RECENT WORK l\ AGRICULTURAL SCIEN! E. 



AGRICULTURAL CHEMISTRY. 



Methods of titration of phosphoric acid, < >. .1. 1 1 i.aynh k \ | Ztschr. Angi u . ' 'hi m., 

 t8(1905)"i pp. 65.5, 656; abs. in Analyst, SO [1905), No.852, pp. 257, 258).— The author 

 describes what he considers to be a simple and practical modification of Hundeshagi 

 method. The phosphoric acid is precipitated as magnesium-ammonium phosphate 

 by the citrate method, the precipitate collected on a hardened filter paper, washed 

 firsl with -■■ per cenl ammonia and then with alcohol until free from ammonia, the 

 total volume of the washings nol exceeding about 40 cc. "The precipitate is then 

 washed off with cold water into a porcelain dish I total volume required about 200 cc. , 

 and, after the addition of a few drops of methyl orange solution (strength, 0.1 per 

 cenl i, decomposed with aslight excess of ^-normal HC1, and the excess found by 

 titration with , -normal NaOH (1 CC. f,, -normal acid=0.01065 gin. P a O 



A rapid volumetric method for the determination of phosphoric acid, 

 W. B. Hikt and F. W. Steel (Proc. Soc. Chem. Indus. Victoria, 1905, Mar.-Apr.; 

 Chem. News, 92(1905), No. 2889, pp. 113, 114). — A slight modification of Littmann's 

 method E. S. R., 10, p. 513) is described and recommended as preferable to Pem- 

 berton's method Eor < imercial work. 



Solubility of lime and magnesia in solutions of sodium chlorid with or 

 without sodium hydroxid. — Application to the separation and estimation 

 of the two substances, E. Maigbet (Bui. Soc. Chim. Pari*, 8. set., 33 I 1905), A 

 11, pp. 631-684, figs. .': abs. in Jour. Chem. Soc. [London'], 88 (1905), No. 513, II. p. 

 -The author makes use of the fact that while lime is fairly soluble, magnesia 

 is insoluble in solutions containing less than 160 gm. per liter of sodium chlorid in 

 presence of 0.8 gm. per liter of sodium hydroxid in extending and making more 

 accurate lyAnselme's method of estimating lime and magnesia. 



Th.- method proposed by the author is as follows: To 100 cc. of the solution in a 

 200 cc. flask add 20 cc. of a solution containing sodium carbonate, 100 gm., and 

 Bodium hydroxid, 20 gm., per liter, the equivalent of which in 2-normal hydro- 

 chloric acid is known. Heat the mixture to boiling, cool, and makeup to 200 CC 

 with a solution of sodium chlorid, L60 gm. per liter. Shake the mixture, tilter. and 

 titrate 100 cc of the filtrate with 2-normal hydrochloric acid, using tropeolin as 

 indicator. The difference between twice the burette reading and the equivalent of 

 the alkaline solution added gives the total magnesia and lime present in terms of 

 2-normal hydrochloric acid. 



To determine magnesia alone add to 100 CC. of the solution L0 CC. of a solution of 



sodium hydroxid, 80 gm. per liter; dilute to 1 liter with a solution of sodium chlorid. 

 160 gm. per liter; shake, filter, and titrate 500 cc of the filtrate with 2-normal 

 hydrochloric acid, using phenolphthalein as indicator. The difference between the 

 burette reading multiplied by 2 and the amount of sodium-hydroxid solution added 

 gives the magnesia present. The difference between this and the first determination 

 gives the lime present. 



On the determination of nitrogen by the Kjeldahl method, 8. P. 1. 8 

 sen, C. Pedebsen, and A. C. Anderson [Compt. Rend. Lab. Qarlsberg, , No. 



333 



