860 EXPERIMENT STATION RECORD. 



cLlorid is collected and weighed. The actual and the theoretical 

 auiounts of silver chlorid agree very closely. 



For the determination of the perchlorate in saltpeter about 10 gm. is 

 used. If a chlorate is to be analyzed, ib is treated in the same way 

 except that it is put in a smaller tube to avoid premature contact with 

 the acid.— J. t. Anderson, 



Recognition of perchlorate in saltpeter, Erck {CItem. Ztg.^ 2i 

 (1S97), jN"". 1, p. 10). — Dissolve 100 gm. of saltpeter in 80 cc. of water, 

 add 7 cc, of nitric acid (sp. gr. 1.4), warm, and then add 8 cc. of alco- 

 hol (OL'C' Tr.) and boil about 5 minutes. This treatment drives off all 

 the chlorin which may be i)resent in the form of chlorid and chlorate, 

 and testing with silver nitrate shows no reaction. Saturate with 

 sodium carbonate, wash the contents into a platinum dish, evaporate 

 to dryness and ignite. Take up the residue with warm water and test 

 for chlorin with silver nitrate. The presence of chlorin indicates that 

 the perchlorate existed in the saltpeter under examination. — J. t. 



ANDERSON. 



The mechanical analysis of basic phosphatic slags, H. W. 

 Wiley {Jour. Amer. Chem. Soc, 19 {1S97), No. 1, pp. l!)-22, pis. 3).— 

 The action of a solution of ammonium citrate on basic phosphatic slag 

 is different with different samples. Some samples are found to contain 

 larger proportions of particles of siliceous slags, iron, and steel than 

 others. This makes a mechanical analysis desirable as a preliminary 

 to the determination of the available phosphoric acid. The author 

 describes a tentative method for the mechanical analysis of phosphatic 

 slags, by which the coarser portions are separated by means of sieves 

 of bolting cloth and the finer portions by subsidence in alcohol. It 

 was found that the finest portions contained the highest percentages 

 of both total and available phosphoric acid. The range for total j^hos 

 phoric acid was from 13,91 per cent to 18,21 per cent and for availalde 

 phosphoric acid from 0.21 per cent to 14,01 per cent. — F. w. morse. 



Critical studies of the volumetric analysis of the caustic alka- 

 lies and alkaline carbonates and the use of phenolphthalein and 

 methyl orange as indicators, F. W. Ki ster {Zt.schr. anor(/an. Chem., 

 13 {1896), No. 2-3, pp. 127-150). — An exhaustive investigation of the 

 various volumetric methods for analyzing mixtures of caustic alkalies 

 and alkaline carbonates and the behavior of methyl orange and phe- 

 nolphthalein under such conditions. 



C. Winkler's method is shown to be the only correct process for 

 accurately determining the amount of alkaline hydroxid present in a 

 mixture containing carbonate. The total alkali can be accurately esti- 

 mated by titration with methyl orange as the indicator. 



The color of methyl orange is strongly affected by carbon dioxid. It 

 is therefore necessary in titrating solutions of alkali which contain 

 carbonates to always stop at a certain normal tint, which is defined by 

 comparison with an equally concentrated water solution of the color 

 saturated with carbonic acid. 



