SOILS — FERTILIZERS. 715 



ronditions. The results sbowetl thiit the marked effect of such solutions on the 

 liermeability is due to the puddling of the soil and the consequent destruction 

 of the crumbly structure, the breaking down of zeolitic materials, and changes 

 in the volume of the soil colloids. 



Studies in the rotations, L. R. Waldron and O. Grace (North Dakota Sta., 

 Rpt. Dickinson Siibsta., 1909, pp. 39-59. figs, -i).— The results of a mechanical 

 analysis of the soil and of determinations of soil moisture under different 

 methods of cropping in the rotation experiments carried on in cooperation with 

 the Bureau of riant Industry of this Department are reported and discussed. 



Data are also given for the precipitation and evaporation during the growing 

 seasons from 1907 to 1909. The latter show that as a general rule the evapora- 

 tion varies inversely as the precipitation. With the precipitation during the 

 growing season. May to September, 11.95 in. in 1907, 10.63 in. in 1908, and 

 17.17 in. in 1909 the corresponding evaporation was 24.-53, 27.48, and 23.83 in. 



Yields of corn, wheat, oats, and barley on the moisture conservation plats are 

 reportetl, but the results are not considered conclusive. 



The free humus acids of upland moors, A. Baumann and E. Gully (Mitt. 

 K. Baijr. Moorkultuninst., 1910, Xo. .',, pp. 31-156, figs. 8). — This is an account 

 of a detailed investigation urdertaken to determine whether the so-called free 

 "humus acids" and "sphagnum acids" are identical, the relation of colloids to 

 the acid reactions of sphagnum and peat moss, and the absorptive properties of 

 these substances in relation to acid conditions. 



The investigations showed that there are no free humus acids in peat moss, 

 but that the acid reactions observed are due to the absorbent power of the col- 

 loids of the cell covering of the hyalinesphaguum cells. The general conclusion 

 is drawn that there are no free humus acids in upland soils, but that the absorb- 

 ent properties of the sphagnum bring about conditions which indicate the pres- 

 ence of acids. 



The author maintains that it is not possible to determine directly acid or 

 basic conditions by means of indicators in either insoluble substances like sphag- 

 num and peat moss or in pseudosolutions, but only in homogeneous solutions. 



The covering of soil particles, J. Dumont iCoinpt. Raid. Acad. Sci. [Paris'], 

 l.',9 {1909), No. 23. pp. 1087-10S9; abs. in Chcm. ZcntbL, 1910, I. No. 6, p. .',69).— 

 The author studieil these coverings or crusts by treating a soil, poor in lime, 

 with oxalic acid and ammonia. It was found that like quantities of sand con- 

 tained more of the crust in proportion to the fineness of the particles, and that 

 the crust consisted of the same materials, namely, fine sand, silt, and colloid 

 substances, as are separated by ordinary methods. Compr.ring the physical 

 composition of these crusts with that of the soil from which tlu\v were formed. 

 It was found that the ci'usts contained ten times as much humus and five times 

 as much clay as the soil as a whole. The quantitative composition of the crust 

 appeared to depend absolutely upon that of the soil. 



The causes of the formation of hardpan (ortstein), A. Mayer (Fiililing's 

 handle. Ztg., 50 (1910), No. 9, pp. 315-320).— In this article the author shows 

 how hardpan is formed in the lower layers of the soil by the accumulation of 

 humus and basic constituents removed from the upper layers of the soil. These 

 constituents are dissolved l)y the rain water which becomes saturated with the 

 humus acids. The exhausted sands of the upper layers of the soil constitute the 

 so-calle<l "bleisand." 



Analyses of "bleisand," ortstein, and ordinary sandy soil are given, which 

 illustrate clearly the process doscribe<l. 



Role of mica in cultivated soil, BiKLiu-CnATELAN (Compt. Rend. Acad. Sci. 

 [Paris], 150 (1910), No. 18, pp. 1132-1135; abs. in Jour. Soc. Chem. Indus.. 29 

 (1910), No. 11, p. 709; Chem. Ahs., .', (1910), No. Iff, pp. 1885, 1886; Rev. Sci. 



