Abstract: A drill shoe adapted to fit onto a drill pipe of external diameter d.sub.e and internal diameter d.sub.i comprises an externally stepped cutting surface comprising a plurality of steps, the diameters of the steps increasing as they progress away from the tip of the shoe. The maximum external diameter D.sub.e of the shoe is greater than the external diameter d.sub.e of the drill pipe. The shoe also comprises an internal, substantially cylindrical, inner surface of diameter D.sub.i, D.sub.i being less than the internal diameter d.sub.i of the drill pipe.The shoe is suitable for use in a vibratory drill string for obtaining cores from unconsolidated geological formations, such as soil, sand and gravel or similar materials.

Abstract: A method of inhibiting corrosion of a metal surface comprises applying to the metal surface an organic solvent in which is dissolved a phosphate monoester of a hydroxyalkyl acrylate or a hydroxyalkyl alkylacrylate which phosphate monoester has the general formula; ##STR1## where R.sub.1 is hydrogen, a methyl group or an ethyl group R.sub.2 is an alkyl group having from 2 to 10 carbon atoms andn is a positive integer from 1 to 20The solution may also contain a diester of a hydroxyalkyl acrylate, a diester of a hydroxyalkyl alkylacrylate, hydroxyalkyl acrylate or hydroxyalkyl alkylacrylate.The method may also improve the adhesive strength of a subsequently applied protective coating e.g. paint.