Chemical Notices : — M. Bottger 6*??, Indium. 881 



the ^-dimensional space. And this curve must be such that to 

 given values of (x, y) there shall correspond n points on the 

 curve ; that is, treating (x, y) as constants, the surface or one- 

 fold locus yjr(x, y, c { , c 2 .. . c k )=0, and the curve or (k— l)-fold 

 locus C, shall meet in n points. The conclusion stated in the 

 foregoing quasi-geometrical form is, that the solution of the differ- 

 ential equation may be exhibited in the form ty(x,y, c 1} c 2 . . .c k ) = 0; 

 viz. i|r is a rational and integral function of (x, y, c v c 2 . . . c k ), 

 where (c v c 2 . . . c k ) are the coordinates of an arbitrary or variable 

 point on a curve or (k — l)-fold locus C in a k- dimensional space, 

 which curve meets the surface or one-fold locus ^r{x, y, c v c 2 . . . c k ) 

 in n points, and where yjr regarded as a function of (x } y) is not 

 rationally decomposable into factors. 

 Cambridge, October 13, 1866. 



LII. Chemical Notices from Foreign Journals. 

 By E. Atkinson, Ph.D., F.C.S. 



[Continued from vol. xxxi. p. 459.] 



BOTTGER* describes the following method of separating in- 

 dium from the incrustation obtained from furnaces for roast- 

 ing zinc. About 2 cwt. of incrustation was obtained from the 

 chimney of the furnaces at the Juliushutte at Goslar. This depo- 

 sit, in quantities of 6 to 8 pounds, was treated in spacious porcelain 

 dishes with crude hydrochloric acid and boiled for half an hour. 

 The liquid was then twice filtered through linen, and allowed to 

 stand for six hours at the ordinary temperature in contact with 

 thick sheets of zinc. The black velvety metallic powder which 

 deposited was collected on a double filter, and washed with boil- 

 ing water until the filtrate gave no longer any reaction for iron. 

 The residue, consisting of copper, arsenic, cadmium, thallium, 

 and indium, was boiled with hot concentrated solution of oxalic 

 acid, the liquor diluted with much water, and filtered. The fil- 

 trate, which consisted of oxalate of indium containing cad- 

 mium and thallium, was precipitated with an excess of ammonia. 

 The mucilaginous precipitate, resembling hydrate of alumina, still 

 contained cadmium and thallium : it was boiled out a few times 

 with ammonia, and then washed out with hot water until no more 

 thallium could be detected by means of the spectroscope. If this 

 hydrated oxide of indium still contained traces of iron, the latter 

 metal was best separated by Winkler's method f. The oxide of 

 indium was dissolved in hydrochloric acid, the iron reduced with 

 sulphite of soda, and the cooled solution agitated for a few mi- 

 nutes with freshly precipitated carbonate of baryta, while car- 



* Pol. Notizen, vol. xxi. p. 177. 

 t Phil. Mag. S. 4. vol. xxx. p. 443. 



