Mn nodule samples were decomposed with HCl and fumed with H2S04. SiO2 was estimated by the standard procedure of HF. The residue, after the removal of SiO2, was fused with pyrosulphate and the filtrate was added to the main solution. The solution was made to a definite volume-stock solution. Barium was estimated from the residue left after pyrosulphate fusion as chromate. Iron was estimated by the dichromate titration using diphenylamine sulphonate as indicator after passing the solution through the Ag-reductor. Mn was estimated by the bismuthate procedure. R2O3 was precipitated from the stock solution by hexamine. The precipitate was ignited and fused with Na2CO3 boiled in water and filtered and Al2O3 was estimated by the oxine procedure. From the filtrate, from R2O3 precipitation, Ca was precipitated as oxalate and estimated. TiO2 was estimated colorimetrically by H2O2 in presence of H3PO4. Soda and potash were estimated by AAS after decomposing the sample with HCl and H2SO4. Ni, Co and Cu were estimated by AAS, after decomposing with HCl and removing the silica by filtration. +H20 was estimated in a separate sample by the Penfield method and moisture (—H20) by heating at 110°C. For phosphorous, the sample was decomposed with HCl, baked to eliminate silica and filtered. R2O3 was precipitated, filtered and dissolved in HNO3. Phosphorous was precipitated by nitroammonium molybdate and estimated by the acidimetric titration.
