AGKICULTUKAL CHEMISTRY — AGEOTECHNY. 205 



were appreciably attacked wlien boiling in concentrated hydrochloric acid 

 (specific gravity 1.115) for one hour. 



Comparisons were also made of the methods usually employed for dissolving 

 soil constituents, including the Hilgard official, boiling for one hour with hydro- 

 chloric acid (specific gravity 1.115), and the Russian, with 10 per cent hydro- 

 chloric acid (Gedroits) methods. The greatest solubility of soil constituents 

 was obtained with Hilgard's method and the least by the Russian method. The 

 Hilgard method not only showed the highest potassium oxid, aluminum oxid, 

 and silicic oxid content, but also the lax'gest amount of magnesium oxid, ferric 

 oxid, and sulphuric acid. The official method was in some respects second 

 to Hilgard's method. Biotite, chlorite, calcite, apatite, corundolite, magnetite, and 

 augite when boiled with hydrochloric acid (1.115 specific gravity) for one hour 

 were dissolved, but not microcline, orthoclase, plagioclase, muscovite, tourmaline, 

 amphibole, epidote, hypersthene, staurolite, cyanite, rutile, zircon, ilmenite, and 

 granatite. Treatment with a 10 per cent solution of hydrochloric acid for 10 

 hours in the water bath dissolved all the minerals soluble in hydrochloric acid 

 of a specific gravity of 1.115, and had also some effect on microcline. Treatment 

 with hydrochloric acid of a specific gravity of 1.115 for 10 hours dissolved all 

 minerals soluble in the same strength of hydrochloric acid in the one-hour 

 period of boiling and had some effect on microcline, plagioclase, muscovite, and 

 amphibole. By treating with hydrochloric acid of a specific gravity of 1.115 

 according to Hilgard's method for 120 hours in the water bath orthoclase, 

 plagioclase, and the substances soluble in the same strength of hydrochloric 

 acid by boiling for one hour were dissolved, and microcline, muscovite, and 

 amphibole were affected. By the 10-hour treatment and the 120-hour treat- 

 ment granatite was increased, and by the 120-hour treatment with hydrochloric 

 acid staurolite was increased. Crude clay removed from a soil by means of a 

 centrifuge when subjected to hydrochloric acid (specific gravity 1.115) for 1 

 and 120 hours, respectively, showed that the greatest solution of the monoxids 

 took place by the 120-hour exposure. An anomaly was noted in the case of 

 soluble silicic acid, however, because less was found after the 120-hour exposure 

 than after the 1-hour treatment. 



The characterization of soils on the basis of the chemical analysis is discussed. 



Report on the work of the International Commission for chemical soil 

 analysis, A. A. J. von 'Sigmowd (Intcniat. Mitt. Bodenk., 4 (1914), ^'O. 4-5, pp. 

 271-279). — ^A compilation of the most important determinations to be made for 

 judging soils. The references to the literature are given. 



The f undam.ental questions in preparing soil solutions for chemical analy- 

 sis, A. A. J. VON 'SiGMOND {Internal. Mitt. BodenJc, 4 {1914), A'o 4-5, pp. 279- 

 296). — For purposes of completeness these data on methods were submitted with 

 the above report. 



Contribution to methods of soil analyses, R. Albert and O. Boos {Internat. 

 Mitt. Bodenk., 4 {1914), No. 2-3, pp. 181-198).— A report on attempts to simplify 

 existia^ methods for humus, moisture, and specific gravity of soil. 



It was found that the Knop method for humus does not show a sharp end 

 point and the glass parts of the apparatus are often attacked and must be 

 frequently replaced. If the sample of soil is rubbed up gently in a porcelain 

 mortar the method will yield very satisfactory results. The amount of carbon 

 dioxid produced multiplied by 0.471 equals the humus content of the soil. The 

 Wahnschafte suggestion to keep soil in contact with sulphuric acid before the 

 regular oxidation process is deemed a disadvantage rather than an advantage. 



Figures obtained by the elementary analysis method according to Dennstedt " 

 were generally higher than those given by the Knop method. Only in the case 



".inleitung zur vereinfachten Elementaranalyse, Hamburg, 1906, 2. ed., pp. 99, figs. 20. 



