_This Instrument will shew on bare inspection, the quantity of active
matter contained in any given weight or measure (according as it is
solid or liquid) of any Officinal compound, and the dose of any
preparation which will be equivalent in strength to any given
quantity of any other of the same class. The active principles, or
Medicinal Bases, are distinguished by capital letters, placed in
coloured squares; and each Officinal Preparation is marked by a line
corresponding in colour with that of its active ingredient. If we
require the quantity of active matter in any given dose of an
Officinal Preparation, we have only to bring such preparation to the
number in question and the figure opposite the active ingredient
answers the question, while those opposite to the other compounds of
the same class denote the equivalent quantities. Unless otherwise
expressed, the figures denote Grains for the solids, and Minim for
the liquids._
]