Looking-Glass, a plain glass mirror; which, being rendered impervious to light, exhibits the images of such objects as are placed before it, apparently at the same distance behind.

Looking - glasses are made of plate-glass, which is cast and ground in the manner described under the article Glass. When the plates are polished, a fine blotting paper is spread on the table, and strewed over with levigated chalk, which is covered with a thin leaf of tin-foil. Upon the latter is poured the purest quicksilver, that ought to be distributed uniformly over the leaf, with cotton or other soft substance over the mercury, clean paper must be placed ; and upon this, at length, the glass-plate is pressed down by the right hand, while the paper is gently removed with the left. The plate is now covered with a thicker paper, or cloth, and a heavy weight Lid on it, so that the superfluous quicksilver may be expressed, and the tin adhere closely to the glass: when it is sufficiently dry, the weights are taken off, and the work is complete.

Looking-glasses are equally or-mental and useful in domestic life: hence they should not be exposed to accidents, or placed against damp walls, or in other moist situations, where the quicksilver loses its tenacity, and the beauty of the glass will, in a short time, be impaired. - Those idle or conceited persons, who waste every day a certain portion of time, by examining their dress and countenance before a looking-glass, ought to bestow an equal share of attention on their moral scrutiny : thus, we trust, they will easily discover how to make a more proper and economical use of their leisure hours, which are literally killed before a mirror, that exhibits only the surface of things.