Some substances require to be prepared in a particular manner before
they can be powdered, or to be assisted by adding some other body. For
example, camphor powders more easily when a few drops of spirits of
wine are added to it; mace, nutmegs, and such oily aromatic substances
are better for the addition of a little white sugar; resins and
gum-resins should be powdered in a cold place, and if they are
intended to be dissolved, a little fine well-washed white sand mixed
with them assists the process of powdering. Tough roots, like gentian
and calumba, should be cut into thin slices; and fibrous roots, like
ginger, cut slanting, otherwise the powder will be full of small
fibres. Vegetable matter, such as peppermint, loosestrife, senna, &c.,
requires to be dried before it is powdered.