RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY. 



On the free acids in mineral and bone superphosphates, A. Quabtaroli 

 and (J. Masoni {Sfaz. Sikt. Ai/i: Hal.. .IS (]!)().')). \(k ')-(!, pp. Ji92-502; ahs. in 

 Cliciii. Cciifhl.. lUi).'). II, \(). I.i. pp. 'JS',. US.')). — To detenuine free acids the 

 authors shake ui» 2't ,mii. of iiiatci'ial with 250 cc. of water for a few minutes, 

 filter (luiekly throu.srh a fohh'd filter, and titrate 50 cc. of the filtrate diluted to 

 ;;(I0 ec. with one-half normal sodium hydroxid and methyl oranije. Of 100 min- 

 eral superphosphates thus examined the majority eontained from 5.29 to 10.98 

 jier cent of free acids reckoned as phosphoric acid, a few contained as low as 2.G 

 per cent. The hone su])erphosphates seldom contained over 2.5 per cent of fi'ee 

 a<ids. The presence of larger amounts. 5 to G per cent, indicated adulteration 

 \\ ith mineral superphosphate. To further aid in the detection of adulteration 

 the authors determined the constants for inversion of saccharose hy the t'.vo 

 >uperphosphates, hy phosphoric acid, and by sulphuric acid, by treating 1 gm. 

 of pure saccharose for 6 to 12 liours at 25° C. with 30 cc. of thirtieth-normal 

 solution of these substances and determining the inverted sugar hy the Fehling 

 method. These constants, with the results of the titration for free acid and of 

 a i)hysical examination, are thought to furnish reliable means of detection of 

 adulteration of hone superphosi)liate by mineral superphosphate. 



Free acid in superphosphate, L. Schucht (Ztsclir. Angew. Chcm., 18 

 (1911.')). pp. 1020-102.}; ahs. in .lour. Choii. I^oc. {Loiuloti]. 88 (190.5), No. 51.~>, 

 II. I). (ilO). — Five gm. of the superphosjibate is extracted 10 times with ace- 

 tone, ushig in all about 75 cc. of the solvent. The turbid solution obtained is 

 cleared up with 200 cc. of water, a little sodium oxalate and sodium chlorid are 

 added, tlie solution filtered if necessary, and the free acid is titrated with half- 

 normal alkali, using methyl orange as indicator; 



The oxidation of nitrous acid by means of hydrogen peroxid; determina- 

 tion of nitrates in presence of nitrites, M. Blsch (Bcr. Deitt. Cliciii. GchcU., 

 39 (1906). No. 6, pp. lJ,01-l.',0.i ; ah.s. in Cheni. Cciilhl.. 1:106. I. No. 21. p. 167.')). — 

 The author found in experiments with nitro-cellulose that the use of a 3 per 

 cent neutral solution of hydrogen peroxid is a convenient means of (piantita- 

 tively oxidizing nitrous acid to nitric acid. In a solution containing both 

 nitrous and nitric acids, nitrous acid is first determined in one portion by titration 

 with permanganate, then in another portion of the solution the nitrous acid is 

 oxidized with hj-drogen peroxid to nitric acid and determined by means of nitron 

 (E. S. R.. If), p. 945). 



Examination of water, W. P. Ma.son (Neiv York: .lohii Wilnj cC- Son, 

 1906. .1 rtl.. rcr., pp. l.'t.'>. pU. .J. /?r/-s-. //). 



Contribution to the determination of nitric acid in water, P. Drawe 

 {Clirni. Ztff.. 30 (1906), No. J/S, pp. o30. .')S1).—A modification of Frerichs' 

 method (E. S. R., 14, p. 940) is described and recommended. 



Modern methods of testing milk and milk products, L. L. Van Slyke 

 (New York: Oraiiiic .linUl Co.; Lo)tiIo)i: K. Paul, Trench, Trilhner & Co., Ltd., 



0579— No. 1— UU 2 7 



