1046 EXPERIMENT STATION RECORD. 



sugar and ammonium sulphate solutions supplied. Three per cent grape-sugar solu- 

 tion was found to be too strong for Urobacillus pasleuri. 



Experiments with. CDpper-iron sulphate for water purification at Marietta, 

 Ohio (Engin. Rec, '3 (1906), Xo. 12, pp. 392-394, figs. 4)-— The successful use of 

 a mixture of copper and iron sulphates precipitated with caustic lime and held on 

 the filter for precipitation of impurities and reduction of the number of bacteria in 

 water is reported. 



SOILS— FERTILIZERS. 



Soils, T. Dietrich and F. Honcamp (Jahresber. Agr. Chem., 3. ser., 7 (1904), pp. 

 25-99). — A review is given of the literature relating to this subject published during 

 1904, classified as follows: Rocks, stones, and their weathering products; cultivated 

 soils, including analyses of soils, physics of soils and absorption, and the lower organ- 

 isms of soils; and moors and moor culture. 



Mechanical analysis of soils, J. A. Murray (Chem. Xeics, 93 (1906), Xo. 2409, 

 pp. 40-42; abs. in Analyst, 31 (1906), Xo. 361, pp. 129, 130).— This article describes 

 " a long tube sedimentation process." 



The apparatus employed consisted of an Erlenmeyer flask (of about 200 cc. capac- 

 ity) of which the neck, after removal of the flange, was exactly the same diameter 

 as a long glass tube which was attached to it by means of a piece of india-rubber 

 tubing fitted outside of the tube and of the neck of the flask. The tube actually 

 used was 147 cm. long by 2.3 cm. internal diameter. "A wide shallow glass basin 

 about 20 cm. diameter and a few small porcelain evaporating dishes about 7.5 cm. 

 diameter are also necessary. . . . 



"The experiment was carried out as follows: Five gm. of the air-dried fine soil 

 (i. e., that which had passed through 100-mesh sieve), thoroughly disintegrated in 

 dilute ammonia solution, was put into the flask, which was then vigorously shaken, 

 filled nearly full of water, and attached to the tube. Water was then poured gently 

 down the side of the tube (so as not to disturb the sediment in the flask) till it also 

 was full, when the open end was closed with a cork, and the whole inverted over 

 the large basin of water. The cork closing the end was immediately withdrawn, 

 and one of the small porcelain evaporating dishes, previously dried and weighed, 

 placed beneath the open end of the tube. 



''The sediment began to descend whenever the tube was inverted, and the first 

 particles were deposited in the dish in about fifteen seconds. After a short interval 

 this dish, containing the first portion, was removed and replaced by another, and 

 this again by a third, and so on. These dishes containing the several fractions of 

 the sediment thus removed from the large basin were of course full of water, of 

 which, however, a considerable part was separated by simple decantation, after 

 standing for a few minutes, and the remainder driven off on the water bath. The 

 dried residue was then weighed, and examined under the microscope for determina- 

 tion of the size of the particles." 



Results of tests of the method on a sample of stiff clay soil and of Rothamsted soil 

 are reported. 



It was found advisable in case of the heavier soil to make a preliminary rough 

 separation of the finer and coarser material by shaking with weak ammonia, allow- 

 ing to stand 15 minutes, and pouring off the solution containing the fine material in 

 suspension. The coarser material was introduced into the apparatus described and 

 separated into 3 fractions, viz, those separating in 5, 15, and 40 minutes after the 

 beginning of the test. Preliminary separation was not necessary in case of the 

 lighter Rothamsted soil. 



A chemical study of some Oregon beaver-dam soils, C. E. Bradley (Jour. 

 Amer. Chem. Soc, 28 (1906), Xo. 1, pp. 64, 65). — Analyses of 5 samples of beaver-dam 



