536 EXPERIMENT STATION RECORD. 



becomes colorless, or in the case of quickly decolorized samples, for at least 1 hour 

 from the time the potassium sulphate is added. 



" (7) The Dyer modification appears to combine the advantages of the other meth- 

 ods ( Kjeldahl-Wilfarth, Gunning, and Arnold- Wedemeyer) now recommended by the 

 Association of Official Agricultural Chemists for the determination of nitrogen in 

 organic compounds." 



The quantitative determination of phosphoric acid and nitrogen in organic 

 substances by means of sodium peroxid, F. von Konek (Ztschr. Angew. Chem., 

 17 {1904), No. 26, pp. 886-888; al>x. in Chem. Centbl., 1904, II, No. 5, p. 472).— In a 

 previous article the author showed how the phosphorus of organic matter could be 

 quantitatively converted into phosphoric acid by ignition with sodium peroxid. 

 In this article lie points out how the nitrogen may also he quantitatively converted 

 into nitric acid by the same process, namely, by ignition in a nickel-lined cylinder 

 with close-fitting cap, the nitric acid in the resulting product being determined by 

 the Devarda method. 



The quantitative determination of organic nitrogen by means of sodium 

 peroxid, F. von Konek and A. Zohls (Ztschr. Angew. Chem., 17 (1904), No. 81, pp. 

 1098-1095; nl*. in chem. Centbl., 1904, II, No. 11. />. 845). — The authors report further 

 studies of Konek's method, noted above, in which it was found that sodium peroxid 

 does not completely convert the nitrogen of pyridin, chinolin, and similar com- 

 pounds, or of aromatic nitrogen compounds, into nitric acid. 



On the other hand, it proved reliable and efficient in case of aliphatic compounds, 

 and was successfully employed on various kinds of meals as follows: Dry 0.5 gm. of 

 the meal at UK) to 102° C, transfer to a nickeled steel cylinder, and mix first with 

 12 gm. of sodium peroxid and later stir in 5 to 6 gm. of the same substance and 1 gm. 

 of persulphate-tartaric acid mixture (2 parts of KS0 4 and 1 part of tartaric acid ). 

 Screw down the cover so that it is water-tight and tire the mixture with a glowing 

 iron wire. Determine the nitric acid in the resulting product by the I >evarda method. 



The use of sodium peroxid in analysis, H. H. Pringsheim (Ztschi\ Angew. 

 Chem., 17 (1904), No. 38, pp. 1454, 1455). — The author states that by using a smaller 

 amount of sodium peroxid (3 to 5 gin.) than that recommended by Konek violent 

 explosion is avoided when the mixture is fired and the necessity for the use of a close- 

 fitting cover to the cylinder is obviated. A method of this kind has been sucessfully 

 used by the author in the determination of the halogens, phosphorus, and arsenic. " 



The determination of nitrogen, PI Jalowetz ( Allg. Ztschr. Bierbrau. n. Malz- 

 fabrik., 1904, May; abs. in Chem. Centbl, 1904, II, No. 1.5, p. 1068).— The author calls 

 attention to the error which may be introduced by alkali dissolved from the glass 

 flasks and tubes used in the distillation apparatus in the Kjeldahl method. He reports 

 determinations of nitrogen in barley in which this error corresponded to 0.4 to 1.2 per 

 cent of protein. 



To what extent does the alkalinity of the glass apparatus affect the accu- 

 racy of the Kjeldahl determination of nitrogen? K. Barelt and H. Schone- 

 wald ( Wchnschr. Bran., 21 (1904), )>■ 523; abs. in Chem. Centbl, 1904, II, No. 15, p. 

 1068) . — The errors due to solution of alkali from the glass were somewhat smaller than 

 those found by Jalowetz (noted above), but increased with the increase of the period 

 of distillation and were greater with new apparatus than with old. 



An apparatus for the determination of nitrogen, Nicolas and Delaud (Bui 

 Soc. ('him. Paris, 3. ser.,31 (1904), No. 20-21, pp. 1193, 1194).— The apparatus described 

 is a modification of that of Porcher and Brisac (E. S. R., 14, p. 631) designed for the 

 determination of nitrogen by the decomposition of ammonium salts under the action 

 of sodium hypobromite. 



«Ber. Deut. Chem. Gesell., 36 (1903), p. 4244. 



