675. _To take Impressions of Butterflies' Wings._--Lay the wings gently on paper, wet with gum arabic water, and nearly dry; a copy will be left when the wing is removed, but inferior in beauty to the wing itself. It is better to gum the wings themselves on paper, and paint the body of the fly in its natural position. 676. _To preserve the Eggs of Birds._--First clean them of their contents. This may be done with the larger eggs by making a hole on one side large enough to admit a quill, and shaking out the contents. Then wash them well with a solution of camphor, not too strong, or it will make them brittle. When dry, fasten them with gum on the side in which the hole was made to a piece of card board, and write the name under each. As the colors of many of them are perishable, to preserve them give them a slight coating of varnish. The best varnish for this purpose is isinglass dissolved in gin. In cleaning the smaller eggs, make a hole at each end, a little to one side, and blow them. The camphor solution need not be used. 677. _To make Artificial Coral._--Melt together four parts of yellow resin and one part of vermilion. Dip twigs, cinders or stones in this, and when dry they will resemble coral. 678. _An Excellent Pen-Wiper for Steel Pens._--Fill a short, wide-mouthed vial with shot, the smaller the better. Whenever it is necessary to clean the pen, rub it up and down in the shot. This is much more effectual than cloth wipers, and the shot will last a life-time. 679. _To preserve Steel Pens._--Metallic pens may be preserved from rusting by throwing into the bottle containing the ink a few nails, or broken pieces of steel pens, if not varnished. The corrosive action of the acid which the ink contains is expended on the iron so introduced, and will not therefore affect the pen. 680. _Black Paper for drawing Patterns._--Mix and smooth lamp-black and sweet oil; with a bit of flannel cover a sheet or two of large writing-paper with this mixture; then dab the paper dry with a bit of fine linen, and keep it by for using in the following manner:--Put the black side on another sheet of paper, and fasten the corners together with small pins. Lay on the back of the black paper the pattern to be drawn, and go over it with the point of a steel pencil; the black paper will then leave the impression of the pattern on the under sheet, on which you must draw it with ink. If you draw patterns on cloth or muslin, do it with a pen dipped in a bit of stone blue, a bit of sugar, and a little water, mixed smooth in a teacup, in which it will be always ready for use, if fresh: wet to a due consistence as wanted.