The atomic weight of indium has been determined by C. Winkler and by R.
Sodium gives an intense and persistent yellow flame; lithium gives a carmine coloration, and may be identified in the presence of sodium by viewing through a cobalt glass or indigo prism; from potassium it may be distinguished by its redder colour; barium gives a yellowishgreen flame, which appears bluish-green when viewed through green glass; strontium gives a crimson flame which appears purple or rose when viewed through blue glass; calcium gives an orange-red colour which appears finch-green through green glass; indium gives a characteristic bluish-violet flame; copper gives an intense emerald-green coloration.
The precipitated indium hydroxide is converted into a basic sulphite by boiling with excess of sodium bisulphite, and then into the normal sulphite by dissolving in hot sulphurous acid.
The elements gallium and indium were discovered in blende.
To take an example: 38 parts of indium combine with 35.4 parts of chlorine; hence, if the formula of the chloride be InCI, InC1 2 or InC1 3, indium has the atomic weights 38, 76 or 114.
Three chlorides of indium are known: the trichloride, InC13j a deliquescent salt, formed by heating a mixture of the oxide and carbon in a current of chlorine; the dichloride, InCl2, obtained by heating the metal in hydrochloric acid gas; and the monochloride, InCl, which is prepared by distilling the vapour of the dichloride over metallic indium.
We must refer to Kayser and Runge's Handbuch for further details, as well as for information on other spectra such as those of silver, thallium, indium and manganese, in which series lines have been found.
The specific heat of indium is o 057; and the atomic heats corresponding to the atomic weights 38, 76 and 114 are 3.2, 4.3, 6.5.
An indium ammonium alum, In2(S04)3 (NH4)2S04.24H20 is known.
The hydroxide, In(OH) 3j is prepared, as a gelatinous precipitate, by adding ammonia to any soluble indium salt.