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.