418 EXPERIMENT STATION RECORD. 



The determination of phosphoric acid in soils as ammonium phospho- 

 molybdate by means of the centrifuge, E. Gullv {('hem. Ztg., 25 [1901], No. 39, 

 pp. 419-421; abs. in Chem. Centbl. 1901, I, No. 35, p. lS42).—T\\\s article reports tests 

 by A. Baumann of the applicability of the Gotz method described by Wedding^ to 

 the determination of phosphoric acid in soils. The essential features of the method 

 are the precipitation of the phosphoric acid as ammonium phosphomolybdate in a 

 graduated centrifuge cylinder; the separation of the precipitate by 4 minutes centri- 

 fugating at the rate of 1,100 to 1,200 revolutions per minute; and the reading of the 

 volume occupied by the precipitate and calculating the results. A satisfactory agree- 

 ment of the results by this method and by the gravimetric method in case of 63 

 samples of soil is reported. 



A claim of priority regarding the determination of phosphates in pota- 

 ble waters, C. Lepierre {Bul.Soc. Chem. Paris,3.ser.,25 {1901), No. 16-17, p. 800). — 

 The author states that the method recently described by Woodman and Cayvan 

 (E. S. R., 13, p. 319) is exactly the same as that described by him in a communica- 

 tion to the second International Congress of Applied Chemistry in 1896 (E. S. R., 

 10, p. 16). 



Determination of calcium and magnesium in natural vraters, L. W. Winkler 

 {Ztschr. Analyl. Chem., 40 {1901), pp. 82-92; abs. in Jour. Chem. Soc. {^Londori], 80 

 {1901), No. 463, II, p. 347). 



The determination of ammonia, nitric, and nitrous acids in natural waters, 

 L. W. Winkler {Chem. Ztg., 25 {1901), No. 55, pp. 586, 587).— Tha methods used 

 by the author are given in detail, being a revision of methods previously described.^ 



Determination of dissolved oxygen in waters in presence of nitrites and of 

 organic matter, S. Rideal and C. G. Stewart {Analyst, 26 {1901), No. 303, pp. 

 141-148; abs. in Chem. Centbl. 1901, II, No. 3, p. 232). — A series of tests are reported 

 which, in the authors' opinion, show that by their modified Winkler process — 

 oxidizing with permanganate in acid solution, out of contact with air, in ordinary 

 stoppered bottles of known capacity, adding soda and potassium iodid solution and 

 determining the liberated iodin with thiosulphate and starch — it is possible to ascer- 

 tain with accuracy the amount of free oxygen rapidly in highly colored and polluted 

 field waters. 



An improved method for the rapid estimation of sugar in beets, R. S. Hilt- 

 ner and R. W. Thatcher {Nebraska Sta. Rpt. 1900, pp. 49-69). — Attention is called 

 to the need in plant breeding, and also in factory operations, of a rapid method for 

 estimating the sugar in beets. Present methods give satisfactory results, but are 

 liable to certain errors which increase with more rapid manipulation. The authors 

 propose a modified method which they have found to give very accurate results. 

 The factors used are those required by the Schmidt and Haensch polariscope, al- 

 though other instruments may be used by changing the factors accordingly. 



While all beets do not contain the same percentage of water, it does not vary 

 within very wide limits. In a long series of determinations made at the Nebraska 

 Station during several years, the water content in nearly all cases varied between 80 

 and 84.5 per cent. From these results the authors state that it is possible to assume 

 an average factor which would not vary from the true amount of water above 2 per 

 cent, except in very rare cases. This maximum of error will not change the dilution 

 of the sugar solution enough to create any appreciable difference in the polariscope 

 reading. The method of determining the water content of the beets is given, and 

 from an average assumed factor the authors construct a table showing, at a glance, 

 the desired volume of water to be added in analysis. In carrying out this method 



iStahl und Eisen, 7 (1887), p. 118. 

 ='Chem. Ztg., 23 (1899), p. 454. 



