SOILS — FERTILIZERS. 947 



Studies of the effect of heating the Boil on the solubility of the phosphoric acid 

 showed thai samples of peat which in their natural condition did n< >t contain 

 determinable amounts of phosphoric acid soluble in ammonium humate yielded 

 0.006 to 0.061 per cenl when heated at L60 I '. 



The removal of soluble salts from soils, M. Ring elm ann (Jour. Agr. Prat., n. 



ter., li [1906), No. 6, />/>. /; ;. 175). Methods of il ling and drainage employed 



for this purpose in Egypt are briefly described. 



Progressive changes in soil moisture, \Y. ■ rOTZ < Met. Ztschr., No. I. 



pp. / ; 24) > 1 1 is maintained in this article thai in the course ol centuries there has 

 been a progressive draining away of the moisture from the upper layers of the Boil, 

 ('specially of the higher lands, a reduction "t" the humidity of the air, and consequent 

 increase in temperature variations between seasons and between nighl and day. 



Underground studies, C. Ochsenius (Helios, 22(1905), pp. ■ '.'. 66 Accounts 

 are here given of studies of underground conditions in the region of Venice and of 

 Frankfurt, the fust with especial reference to the sinking of the soil, resulting in 

 the tall of the ( 'am | .anile, ami the second with reference to the occurrence of Ball 

 deposit-. The order of occurrence of the salt deposits I especially potash salts) under 

 Frankfurt, their extent, composition, and uses, are discussed. 



Soil physics laboratory guide, \Y. II. Stevenson and I. < >. Schadb (New York: 

 Orange Judd Co., 1905, pp. 80, pi. I, figs. 16).— This hook, which is the outgrowth of 

 the laboratory-instruction given at the Iowa Agricultural College, is designed "to 

 present to" the instructor and the student a carefully outlined series of experiments 

 in soil physics." It includes a series of 40 exercises accompanied by questions on 

 various features of the experiments outlined. 



"An earnest efforl has been made to outline the exercises briefly and clearly in 

 older that the student may proceed with the work without loss of time and without 

 confusion. The exercises are also listed in a logical order with reference to their 

 relation to each other and the skill required <>n the part of the student." The book 

 is an extension of a pamphlet on the same subjeel issued by the department of 

 agronomy of the Iowa Agricultural College. It meets in a very satisfactory manner 

 a widespread ami growing demand for a simple text-book on the subject. 



Economic geology of the United States, II. Ries (New York and London: Thi 

 MacmUlan <'<>., 1905, pp. XXI /•<'•<, />/•-•. 25, figs. 97). — It is state.) that this work 

 covers essentially the ground which is gone over in the elementary course in this 

 BUDJecl at Cornell University, and it is hoped that it will prove useful as a text-book 

 in other colleges. The arrangemenl differs from that of other hooks on the same 

 Bubject in that the nonmetallic mineral- are discussed first and the metallic minerals 

 last, the reason for this being that the non-metallic mineral- are much more impor- 

 tant and valuable than the metallic and because it leads from a discus-ion of the sim- 

 pler to the more complex forms of mineral deposits. 



The hook contains chapters on coal; petroleum, natural gas, and other hydrocar- 

 bons; building stones; clay; lime and calcareous cement-: salines; gypsum; fertilizers: 

 abrasives; minor minerals; water; -oils and road materials; ore deposits; iron; copper; 

 lead and zinc; gold and silver; Bilver-lead; aluminum, manganese, and mercurj ; and 

 minor metals. At the end of each chapter there is a selected list of paper- relating 

 to the Bubjecl discussed. 



The statistical data are drawn mainly from the reports of the l". S. Geological Sur- 

 vey. The chapter on fertilizers deals with the occurrence, nature, and u<es of phos- 

 phate-, guano, and greensand. The chapter on soils and road materials discusses 

 the origin and properties of soils, especially residual and transported soil.-, and the 

 distribution of soils in the Tinted States, and very briefly considers the various 

 available road materials in the United States. 



Nitrification of nitrogenous matter in the soil, (*. Mason] i Atti /.'. Accad. Econ. 

 Agr. Georg. Fireme, 5. wr., 1 (1904), No. J-->, pp. £66-869; abs. in Centbl. Bald, [ete.], 



