120 EXPEEnVTEN^T STATION RECOED. (Vol. 85 



gressive heating of clay marl from 700 to 800° C. in an electric furnace led to 

 the conclusions that the water of hydration is completely eliminated by heating 

 to a temperature of 700°, and that the decomposition of carbonates and the 

 eUmination of carbon dioxid takes place rapidly at 800°. It was also found 

 that the density tended to increase with progressive heating beyond 800°. 



Improving acid soils, A. W. Blaib {New Jersey Stas. Circ. 54 (1916), pp. 

 S-11, pis. 4).— This is a popular discussion of soil acidity and its causes, and its 

 correction by the use of calcium carbonate, burned lime, hydrated lime, ground 

 oyster shells, burned oyster-shell lime, unleached hardwood ashes, and basic 

 slag. It is estimated that about four-fifths of the farm lands of New Jersey now 

 under cultivation are acid to an extent that materially decreases crop yields. 



Investigations of soil air on upland moors, A. Densch (Mitt. Ver. Ford. 

 MoorkuUur Deut. Reiche, 33 {1915), Nos. 21, pp. ^-413; 22, pp. 423-428).— 

 Investigations on the amount and composition of the soil gases of upland moors 

 are reported. The soil samples were taken at depths of from 16 to 20 cm. 

 (6.3 to 7.9 in,). 



It was found that the absolute content of gas in upland moor soils, even with 

 a high water content, was not less than that of mineral soils. The processes of 

 oxidation and decomposition in cultivated upland moor soils in no case produced 

 a large enough increase in carbon dioxid or decrease in oxygen content of the 

 soil gas to influence plant growth unfavorably. Cultivated upland moor soil 

 had almost identically the same oxygen and carbon dioxid contents as mineral 

 soils. The composition of the gases of upland moor meadow soils corresponded 

 approximately to that of lowland moor meadow soils. 



Soluble nonprotein nitrogen of soil, R. S. Potteb and R. S. Sntdee (U. S. 

 Dept. Agr., Jour. Agr. Research, 6 {1916), No. 2, pp. 61-64)- — Analyses made at 

 the Iowa Experiment Station of 5-gm. portions of silt loam soil, containing 0.3 

 per cent nitrogen, for alkali-soluble and soluble nonprotein nitrogen are reported. 

 " The general procedure followed was to determine the nitrogen in the alkali 

 extract of soU with and without added material and the determination of nitro- 

 gen in the filtrate from the precipitate of the proteins in the alkali extract of 

 soil with and without added material." The substances added " were chosen to 

 represent classes of compounds which conceivably might be in soils." It was 

 concluded that " if the results with the pure proteins be considered. It is prob- 

 able that tlie alkali extract as a whole contains no definite group of compounds. 

 From the results obtained by the precipitation of the alkali extract with tri- 

 chloracetic acid it would seem that the soluble nonprotein fraction may contain 

 most of the simpler nitrogenous compounds, and therefore its determination 

 would give an index of the degree of decomposition of the organic matter in 

 the soil." 



The nature of humic acid, S. Od£n {Ark. Eemi, Min. och Geol., 5 {1913- 

 1915), No. 5-5, Art. 15, pp. IS; abs. in Internat. Inst. Agr. [Rome'\, Mo. Bui. Agr. 

 Intel, and Plant Diseases, 6 {1915), No. 5, pp. 660, 661; Chem. ZentU., 1915, I, 

 No. 26, p. i3S5).— Studies along the lines of work previously noted (E. S. R., 

 32, p. 813) with so-called black peat, dried sphagnum moss, and forest humus 

 are reported, in which the electrical conductivity of a dilute ammonia solution, 

 with and without the extract from the three types of organic matter, was 

 observed. 



Adsorption of ammonia was found to take place in the case of the extracts 

 from all three samples of organic matter. At the same time considerable salt 

 formation occurred in two cases where the dark humus was abundant, but not 

 in the case of the dried sphagnum moss extract. These results are taken to 

 Indicate that one or more acids must exist in humua. 



