204 EXPERTMENT STATION RECORD. 



lein as indicator, (> cc. of iiotitralizod forniaidoliyde soliilion arc added, and the 

 soliitiou is titi'ated with tenth-normal sodium hydroxid solution." 



A bacteriolog'ical method for determining' available organic nitrog'en, 

 J. :\r. McCandless and F. C. Atkinson (Amcr. Fert., 3Ji (1011), No. 7, pp. 11, 18; 

 Jour. Indus, and Enf/in. Clicm., 3 (1911), No. 3, pp. 171/, 175). — The author de- 

 scribes a method similar to that proiwsed by Lipman (E. S. R., 28, p. 302), in 

 which aqueous extracts of cottonseed meal and other organic nitrogenous fer- 

 tilizers were shaken up with soil and incubated for 210 hours at from 38° to 

 40° C, and the rate of ammonia formation under these conditions determined. 



Separation of calcium from magnesium, E. Murma*nn (Ztschr. Analyt. 

 CJirm., 1,0 (1010), No. 11, pp. 688-608; ahs. in Ztschr. Angew. Chem., 23 (1010), 

 No. 1,7, p. 22.29). — According to the author an absolute separation of calcium 

 from magnesium is possible only when enough sulphuric acid is present with DO 

 per cent alcohol to combine with or fix the calcium. 



For conducting the separation the author adds a sufficient amount of titrated 

 sulphuric acid to the solution of the chlorids and nitrates of calcium and mag- 

 nesium to fix all the calcium, and after evaporating off the sulphuric acid aims 

 to leave very little of the magnesium present as a sulphate. The residue is 

 treated with 90 per cent alcohol, and the residual calcium sulphate filtered off, 

 washed with the same strength alcohol, and treated in both an alkaline and 

 acid solution to separate it from the magnesium which came down in the origi- 

 nal precipitation as sulphate. 



Precipitation of magnesium as ammonium magnesium arsenate, E. Raffa 

 (Go^. Chim. Ital., 39 (1909), I, No. 2, pp. 15 ',-162; ahs. in Chem^ Abs., 5 (1911), 

 No. 5, p. 844)- — As the solubility of ammonium magnesium arsenate is about 

 0.037 part per 100 parts of water at 20° C, and 0.00303 to 0.00280 part per 100 

 in a mixture used for w^ashing the precipitate and consisting of 1 part 10 per cent 

 ammonia (NH3) and 2 parts of water, the author proposes the use of the same 

 procedure as described in previous work (E. S. R., 20, p. 1006). The precipitate 

 is somewhat more soluble than the phosphate. 



Titrametric determination of combined sulphuric acid by the barium 

 chromate method, H. Roemer (Ztscli/)\ Analyt. Chem., 1,9 (1910), No. 8, pp. 

 1,90-1,92) .—TlhG method is a modification of the Holliger method (E. S. R., 23, 

 p. 214) and is as follows: 



To the salt, which is dissolved in hot water containing some hydrochloric 

 acid, add the requisite amount of one-balf-normal barium chlorid solution, boil, 

 titrate with an equivalent amount of standard solution of potassium bichromate 

 (36.9 gm. per liter), add ammonium hydrate until the barium chromate i5epa- 

 rates, boil again, and filter off the barium sulphate and barium chromate. As 

 the filtrate now contains an amount of chromate equivalent to the amount of 

 sulphate originally present, it is titrated after acidifying with a few drops of 

 sulphuric acid with ferrous ammonium sulphate, using potassium ferricyanid 

 as an indicator. This method is good where amounts as low as 0.1 per cent of 

 sulphuric acid (SO3) are present. 



In regard to the chemical analysis of moor soils and its value for 

 cultural purposes, H. von Feilitzen (Vcrhandl. Internat. Ag'rogeol. Konf. 

 [8tockJiolm], 2 (1010). pp. 160-167).— Attev reviewing the existing work on this 

 subject, the author points out the advantage of utilizing for moor soils the 

 extraction method which employs first a 4 per cent and then a 2 per cent hydro- 

 chloric acid solution for the purpose. A description of the method as used at 

 the station of the Swedish Moor Culture Society is given, with a description 

 of the method for interpreting the analytical results. For ordinary purposes 

 quantitative analyses are made of the organic matter, the residue after calci- 

 nation, and the calcium and nitrogen content, together with qualitative tests 



