669. Sifting
Sifting is frequently required for powdered substances, and this is usually done by employing a fine sieve, or tying the powder up in a piece of muslin, and striking it against the left hand over a piece of paper.
670. Filtering
Filtering is frequently required for the purpose of obtaining clear fluids, such as infusions, eye-washes, and other medicines; and it is, therefore, highly important to know how to perform this simple operation. First of all take a square piece of white blotting paper, and double it over so as to form an angular cup. Open out this filter paper very carefully, and having placed it in a funnel, moisten it with a little water. Then place the funnel in the neck of the bottle, and pour the liquid gently down the side of the paper, otherwise the fluid is apt to burst the paper.
671. Maceration
Maceration is another process that is frequently required to be performed in making up medicines, and consists simply in immersing the medicines in
cold water