222 EXPERIMENT STATION RECORD. 



On a serious error in the method of Kubel-Tiemann for the determina- 

 tion of organic matter in drinking- ■waters, Duyk {A)in. Cliim. Analyt., 6 {1901), 

 PI). 121-124; (lbs. in Chem. CentU., 1901, I, No. 20, i^. 1113).— The author finds that 

 sodium chlorid in acid solutions interferes to a marked extent with the oxidation of 

 organic substances dissolved in water. It is therefore necessary before applying 

 such methods to remove the chlorin. For this purpose the author uses silver oxid 

 (Ag,0). 



Determination of nitric nitrogen in water by means of stannous chlorid, 

 11. Henriet {Coinpt. Bend. Acad. Sci. Paris, 182 {1001), No. 16, pp. 966-968) .—Xi the 

 boiling temperature stannous chlorid in presence of hydrochloric acid converts nitric 

 nitrogen into hydroxylamine hydrochlorid as follows: 3 SnOla+KNOg+S HC1= 

 3 SnCl^+NHa OH HCl-{-KCl+2 HjO. This reaction may be used in determining 

 nitrates by adding an excess of stannous chlorid of known strength and titrating the 

 excess with iodin. The stannous chlorid used is prepared by dissolving 14 gm. pure 

 tin in 1 liter of pure hydrochloric acid. The solution is kept in a flask from which 

 air is excluded. The iodin solution is prepared by dissolving 8 or 9 gm. of iodin and 

 20 gm. of potassium iodid in 1 liter of distilled water. Its strengtli is determined by 

 titration with sodium hyposulphite, or with a solution of potassium nitrate of known 

 strength. 



Apparatus for the determination of nitrogen in nitrates by the Schulze- 

 Tiemann method {Bohm. Ztschr. Zuckerind., 25 {1900), pp. 356-358; abs. in Chem. 

 Centbl, 1901, I, No. 22, p. 1216, fig. 1) . 



On the determination of chlorin in natural waters, its accuracy and sig- 

 nificance, E. G. Smith {Trans. Wisconsin Acad. Sci., Arts, and Letters, 13 {1901), 

 pt. 1, 2>p- 359-365). — This is a brief discussion based upon the author's experience in 

 examination of waters of the accuracy of three methods commonly used for deter- 

 mining chlorin, namely, the gravimetric method, and the volumetric methods of 

 Mohrs and Volhard. Of these the author has found Mohrs' method most reliable, 

 and the modifications of it which he has found necessary for the greatest accuracy 

 are given in detail. 



Detection of bicarbonates in waters, E. Pozzi-Escot {Ann. Chim. Analyt., 6 

 {1901), pp. 135, 136; abs. in Chem. Centbl., 1.901, I, No. 20, p. 1113). — For this pur- 

 pose the author adds to 250 cc. of the water a few drops of a solution of 0.5 gm. of 

 pyrogallol in 5 to 6 cc. of water, to which 2 drops of officinal iron chlorid solution has 

 been added. If carbonates or bicarbonates are present a violet or amethyst color 

 appears. Ammonia interferes with the reaction. 



Determination of sulphids, hydrosulphids, and thiosulphates coexisting 

 in solution especially in sulphurous mineral waters, A. Gautier ( Co)npt. Bend. 

 Acad. Sci. Paris, 132 {1901), No. 9, pp. 518-523). 



Notes on recent work of the German Sugar Commission appointed for fix- 

 ing normal standards, A. Herzfeld {Ztsclir. Yer. Pent. Zuckerind., 1900, pp. 1126- 

 1128; abs. in Jour. Soc. Chem. Ind., 20 {1901), No. 3, p. 268).— The Brix tables in 

 use at present are based on determinations made by Balling in 1839. The new 

 tables, worked out by the German Sugar Commission, are somewhat higher than 

 the old tables. 



Volumetric estimation of invert sugar, F. Stolle {Ztschr. Ver. Dent. Zucker- 

 ind., 1901, No. 541, II, pp. 111-117; abs. in Jour. Chem. Soc. ILondon], 80 {1901), 

 No. 462, II, pp. 286, 287). — By the proposed method a portion of the solution of the 

 invert sugar is added to a known volume of Fehling's solution, the excess of the 

 latter being estimated by titrating with an ammoniacal solution of potassium cyanid. 

 In titrating the color is destroyed by the formation of potassium cuprous cyanid. 



The determination of mannose in sugar-cane products, H. Pellet {Bid. 

 Assoc. Chim. Sucr. et Distill., 18 {1901), No. 10, pp. 755-76^9).— Methods of analysis. 



