For this purpose eggs which are newly laid should always be chosen, as any decomposition of the contents will, probably, cause a discolouration of the shell. Make a hole at the smaller end, with an awl, or some other pointed instrument, and another at the larger end, which should be as small as possible, merely a pin hole will do; to this latter the mouth must be applied to blow out the contents. If the yolk does not come out readily, get a cup full of water, and immersing the sharp end into it, put your mouth to the blunt end, and suck up some of the water into the shell, then shake it about well, and blow it out again; repeat this operation two or three times, if necessary. If the shell has got soiled in any way, wash it well in strong lather, using a nail-brush if the stains do not come off readily, but great care must be taken in the handling of so brittle and fragile an article. Now as the membrane which lines the shell would be likely to decompose, and render it offensive, if not injure its beauty, it is best to wash the inside with a solution of the bichloride of mercury, commonly called corrosive sublimate, in spirits of wine; this solution should be prepared by a chemist, and used with great caution, as it is extremely poisonous. Pour it into a wineglass, and holding the egg firmly, yet tenderly, with the finger and thumb, which should not touch the liquid, put the smaller end therein; then apply the mouth, as previously directed, to the larger end, and suck up gently; cease doing so as soon as you are aware, by a cold sensation in the finger and thumb, that the liquid has entered the shell, which then take up by the two ends, so as to stop the orifice, and shake it well, then blow the solution back into the glass, taking care to wash the lips or the fingers if it comes in contact with either of them. The Oological specimen will soon dry, and is now ready for the cabinet. To render it more glossy and brilliant, it may have a coat of mastic varnish, put on thinly with a camel-hair brush, or, if the egg be of a blue or green tint, as many are, a solution of very pure white gum arabic is best, as the varnish is apt to injure those delicate colours.