CHEMISTRY. 737 



liters of citric acid was used in each case. The repeated extractions gave results 

 agreeing quite closely with tliose furnished by the mineral acid extraction, but con- 

 siderably higher than those given by the Wagner method. 



On the determination of citric-acid soluble phosphoric acid, M. Passon 

 {Chein. Ztg., 21 {190S), No. 4, p. 33). — The author describes a slight modification of 

 the oxidation method of Passon and Mach." 



Transformation of pyrophosphoric acid into orthophosphoric acid, H. 

 Grian [Coinpt. Bend. Amd. Sri. Pnrl^, 135 {1902), No. 22, pp. <J61-9r,;i). 



On the determination of calcium in the form of oxalate, V. Paguiref [ZJiur. 

 RKs.-i. Fl:. Khim. Oh.-<Iicl(., .J.^ (190..'), No. ;?, pp. 195-199; ahti. in Bid. Soc Chim. Paris, 

 3. tii'i:, 30 {1903), Nu. 1, p. 95). — In order to obtain a precipitate wliich will not run 

 through the filter the author adds to a neutral solution of calcium salt in the cold an 

 excess of oxalic acid, stirring the solution at the same time; then ammonia, drop by 

 drop, until a slightly alkaline reaction is obtained. The solution is heated and stirred 

 continuously to drive off the excess of ammonia. The precipitate thus obtained is of 

 the same composition as that obtained by the ordinary method, but is more com- 

 pact, settles completely in less than 4 hours, and does not pass through the filter. 



A rapid gravimetric method of estimating lime, F. B. Guthrie and C. R. 

 Baker (Ayr. (la:. Neir South W(tles, 13 (1902), No. 12, pp. 1215, 1216).— hime is pre- 

 cipitated as oxalate and reduced to oxid by ignition in a platinum crucible with 

 ammonium nitrate. The crucible is placed in a slanting position and partly covered 

 with the lid. Heat (from a Bunsen burner) is applied to the lid until danger of 

 spurting is passed, when the crucible is heated directly for about 5 minutes. 



On the determination of free lime in Thomas slag-, M. Bischoff {Chern. Ztg., 

 27 {1903), No. 4, P- 33). — Comparati ve tests of Scheibler's sugar-solution method and 

 extraction with water are reported. The first gave much higher results than the 

 second, tut it was found that on boiling the sugar-solution extract a precipitate of 

 calcium carbonate was obtained, showing that the sugar-solution extracts carbonate 

 as well as free lime. For this reason the extraction with water is considered the 

 more reliable method. 



Lime determinations by means of Passon's apparatus, M. Passon {Deut. 

 Laiidw. Fre.%^e, 30 (1903), No. 4, pp. 26, 27).— It is stated that the determinations by 

 means of the apparatus are too high when large amounts of sand, clay, etc., are 

 present. A table of corrections to be used is given. 



Passon's lime test, T. Pfeiffer {Deut. Landw. Presse, 30 {1903), No. 6, p. 44)- — 

 Reports results of tests which indicate the unreliability <W the method, even with 

 corrections applied as suggested by the author. (See above. ) 



On the determination of perchlorates, M. Honig {CJiein. Ztg., 27 {1903), No. 4, 

 2>p. 32,33). — The author fuses the salt containing perchlorate with iron filings in 

 a nickel crucible. This reduces the perchlorate to chlorid, which is determined 

 gravimetrically. 



A titration method of determining hardness of water by means of aqueous 

 soap solutions, A. Gawalowski (/fce/u'. Anubjt. Chern., 41 {1902), No. 13, pp. 748-752, 

 figs. 2). — Water solutions (1 cc. corresponding to 0.0012 gm. CaO) of neutral sodium 

 oleate or of commercial soap made of soda and cocoanut oil are recommended. The 

 method of titration is practically the same as that usually employed, except that 

 green glass flasks marked at 25, 50, 75, and 100 cc, for use with waters of different 

 degrees of hardness, are employed, and a small amount of carmine tinctiire is added 

 to assist in defining moie clearly the point of saturation. 



A volumetric method for the determination of tannin and the analysis of 

 tanning materials and extracts, A. Thompson {Compt. Rend. Acad. Sci. Paris, 

 135 {1902), No. 17, pp. 689-691). 



ffZtschr. Angew. Cham., 1896, p. 129 



