SOILS FERTILIZEES. 419 



Soil classifications and adaptations, J. L. Hills, C. H. Jones, and P. A. 

 Benedict (Tcrmont Hia. Bill. 15'/, pp. 703-743). — This article discusses the 

 four principal soil classiflcutions which have been proposed, as follows: (1) 

 That developed by Merrill and based upon the origin and method of formation 

 of the soil, (2) that based upon physical characteristics of the soil, (3) that 

 suggested by Snyder and based mainly upon the use to which soils are put, and 

 (■i) that employed by the Bureau of Soils of this Department and based upon 

 its soil surveys In different parts of the United States. Soil adaptations are 

 discussed in their relations to size of soil particles and methods of soil forma- 

 tion and deiwsition, as well as on the basis of personal observations in the 

 course of soil surveys. A glossary of technical terms and a list of the principal 

 authorities consulted are given. 



Physical analysis of soils, E. A. Mitscherlich (Ztschr. Angeiv. Chem., 23 

 (1910). No. 39, pp. 1SJ,0, 1841, fig. 1; Chem. Ztg., 34 {1910), No. 113, pp. 1000, 

 1007; ahs. in Jour. 8oc. Chem. Indus., 29 (1910), No. 20, p. 1217).— It is stated 

 that in determining the size of soil particles the mechanical analysis by the 

 sieve and sedimentation method has given no positive results because it does 

 not account for the differences in form, in specific gravity, and in colloidal 

 structure of the soil particles. For similar x'easons microscopic examination 

 does not serve the purpose. As determined by the author's method the soil 

 surface furnishes a measure of the fineness of the soil type, without, as is the 

 case in the sieve and sedimentation method, presupposing a definite form and 

 the same specific gravity of the soil particles. 



In his method the author distinguishes between the outer and the inner sur- 

 face of the soil, both being wetted with water but only the outer one with 

 organic liquids of high molecular weight. 



To determine the hygroscopicity and the outer soil surface the air-dried soil 

 is exposed over 10 per cent sulphuric acid in a vacuum desiccator and after 

 vapor tension equilibrium weighed, then dried for 4 hours over phosphoric 

 finhydrid at 100° C. and weighed, and finally placed over a 15 to 25 per cent 

 benzol oil mixture and after vapor tension equilibrium again weighed. The 

 first weighing after deducting the weight of the dry soil (second weighing) 

 gives the total soil surface (hygroscopicity) in percentage of the dry soil. The 

 last weighing multiplied by 3.S6 gives the outer soil surface. The total surface 

 is a measure of the productivity, while the outer surface relates to the mechan- 

 ical state of the soil and is indicative of the ease of working. 



A series of pot experiments with mustard on a mixture of sand with varying 

 quantities of peat was made to show the relation between the yield and the 

 total surface or hygroscopicity as determined by the above method. From the 

 results obtained the author deduces the following equation for determining the 

 relation between yield (?/) and hygroscopicity (j^) : log ((50 — 2/) =1.4 — l/24a?. 



The niech.anical analysis of soils in Buitenzorg', Java, E. C. J. Mohr (Bui. 

 Dept. Agr. Indes N6erlmid., 1910, No. 41, pp. 33, pi. 1; Teysmarmia, 21 (1910), 

 No. 7, pp. 455-471, pis. 3). — The author calls attention to the fact that on 

 account of the rapid changes which go on in soils in tropical countries like Java 

 mechanical analysis at any given time is of less value than in case of soils of 

 temperate regions. It is more necessary in the former case to follow closely 

 the changes going on in the soil. 



The methods used (based to a large extent upon those of the Bureau of Soils 

 of this Department) are described as well as methods of stating and interpret- 

 ing the results. Classification by means of an equilateral triangle, the three 

 points of which are sand >50/a, dust 50-5ja, and finest particles <C5fi, is ex- 

 plained. The author is of the opinion that determination of hygroscopicity by 



