RECliNT WORK IN AGRirUI.TURAL SCIENCE. 



CHEMISTRY. 



Determination of phosphoric acid available as plant food in 

 soils and fertilizers, .1. Plot {Oesterr. Chem. Ztg., J {1900), pp. 

 127-l.U: ills, ht Jour. ('hem. Soe. [London], 78 {1900), No. 1^53, IL 

 p. 510; J<nifr. Soe. Chem. Ind., 19 {1900), JVo. 7, p. 676).— The. solvent 

 used by the author is claimed to resemble closely T)eet juice in respect 

 to salts, and is prepared as follows: Dissolve 0.4004 gm. of ferrous 

 sulphate. 1.4616 gm. of potassium sulphate, 3.7098 gm. of calcium 

 nitrate, and 2.890 gm. of magnesium chlorid in 1 liter of water. Fuse 

 7.0566 gm. of crj'stallized sodium carbonate, 6.744 gm. of potassium 

 carbonate, and 0.2 gm. of silicic acid in a platinum crucible, dissolve 

 the fused mass in water and mix with 2.75 gm. of oxalic acid, 1.9840 

 gm. of malic acid, 2.2994 gm. of citric acid, 1.9396 gm. of tartaric 

 acid, and then dilute to 1 liter. For use, these two solutions are 

 mixed in equal parts; 25 gm. of air-dried soil, or 5 gm. of a fertilizer, 

 are shaken for half an hour in a half liter flask with 500 cc. of the 

 liquid. Phosphoric acid is determined in 200 cc. of the filtered 

 extract thus o))tained. 



Determination of cane sugar in condensed milk, L. Grunhut 

 and S. H. Ruber {Ztschr. Analyf. Chem., 39 {1900), No. 1, pp. 

 19-36). — The authors report a critical examination of the various 

 methods employed in the estimation of cane sugar in the presence of 

 milk sugar. In the analysis of condensed milk they consider inver- 

 sion by hydrochloric acid of the highest importance when methods of 

 reduction with Fehling solution, before and after inversion, are used. 

 If the quantity of cane sugar in a sample is to be drawn from the reduc- 

 ing power after inversion, the reduction before and after inversion 

 must be made undei- exactly the same conditions, as concentration of 

 solution and length of heating materialh^ influence the quantity of 

 cuprous oxid deposited. The gravimetric methods of Ost and Kjeldahl 

 are the oidy two known to the authors that fullill this condition, and 

 the Ost method has been proven both by Ost himself and by Schmoger 

 to be practically valueless for determining milk sugar, leaving only the 

 Kjeldahl method. 



G. Pjruhns has sliown that a considerable erroi- residts fi-oni a slight 

 decomposition of cane sugar by boiling 20 minutes with a very strong 



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