As this work is supposed to be for the use of druggists, no description of weights or measures is thought necessary, nor scarcely a word of explanation, save to observe that when we say ounces or pounds we mean avoirdupois, the weight now officinal in the United States Pharmacopoeia, as well as that used in commercial affairs.

When we speak of grains or drams we mean troy, the weight used universally in our business, for such amounts.

When referring to fluiddrams or fluidounces, we mean fluiddrams or fluidounces, wine measure; likewise, in speaking of pints or gallons.

In writing drops or minims, we will consider the terms interchangeable, as in very small quantities the variation between one and the other would be but trifling, and to drop would be much more convenient.

We have, from practice, found that a book of formulas is not complete unless interleaved. It often occurs that one wishes a smaller or a larger amount than the formula gives, or a slight variation in the proportions of some of the ingredients, for economic or other purposes, may be advisable. In either event, where a permanent memorandum is wished, it is much better to have a blank page attached than a loose leaf, liable to be lost.