous Acids by Colorimetric Comparison_, pp. 548–570.—Delicacy of the process; Hooker’s carbazol method; Phenylsulfuric acid method; Estimation of nitric in presence of nitrous acid; Metaphenylenediamin method for nitrous acid. Sulfanilic acid test; Naphthylamin process; Use of starch as indicator; Method of Chabrier; Ferrous salt method; Potassium ferrocyanid method; Collecting samples of rain water. _Determination of Free and Albuminoid Ammonia_, pp. 570–575.—Nessler process; Ilosvay’s reagent; Authorities cited in part seventh. PART EIGHTH. _Special Examination of Waters_, pp. 576–583.—Total solid matter; Estimation of chlorin; Estimation of carbon dioxid; Boric acid. _Special Treatment of Muck Soils_, pp. 583–591.—Sampling; Water content; Organic carbon and hydrogen; Total volatile matter; Estimation of sulfur; Estimation of phosphoric acid; Estimation of humus; Special study of soluble matters in muck. _Unusual Constituents of Soil_, pp. 580–593.—Estimation of copper; Estimation of lead; Estimation of zinc; Estimation of boron; Authorities cited in part eighth. Index, pp. 594–607. * * * * * =CORRECTIONS.=—Page 112, second line from bottom, read “Fig. 14” instead of “13.” Page 158, insert “and determining soluble matters therein” after “flow” in paragraph =172=, third line. Page 468, paragraph =423=, read “calcium carbonate about 200 milligrams,” instead of “calcium carbonate, or gypsum fifty milligrams.” Page 557, read “red-yellow” instead of “blue” in seventh line from bottom. ILLUSTRATIONS TO VOLUME FIRST. Page. Plate, figures 1–6. To face 29 Figure 7. Microscopic structure of sandstone 36 „ 8. Microstructure of crystalline limestone 39 „ 9. Microstructure of Gneiss 40 Plate, figure 10. View on the broad branch of Rock Creek, 48 Washington, D. C., to face Figure 11. 82 „ 12. 84 „ 13. Regnault’s apparatus for determining the specific heat 105 of soils „ 14. Soil thermometer 113 „ 15. Zalomanoff’s apparatus for determining absorption of 126 salts by soils „ 16. Müller’s apparatus to show absorption of salts by 127 soils Plate, figure 17. Capacity of the fine soil for holding moisture. 136 Method of Wolff modified by Wahnschaffe, to face Figure 18. Fuelling’s apparatus 140