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XXXVI. On Indium. 

 By F. Reich and Th. Bjchter of Freiberg in Saxony*. 



ALTHOUGH our investigations concerning the properties of 

 this new element and its compounds may appear incom- 

 plete, owing to the extremely small quantities of this body which 

 we have hitherto been able to obtain, we think it advisable to 

 publish the facts we have already ascertained, as there is no im- 

 mediate prospect of our obtaining an abundant source of the 

 new metal. 



The position of the brighter blue line seen in the spectroscope is 

 found to be on division 98 of the scale, that of the weaker on 

 135, when the sodium line is on 38, and the blue strontium 8 

 on division 93. (If Na be placed on 50 and Sr $ on 104, the 

 In a will be seen on 110, and In/8 on 147 f.) We may here 

 remark that if a suitable indium-salt be brought into the flame 

 of aBunsen'slanip, the flame becomes tinged a bright violet; so 

 that the presence of indium can be ascertained without the aid 

 of the spectroscope. 



The fact of the reduction of the oxide with carbonate of soda 

 on charcoal before the blowpipe has been confirmed, The metal 

 forms a soft, ductile bead, which imparts streaks to paper on 

 rubbing, and possesses a colour lighter than that of lead, being 

 about the same as that of tin. The metallic bead dissolves in 

 hydrochloric acid with evolution of hydrogen ; and a platinum 

 wire moistened with the solution exhibits in the spectroscope 

 the blue line very strongly, although but for a few moments. 



If the metal be heated by itself before the blowpipe, an easily 

 fusible incrustation is obtained, which, when hot, possesses a 

 dark yellow, but when cool a light straw-colour. This incrus- 

 tation is volatilized with difficulty, and imparts the characteristic 

 tint to the flame. 



We have always obtained the ignited oxide of a yellowish 

 colour, it has, however, invariably contained a trace of ferric 

 oxide. 



The hydrated oxide, as precipitated by ammonia, is white and 

 gelatinous, adhering to the sides of the precipitating-glass. Tar- 



* Communicated by Professor Koscoe. 



t I have examined the spectrum of a small specimen of oxide of indium 

 kindly sent me by Professor Richter of Freiberg. For the purpose of ob- 

 taining a distinct spectrum, I place a small portion of the oxide on a pla- 

 tinum loop, moisten with hydrochloric acid, and observe the light emitted 

 by a weak induction spark in passing over the chloride. In this way both 

 the indium lines are distinctly seen ; whereas if the bead be placed in the 

 gas-flame only one line is seen, and that but faintly. When the sodium 

 line is on division 50 of the scale of my instrument, and Sr 8 on 100*5, I 

 find In« on 107*5, and In/3 on 1400.— H. E. K. 



