For unattended grinding of materials, which are not, gummy or fibrous used for preparing coal sample for calorific tests. Mortars revolve and pestle moves back and forth in a pattern reaching all parts of the motor. It has adjustable posts to hold mortar 75 to 135 diameter and arm of pestle driving mechanism has hinged, weighted head which can be raised to inspect or remove sample and additional weights may be added to the head if designed. Built in timer permits selection of grinding operation up to 60 minutes. Timer has hold position for continuous, untimed operations and 75mm agate pestle mortar. Operates on 220V 50 c/s AC. $744

With 100 mm agate pestle mortar (description as above). $915