3 Published Papers

Abstract

(I) The System Ferrous Oxide-Phosphoric Acid-Water and some of its Oxidation Products. The existence of the monohydrogen ferrous phosphate Fe(HPO₄),H20 (or 2FeO, P₂O₅, 3H ₂O) has "been confirmed. This com-pound was described by Debray but subsequently Erlenmeyer cast doubt on Debray's results. The compound has been obtained in two forms, viz. "amorphous" and crystalline, the latter showing a decidedly lower solubility. In addition a dihydrate Fe(HPO₄), 2H₂O (or 2FeO, P₂O₅, 5H₂O) has been shown to exist. The dihydrogen phosphate Fe(H₂PO₄) ₂, 2H₂O (or FeO, P₂O₅, 4H₂O) described by Erlenmeyer has been confirmed. It is thought that the ferrous phosphates are not complex.

By the oxidatiod of phase mixtures poor in acid a red-brown ferric phosphate betaFe ₂O₃, P₂O₅, 4H₂O is deposited, which is only stable when ferrous iron is present in the liquid phase (at 70°). By completing the oxidation the substance changes both in crystalline form and colour (to pink) to a solid having the same empirical composition. It is thought2that the latter is a complex ferri-phosphate, whilst the former is a true ferric phosphate.

(II) An Aeparatus for the Viscosimetric Determination of Transition Points. By means of an apparatus combining the functions of a viscometer and a stirrer the transition points Na₂SO₄, 10 ↔ OH₂O, NiSO₄, 7 ↔ 6H₂O, and Na₂HPO₄, 12 ↔ 7H₂O have been determined.

(III) The System Ferric Oxide-Arsenic Acid-Water at Low Concentrations of Arsenic Acid. The following solid phases have been found to exist between 2·6 and 23·13% of As₂O₅ in the liquid phase at 25°: Fe₂O₃, As₂O ₅, xH₂O (where x is probably near 6); Fe ₂O₃, 2As₂O₅, 8H₂O. The latter compound has not been described before as far as is known. Its existence provides evidence that the ferric arsenates, like the phosphates, are complex. No basic salts were obtained. The system was characterised by an extreme sluggishness in approaching equilibrium.