CHEMISTRY. 319 



author recommends that in the precipitation with molybdic solution the beakers be 

 allowed to stand 10 to 15 minutes in a water bath which is not liigher than S0° C. at 

 the beginning and is allowed to cool after the beakers are placed in it. 



Estimation of phosphates in potable waters, A. G. Woodman and L. L. Cayvan 

 {Juiu: Aiiirr. Chan. Sur., ..'.] [lUOl), X<,. .?, },p. !H!-107, fign. f).— The ordinary colori- 

 metric methods are criticise<l and the following modification is recommended: ^lix 

 50 cc. of the sample with 3 cc. of nitric acid (sp. gr. 1.07), evaporate to dryness on a 

 water bath, and dry the residue in a water oven for 2 hours to render silica insoluble. 

 Dissolve in 50 cc. of water, and without filtering introduce into tube for colorimetric 

 determination. Tubes of hard white glass 2.5 cm. in diameter and 24 cm. long to 

 the 100 cc. mark are recommended. To the solution in these tubes add 4 cc. of 

 ammonium molybdate solution (50 gm. per liter) and 2 cc. of nitric acid (sp. gr. 

 1.07), and after ,3 minutes compare the color with that obtained ]>y the use of 

 standard solutions oi sodium phosphate. 



On the determination of dry matter in soil samples, H. Pichner (LdixJir. 

 Vers. Stiii., 55 {1901), Xo. 4-5, jij>. 300-324) ■ — Determinations of moisture in a large 

 number of different kinds of soils, using various kinds of appai'atus and methods, are 

 reported. From the results obtained the conclusion is drawn that it is impossible to 

 accurately determine moisture in soils by means of the ordinary methods of drying 

 at 105° C. The precautions which the author suggests in order to secure accuracy 

 are (1) cooling the dried sample only in a closed desiccator before weighing; (2) the 

 use of a well-ventilated drying oven, so that the heated gases are rapidly removed; 

 (3) the introduction of the sample ir^o the drying bath only after the temperature 

 has been raised to 105°, and (4) maintaining the temperature uniformly at 105°. 

 The apparatus which the author considers most nearly satisfying these conditions 

 are those of Soxhlet^ and Ulsch.^ It is suggested that electrical heating might be 

 applied to this purpose with advantage. 



Calcium carbonate in soils, and a ne^w^ apparatus for the determination of 

 the same by practical agriculturists, M. Passox {Dciit. Landir. Presse, 28 {1901), 

 No. 4~, PP- 367, 368, fif). 1). — The importance and function of active lime compounds 

 (carbonates) in soils are discussed, and a modification of Gerlach's simplified Rcheib- 

 ler apparatus for the rapid determination of carbonates in soils is described. This 

 apparatus consists of two parts, a generator and a measuring tube. The generator 

 consists of a wide-necked glass flask, closed with a rul)l)er stopper, through which 

 passes the small neck of a pear-shaped flask, which reaches down into the larger flask 

 and carries the hydrochloric acid used in driving off the carbonic acid from the soil. 

 This smaller flask has a hole in its side through which the acid is introduced. The 

 measuring tube is U-shaped, about 2 cm. in diameter, and 20 cm. high. The right 

 arm is funnel-shaped at the top and has a side tube w'ith stopcock near the bottom. 

 The left arm carries a scale covering a volume of 4.65 cm., graduated to read to tenths 

 of a per cent of calcium carbonate. This tube is connected wdth the genei'ator by 

 means of a rubber tube. In operation, the tube is filled with w^ater to the zero mark 

 of the scale. The small jiear-shaped flask of the generator is filled about three- 

 fourths full with dilute hydrochloric acid through the hole in its side. About 20 gm. 

 of the soil to be tested is placed in the larger flask of the generator. The parts of the 

 apparatus are then connected, and the generation of the carbon dioxid from the soil 

 is begun by tilting the digestion flask so that the acid runs out of the hole in the side 

 of the small flask upon the soil. The gas passes over into the measuring tube, dis- 

 placing the water in the left arm and causing it to rise in the right. By means of 

 the stopcock the level of the water is maintained at the same height in ])oth arms of 

 the tube. When no further gas is evolved by vigorous shaking of the generator, the 



'Ztschr. Angew. Chem., 1891, p. 363. 

 H.hem. Ztg., 19 (1895), No. 51, p. 1183. 



