CHEMISTRY. 663 



Determinations of alumina and oxid of iron in mineral phos- 

 phates, manures, sulphate of alumina, alum, etc., 11. T. Thomp 



So.N [Jniir. iSoc. ('Item. IiuL, ir, [is'ju)^ Xo. 1l\ p. so8,8(il>). — The unsat- 

 isfaetoiy character of the methods in use for the precipitation of iron 

 aud alumina as phosphates is due to the fact that all the conditions 

 which tend to cause inaccuracy are not taken into account. It is 

 necessary to consider \\o\\ to obtain the i^recipitate free from calcium 

 phosphate as well as to obtain and keep it in the perfectly normal con- 

 dition. The presence of anunonium acetate favors the precipitation of 

 calcium pliosphate, even in tlie cold. The neutralization process for- 

 merly proposed by the author ' avoids this difiticulty. To the cold solu- 

 tion of the phosphate ammonia is added until it is neutral or only 

 faintly acid to laciuoid paper, when the whole of the aluminum aud 

 iron phos[)hates will be precipitated and the calciuui phosphate will 

 remain in solution. In order that the phosphates of iron aud alumina 

 be normal, at least 1.^ times the amount of phosphoric acid theoretic- 

 ally required nuist be i)reseut, otherwise the phosphates will be basic 

 aud of uncertain composition. To preserve the normal composition of 

 the x^'ecipitate, it is washed with a 1 per cent solution of ammonium 

 nitrate containing- 0.3 gm. of diphosphate of ammonium (XII4HPO4J 

 per liter. The ammonium phosi)hate must be exactly neutral to 

 methyl orange. If tluorids are present, the solution of the phosjihate 

 is to be previously evaporated with nitric acid. The process serves 

 also for the separation of alumina and oxid of iron from cobalt, nickel, 

 zinc, and manganese, as well as from calcium and magnesium. — A. m. 



PETER. 



A modification of the Grunning method for nitrates, J. Fields 



[Jony. Aiitcr. ('hem. iSoc, IS (i^.'^Oj, Xo. i'^,pp. Il0:2-ll()i). — The modi- 

 fication consists in substituting* for the 5 gm. of sodium thiosulphate 

 and 10 gin. of potassium sul[)hate of the official method G to 7 gm. of 

 potassium sulphid, which is added in small i)ortions, the tiask being 

 thoroughly shaken after each addition. It is claimed that with this 

 reagent frothing is avoided and the time of digestion shortened. — f. w. 



MOUSE. 



The determination of sulphuric acid or of barium, J. Edmunds 



[Cliein. Xews, 71 {1^90), Xo. 1!J;J5, p. J 87). — The method is intended 

 especially for determining sulphuric acid in water. Seventy centi- 

 meters of the water is first titrated with an excess of deci-normal 

 barium nitrate, the excess of barium i)recipitated with an excess of 

 deci-normal potassium chromate, and the excess of potassium chrom ate 

 precipitated with an excess of deci-normal silver nitrate. The excess 

 of silver nitrate is deteruiined in the usual way in a portion of the 

 filtrate, and from this data the sul])huric acid is calculated. — b. w. 



KILGOEE. 



Jour. S(><'. Cliein. lud., 5 (1886), p. 152. 



