11.By technique checking every operations of recovery circuit,calculating the classification of spitzkasten and cyclone,thickening efficiency,assaying the ash of every operations.
12.Bilateral oal thickenings of the surface ectoderm, called nasal placodes, then deelop on each side of the inferior part of the frontonasal prominence.
13.The composition. properties, reaction activity, capacity of frothing and defrothing of phosphate rock and the preparation, thickening and clarification of wet phosphoric acid are stutiied.