soils. 34 f) 



The data regarding the chemical composition show that in the mechanical fractions 

 of both the loess and podzol the amount of silica decreased and the other chemical 

 constituents (alumina, ferric oxidj lime, magnesia, etc. i increased as the size of the 

 particles decreased. The data further showed that all the mechanical products of the 

 loess were richer as regards chemical composition than the corresponding products 

 of the podzol, which fact is the more important as the quantity <>f the very small par- 

 ticles in the loess (24.85 per cent 1 ) considerably exceeds that in the podzol (3 to 5 

 per cent). 



The specific gravity of the loess itself and of its mechanical fractions is greater than 

 in the case of podzol. In both the soils the specific gravity of the mechanical frac- 

 tions increased as the size of the particles decreased. To gain an idea of the volume- 

 weight, compactness, and porosity, the author made briquettes from the separate 

 mechanical fractions which were weighed and measured before and after drying. It 

 was found that as the size of the particles decreased the quantity of the water evapo- 

 rated from the briquettes increased, while the volume diminished, the decrease in 

 volume being greatest in the products of the loess. The data showed that the volume- 

 weight of the mechanical fractions of the loess increased as the size of the particles 

 diminished, while in those of the podzol the contrary holds, except in the case of the 

 finest particles (clay). The 1< less and its mechanical products showed a larger volume- 

 weight than the podzol and its products. The porosity of the separate mechanical 

 products was inversely as their volume-weights. Thus, in the loess the porosity 

 diminished with the decrease in the size of the particles, while in the podzol it 

 increased with the decrease in the size of the particles down to the finest particles, 

 which showed a small relative porosity. 



These differences in the properties of the mechanical fractions of the loess and 

 podzol are accounted for, in the opinion of the author, by the difference in the form 

 of the particles. In the loess and its mechanical products flat and scaly particles 

 predominate, while in the podzol and its mechanical products, the clay excepted, 

 spherical particles of quartz predominate. Flat particles are more easily wetted and 

 ] m issess a greater power of cohesion, thus causing greater compactness ( volume-weight) 

 and less porosity. — p. fireman. 



Experiments on the relative fertility of soil particles of different grades, 

 D. L. Rudzinskx (Izv. Moscow Selsk. Khoz. Inst. [Ann. Inxt. Agron. Moscow], 9 (1903), 

 No. 2, pp. 172-234, pis. 5). — The author prepared large quantities of the different 

 sizes of soil particles for use in his experiments by means of the Fadyeyev-TVilliams 

 method, which is as follows: 



One kilogram of the air-dry soil is sifted through a sieve with holes 3 mm. in 

 diameter. The lumps which do not pass through the sieve are disintegrated by 

 rubbing in a mortar with a rubber-tipped or wooden pestle and again sifted. From 

 the part of the soil which contains no particles larger than 3 mm. an average sample 

 weighing 100 gm. is selected, while the part remaining on the sieve is freed from the 

 finer grains clinging to it by boiling with water in a dish and then washing with 

 pure water. The washed coarse grains are dried, sorted by sieves with holes of 10 

 and 5 mm. in diameter, and weighed. 



A part of the sample, with particles not exceeding 3 mm. in diameter, is boiled with 

 water for 6 hours in an enameled iron dish covered with a watch glass, allowed to 

 cool, and washed into a sieve with holes 0.25 mm. in diameter placed in a large 

 porcelain dish. The particles remaining on the sieve after pressing with a rubber- 

 tipped glass rod and washing, are dried at 100 to 110°, again sifted, and then sorted 

 by means of 1 mm. and 0.5 mm. sieves into 3 grades: Coarse sand with particles 1 to 

 3 mm., medium sand, 1 to 0.5 mm., and fine sand, 0.5 to 0.25 mm. in diameter. Each 

 of the grades is dried at 100 to 110° and weighed. 



