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).
Molybdenum monoxide, MoO.n(H 2 O), is a black powder obtained when the dichloride is boiled with concentrated potash solution.
If a suspension of lead dichloride in hydrochloric acid be treated with chlorine gas, a solution of lead tetrachloride is obtained; by adding ammonium chloride ammonium plumbichloride, (NH 4) 2 PbC1 6, is precipitated, which on treatment with strong sulphuric acid yields lead tetrachloride, PbC1 4, as a translucent, yellow, highly refractive liquid.
The dichloride is an amorphous, readily fusible, almost black solid.
The tetrachloride is a white crystalline solid which is formed by the action of chlorine on the dichloride or by sulphur chloride on the element.
It is remarkable that the position of the halogen in the molecule has no effect on the heat of formation; for example, chlorpropylene and allylchloride, and also ethylene dichloride and ethylidene dichloride, have equal heats of formation.
Molybdenum dichloride (MoC1 2) 3 or Cl 4 Mo 3 C1 2 (chlormolybdenum chloride), is prepared (together with some tetrachloride) by heating the trichloride in a stream of carbon dioxide (C. W.