Production of gamma ferric oxide

Claim 1

A PROCESS FOR THE PRODUCTION OF SUBSTANTIALLY PURE GAMMA FERRIC OXIDE IN THE FORM OF A FINELYDIVIDED POWDER CONSISTING OF CRYSTALLINE PARTICLES OF SUBSTANTIALLY UNIFORM SIZE AND DIAMETER LESS THAN ONE MICRON, WHICH COMPRISES THE STEPS OF HEATING A FINELY-DIVIDED COMPOUND CONSISTING OF CRYSTALLINE PARTICLES OF SUBSTANTIALLY UNIFORM SIZE AND OF DIAMETER LESS THAN ONE MICRON, WHICH COMPOUND IS A MEMBER OF THE GROUP CONSISTING OF IRON OXALATE AND IRON FORMATE, AT A TEMPERATURE BELOW 600* C. IN AN ATMOSPHERE WHICH IS SUBSTANTIALLY NON-REACTIVE WITH FERROSOFERRIC OXIDE AT TEMPERATURES BELOW 600* C., SAID HEATING BEING CONTINUED UNTIL THE SAID COMPOUND IS SUBSTANTIALLY COMPLETELY CONVERTED TO FERROSOFERRIC OXIDE, COOLING TO ABOUT ROOM TEMPERATURE THE FERROSOFERRIC OXIDE THUS FORMED, THOROUGHLY DAMPING THE COOLED FERROSOFERRIC OXIDE THROUGHOUT ITS MASS WITH WATER, DRYING THE DAMPED FERROSOFERRIC OXIDE IN AIR AT A TEMPERATURE BETWEEN 100* C. AND 200* C. TO CONVERT THE FERROSOFERRIC OXIDE TO SUBSTANTIALLY PURE GAMMA FERRIC OXIDE, CRUSHING THE DRIED PRODUCT, AND RECOVERING THE GAMMA FERRIC OXIDE.