Table 123

In the case of roses and other flower petals the loss and deterioration are so serious that the effort is always made to distil them as soon as possible after gathering.

When drying is resorted to it must not be carried to excess, since this tends to make the material friable and causes consequent loss in handling, this being particularly the case with peppermint.

Fig. 189.

Igranic Electric Co., Ltd., Bedford.

This diagram illustrates the operation of a magnetic separator pulley. Non-magnetic material is projected heyond the pulley while magnetic material is held in contact with the conveyor belt until the latter passes under the pulley.

When grinding, cutting, or otherwise reducing raw material to a condition suitable for distillation, considerable danger exists on account of the possible presence of stray iron, usually in the shape of nails, screws, or bolts. Two dangers are present, the first through the possible and generally costly damage to the machine, and the second through explosive ignition of the material under treatment, especially if this be dry or if it have a high content of essential oil. The use of a magnetic device for removing the iron is highly desirable and is now being widely practised. The most suitable form is that of a magnetic pulley, the action of which is shown in Fig. 189.1 The magnetising of the pulley is accomplished by the passage of a direct electric current through the windings in the interior of the pulley. Any iron or steel is attracted by the pulley and is held in contact with the belt until the latter leaves the pulley underneath ; it then drops clear of the other material, which is projected beyond the pulley.

1 By kind permission of Messrs. The Igranic Electric Co., Ltd., Bedford.