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.
The pure metal may be obtained by reducing vanadium dichloride in hydrogen, the operation being exceedingly difficult (for details, see Roscoe's original papers).
Vanadium dichloride, VC12, is a green crystalline solid obtained when the tetrachloride is reduced with hydrogen at a dull red heat.
Fournier (Comptes rendus, 1901, 150, p. 102) obtained phosphorus dichloride, P2C14, as a colourless, oily, strongly fuming liquid, freezing at -28° and boiling at 180° with decomposition.
Selenium dichloride, Se 2 C1 21 is obtained by the action of chlorine on selenium; by the action of phosphorus pentachloride on selenium or the dioxide; by the action of hydrochloric acid on seleno-sulphur trioxide (E.