No. 4, February, 1922] SOIL SCIENCE 305 



nesium nitrates (0.1 N) had practically no effect on oxidation, while nitrates of calcium, 

 barium, manganese, and iron (ferric) decreased it. Potassium chloride (0.02 X and 0.002 N) 

 had no effect on oxidation, while manganese chloride in these concentrations increased it. 

 Tartrates, oxalates, citrates, acetates, and carbonates increased oxidation, this being due 

 in part at least to the low acidity of the mixtures of bark, pyrogallol, and salt. Marked 

 decrease in oxidation is not necessarily accompanied by high acidity of the mixtures. Ions 

 other than the hydrogen and hydroxyl may be important in regulating oxidase activity. In 

 neutralizing hydrogen or hydroxyl ions, it is important to take into consideration, in the study 

 of oxidase activity, the possible effect of the salts formed thereby. The chlorides which 

 retard the combustion of tobacco at high temperatures also retard the o.xidase action at low 

 temperatures. The effect of the alkali chlorides upon oxidase activity suggests a practical 

 application in preventing the browning of fruits and vegetables during their preparation for 

 canning, preserving, or drying. — Authors' Abstract. 



ELECTRICITY AND MECHANICAL AGENTS 



197G. S., J. [Rev. of: Baines, E. A. Germination in its electrical aspect. xx+lSo p., 

 ISO fig. Routledge: London, 1921.] Jour. Bo t. 59: 237-238. 1921. 



MISCELLANEOUS 



1977. Prixgsheim, Ernst G. tJber die Herstellung von Gelatinefarbfiltern fiir physio- 

 logische Versuche. [On the preparation of gelatine color filters for physiological experiments.] 

 Ber. Deutsch. Bot. Ges. 37: 184-186. 1919. — Attention is called to the method, described in 

 an earlier paper by the author, of securing monochromatic color filters by staining fixed, 

 unexposed photographic plates in solutions of various dyes. The difficulty encountered in 

 eliminating the extreme red end of the visible spectrum was overcome by screens prepared by 

 pouring gelatin dissolved in a solution of Grtibler's soluble Berlin blue upon clean glass 

 plates. A list is given of the stains used and indications are furnished concerning the light 

 absorbed and that allowed to pass by each of the stains. — R. M. Holman. 



SOIL SCIENCE 



J. J. Skinner, Editor 

 F. M. ScHERTZ, Assistant Editor 



(See also in this issue Entries 1443, 1459, 1462, 1488, 1651, 1660, 1949) 



GENERAL 



1978. Alway, F. .!., P. R. Mc^Iillex, axd C. O. Rost. A successful cooperative experi- 

 ment on a potash-hungry peat of doubtful lime requirement. Jour. Amer. Peat Soc. 14": 5- IS. 

 1921. — A typical Minnesota peat soil, having an acid reaction and approximately 1 per cent 

 of lime, contained sufficient nitrogen and lime for clover, barley, flax, corn, sunflowers, pota- 

 toes, beets, and cabbage. — G. B. Rigg. 



1979. AxGELis d'Ossat, G. de. L'argilla colloidale del terreno agrario. [The colloidal 

 clay of agricultural soils.] Staz. Sper. Agrarie Ital. 54: 214-224. 1921. — The question is 

 studied in general, the aim being to show that many of the properties of soil are due not only 

 to the quantity of colloidal clay contained therein, but to the response of the relatively small 

 percentage of this substance to the influence of the various environmental factors. Heat and 

 pressure are regarded the most important and are to be considered with respect to the fol- 

 lowing manifestations: heat manifested as temperature, sunlight (thermic, actinic, and 

 luminous rays each playing a specific role), evaporation, and freezing. Pressure, considered 

 apart from its heat effects, is also of great importance as is demonstrated by the stability 

 which some metamorphic rocks and shales assume when submitted to it. Reversible and 

 irreversible changes which take place in ordinary soils in the deep layers should here be 

 ascribed to this action. — A. Bonazzi. 



