(a) Laboratory size, hammer type, with H.P. heavy duty motor (single phase) 220 volts, 50C/S A.C. consisting of four steel hammers fixed to a disc of 3" in dia 1" thick through which passes a shaft being revolved at 3000 R.P.M. The hammers are enclosed in a C.I. drum, the sides and upper surface of which are roughened. The inner surface is undulating. The lower part of drum is made of chrome plated brass and is detachable so that , SS sieves of different mesh size (a set of three sieves of coarse, medium and fine(Supplied with the instrument) can be easily placed. Hopper is made of die casted aluminium , Built on angle iron frame of size 24"x14"x20" high.