録音材料酸化金属の整法

For the preparations of ferric oxide and ferrousferric oxide as the primary materials for ferrite magnets and magnetic metal-oxide for tape recording, the fine sand-iron and the special spongy-iron produced at TORIGAMI BRANCH FACTORY and at the METALLUGICAL LABORATORY of HITACHI-INZOKU Co., YASUGl are used respectively. The distributions of the particle-sizes of sand-iron, the iron contents by each grade of their particle-sizes, the solubilities of sand-iron and spongy-iron in hydrochloric acid and sulphuric acid, and then the effects of temperature on them are fundamentally researched.