Thallium dichloride, TlCl₂

Thallium dichloride, TlCl₂ or TlCl.TlCl₃, is the final product of the action of dry chlorine on dry thallous chloride at the ordinary temperature. The absorption of chlorine is at first rapid, but is subsequently very slow. Thallium dichloride is a pale yellow, hygroscopic solid which may be kept indefinitely in an atmosphere of dry chlorine at the ordinary temperature without any further absorption of the gas occurring. It is decomposed by water into thallic chloride and thallium sesquichloride.