The mineral compositions of the clays from a red earth and a black cotton soil from Hyderabad, Deccan State, India, occurring in close proximity in the field are determined. Both soils are derived from the same or from very similar parent rocks, a coarsely crystalline granite or gneiss.For both soils there is practically no variation in the mineralogical composition of the clay throughout the profile, but for any given clay there is some variation with grain size. The main contrast between the two is that the red clay contains predominantly kaolinite or halloysite, whereas the black clay contains mainly beidellite, a member of the montmorillonite group. The topography appears to be the principal factor associated with this difference in minerals, and the processes of weathering believed to have produced the contrasted clays are discussed with reference to experiments on the leaching of felspar in the laboratory and on hydrothermal synthesis.

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Eleven laboratories evaluated the double extraction procedure for the determination of bacitracin methylene disalicylate in swine and poultry feeds at 22, 44, and 88 g/2000 lb. Bacitracin activity was determined on each of 2 days using blind duplicates in a random order. All collaborators submitted their data for statistical evaluation. No significant difference was found between the assay results and the label claim at 22,44, and 88 g/2000 lb for swine and poultry feed. For both feed types, reported ranges at 95% confidence limit for 22,44, and 88 g/2000 lb were 17-30 g/2000 lb, 29-61 g/2000 lb, and 64-112 g/2000 lb, respectively. The microbiological plate assay procedure for determination of BMD in complete feed was adopted first action by AOAC INTERNATIONAL.