CHEMISTRY. 369 



No. 12, pp. 1633-1035).— In the metliod proposed 0.2 to 0.3 gm. of sub- 

 stance is placed in a tlask with 20 cc. of Avater (or in case of difiticnltly 

 sohible substances 20 cc. of alcohol), 10 cc. of a strong hydrochloric acid 

 sokition of tin chlorid containing- loO gni. of tin i)er liter, and 1.5 gm. 

 of tin dust. The mixture is heated over a snuill tianie until the tin is 

 dissolved and the solution is perfectly colorless. 



After cooling, 20 cc. of concentrated sulpliuric acid is carefully added. 

 If alcohol is used, this should be completely reduced before sulphuric 

 acid is added. 



The solution is digested until copious fumes of sulphuric acid ai)pear, 

 and after cooling the amid compounds are oxidized by the addition of 

 a little more than the calculated amount of potassium bichromate. In 

 the case of nitrates the use of bichromate is, of course, unnecessary. 



The remaining operations are carried out as usual. The results of 

 determinations of nitrogen in i)otassium nitrate and a number of nitro- 

 gen derivatives are reported, showing a close agreement with the cal- 

 culated percentages. 



Volumetric determination of nitric acid, D. Monnier and H. 

 AURIOL {Arch. tici. Phi/s. Xat. Gcmre, 31, p. 352; abs. in Bui. Soc. 

 Chim. Paris, 11-12 {1894), Ifo. 18 and 19, p. 988).~The apparatus 

 devised for the determination of free or combined nitric acid in water 

 is described. The method suggested is based on the reduction of 

 nitrates in an acid solution by nascent hydrogen evolved by sodium 

 amalgam. About half a liter of the water to be analyzed is evaporated, 

 and the amount of hydrogen evolved by a given weight of the amal- 

 gam as compared with the volume evolved by the same amount of 

 amalgam in pure water is measured. The difference is taken to cor- 

 respond to the hydrogen used in the reduction of the nitrates. 



The volumetric determination of virater-soluble phosphoric 

 acid in superphosphates by Kalmann and Meissels' method, C. 

 Glaser (Chem. Zt<j., is {ls9i), Xo. 80, pp. 1533, 1534). — Attention is 

 called to the fact that A. Eramerling^ proposed several years ago a 

 method based upon the same principle as that involved in the KaLmaun 

 and Meissels- method. A few possible sources of error are i^ointed 

 out and a substitute for Kalmann and Meissels' method is proposed, in 

 which the principal modifications, are the carrying out of both titra- 

 tions (with methyl orange and i^henolphthalein) in the same aliquot 

 part of the solution and the addition of an excess of perfectly neutral 

 calcium chlorid solution before the titr{i,tiou with phenolphthalein is 

 undertaken. 



In calculating the results each cubic centimeter of tenth-normal 

 soda solution used in the first titration is taken to correspond to 7.1 

 mg. of phosphoric acid, and in the second titration to 3.55 mg. of phos- 

 phoric acid. 



I'Laudw. Vers. Stat., 1886, p. 429. 

 2Cbem.Zt^-., X8 (1894), No, 54, Repert., p. 180. 



