520 EXPERIMENT STATION RECORD. [Vol.37 



condition, to a suppression of some toxic material, or to a development of acids 

 from the action of the antiseptics. The method of applying the antiseptics 

 seems to have no marked influence upon the results obtained. The closely 

 coordinated stimulation of plant and bacterial activity due to the treatment 

 of the soil with volatile antiseptics points strongly toward a biological 

 interpretation, with due regard for the chemical considerations, of the effects 

 therefrom." 



Farms, forests, and erosion, S. T. Dana {U. S. Dept. Agr. Yearbook 1916, pp. 

 107-134, pis. 10). — This article gives data on the injury to farm lands and agri- 

 cultural and other industries of the United States resulting from erosion, floods, 

 and washing. A direct relation between these and deforestation of the higher 

 areas is shown. 



It is concluded that " the problem of erosion and its control forms an integral 

 part of any comprehensive plan for the development of our natural resources. 

 If all land were put to its best use and so handled as to maintain its produc- 

 tivity the problem would be solved. This result can be attained, however, only 

 by marked change in our present practice. A stop must be put to reckless de- 

 struction of the forest, to uncontrolled fires, to overgrazing, and to careless 

 farming. For the sake of the fanner in particular and the public in general, 

 steps should be taken to retain and restore the forest cover in the mountains 

 under public ownership or supervision. There should be brought home to the 

 people as a whole the extent and seriousness of erosion and the necessity- for its 

 control by the comnmnity." 



Measuring the surface temperature of soil, A. A. Dobiasha (Dobiache) 

 {Zap. Selsk. Khoz. Inst. Imp. Petra I (ilcni. Itist. Agron. Emp. Pierre I), 1 

 (1916), pp. 101, 102, pi. 1). — Methods of surface soil temperature measurements 

 used In 30 years' experiments in Russia are described and compare<l. The 

 methods of slightly pushing the thermometer into the surface soil or of placing 

 it on the surface and covering it wth soil were found to give inaccurate 

 lesults. 



In a third method three thermoelements on ebonite supports and made of 

 thin wire were place<J one below the other at equal distances of 1.5 mm. and 

 covered with soil so that the upper one remained visible. Three mercury 

 thermometers covered with soil and three open thermometers were placed 

 parallel to the thermoelements. The day of test was hot and sunny and the 

 temperature of the surface layer reached 60* C. 



It was found that the mercury thermometers covered with soil showed a 

 mean temperature some 2.4° higher than the uncovered ones. The tliermo- 

 elcmenls acted difTercntly, the upper one showing the highest temperature and 

 the difference reaching in some cases 5°. The temperature of the upper element 

 reacted promptly to changes in temperature due to the passing f»f clouds before 

 the sun. Only at deptlis of from 1.5 to 2 mm. were the temperatures recorded 

 equal to that of tlie covered thermometer. It is concluded that the latter 

 gives more accurate results, but that during strong radiation none gives trust- 

 worthy results. 



Studies on soil colloids. — II, Influence of colloids on electrical conductivity 

 of salts, RI. I. WoLKOKK (Soil Set.. S (1017), Xo. 5, pp. 423-430, figs. ^').— i:xi)cri- 

 ments conducted at Uiitgers College are rep( rtod in which fiftli-nornial solu- 

 tions of aluminum potassium sulphate, ferric sulphate, lead nitrate, and hydro- 

 chloric acid and a .snturated solution of calcium hydroxid were added to a 

 colloidal solution obtained from a fresh clay soil. 



It was found that " the inorganic colloid particles, as found in clay, especially 

 the colloidal gels, hinder the electrical conductivity of salt solutions. The 

 causes for sucii an interference lie pos&ibly in (1) the fact that colloidal 



