AGRICULTURAL CHEMISTRY. 1009 



discussed, and tlio followini,' iiiotliod of tcsCmjx for acidity iUw to such acids is 

 described : 



To 100 CO. of a water solution of 2 jj;m. of potassium iodid and 0.1 jjui. of 

 potassium iodate add 1 gm. of the soil in case of peaty soils, but a larger 

 amount in case of mineral soils. Allow the mixture to staud with frequent 

 shaking for ] hour, and filter. Test for iodin set free by the organic acids by 

 adding a few drops of the filtrate to a dilute starch solution. For exact deter- 

 miiation of the free acids the authors refer to a simple oudiometric method 

 described by one of thi'ni sexcral years ago. 



An improved method of determining acidity in soils, II. Hucutino (Zl-sclir. 

 Angew. Chan., 21 (li)OS), A'o. .'/, pp. 151-153; abs. in Chem. Zenthl., 1908, I, No. 

 8, p. 760; Analyst, 33 (1908), A'o. 385, p. I.'i2; Jour. CJicin. Soc. [London], 9.', 

 (1908), No. 5J,5, II, pp. 231, 232; Bui. Soc. Chim. France, J,, scr., .'/ (1908), No. 8, 

 p. 610). — The method described is a modification of Tacke's method which is 

 based upon the decomposition of calcium carbonate when mixed with acid soils 

 (E. S. R., 9, p. 32). 



In the method described 10 to 30 gm. of humus soil, or 30 to 50 gm. of 

 mineral soil, is mixed with water and a moderate excess of calcium carbonate. 

 The carbon dioxid evolved is removed with a stream of hydrogen, .50 cc. of 20 

 per cent hydrochloric acid is then added, and the carbon dioxid thus set free 

 from the calcium carbonate not previously decomposed by the soil acids is col- 

 lected in standard solution of caustic «oda aud determined by titration in the 

 usual manner. 



Eliminating' the citric acid from the soil solution (Intcrnat. Sttf/ar Jour., 

 10 (1908), No. 110, pp. 59, 60).— The method which has been worked out in the 

 laboratory of the sugar experiment station at Lima, Peru, is as follows: 



" To the 750 cc. of the filtered solution which contains iron, potash, lime, etc., 

 add a few drops (2 or 3 cc.) of HNO3; evaporate to a volume of about 100 cc. 

 Transfer the evaporated solution to a 200 cc. Kjeldahl digestion flask used for 

 the nitrogen determination, and continue the evaporation in this flask until the 

 solution is reduced to 50 or 75 cc. Add 30 or 40 cc. of strong HNO3, continue 

 the boiling and evajiorating until reddish fumes are given off and then boil 5 

 or 10 minutes longer. Kemove the flask, transfer the contents to a small 

 evai)orating dish, add a little HCl (3 or 4 cc), evaporate to dryness. If the 

 operation is carefully conducted there will be no citric acid remaining. The 

 work from this point is continued in the regular manner."' 



The volatilization of certain mineral elements in ashing plant materials, 

 W. W. Skinner (Ahs. in Science, n. scr., 27 (1908), No. 686, p. 296).— This is 

 an abstract of a paper presented at the Chicago meeting of the American Chem- 

 ical Society. This paper gives results of studies on the loss of sulphur when 

 orgrnic substances are ashed by the ordinary method as compared with the 

 sulphur obtained by the peroxid and combustion in oxygen methods. "Analyses 

 are given of 2 samples of cotton-seed meal, 2 samples of nuistard-seed meal, 

 3 samples of malt, 4 samples of barley, and 3 samples of wheat. The loss of 

 sulphur varied from 81) per cent to 07 per cent." 



A simple method for estimating calcium in organic materials, II. Aron 

 (Biochem. Ztschr., Jf (1907), No. 2-3, pp. 268-270).— \\\ the method described 

 organic matter is destroyed with nitric and sul|)huric acid and the calcium 

 which then exists as sulithate is precii>ilated with absolute .-ilcohol and weighed. 

 As the author points out, the method can not be thus uswl if barium or stron- 

 tium is present. 



Measurement of citral in species of lemon grass, A. Hi.ocir (/>/</. I'Jcon. 

 Indo-Chine, n. acr., 10 (1907), No. 67, pp. 78J-788). — The author concludes from 



