| Hydrated Vanadium Tri-iodide, VI3.6H2O, is prepared by reducing, electrolytically, a solution of vanadium pentoxide, V2O5, in hydriodic acid, until the product becomes green; more hydriodic acid is then added and the whole allowed to stand over lime and concentrated sulphuric acid at 0° C. Small green needles separate, which have the same crystalline form as the hydrated trivalent halides of titanium, iron, and chromium. These crystals are extremely hygroscopic and deliquesce in air to a brown liquid which is extremely unstable. |
| No definite oxyiodides of vanadium are known, although several substances of varying composition have been obtained by the action of vanadium pentoxide on hydriodic acid. |