_To make Paper Waterproof._—Dissolve 8 oz. of alum and 3⅓ oz. of white soap in 4 pints of water. In another vessel dissolve 2 oz. of gum-arabic and 4 oz. of glue in 4 pints of water. Mix the two solutions and heat them over the fire. Then immerse the paper, sheet by sheet, in the hot liquid, then hang them up edgewise to dry, or pass them between heated cylinders. * * * * * _Books Preserved._—The bindings may be preserved from mildew by brushing them over with the spirits of wine. A few drops of any perfumed oil will secure libraries from the consuming effects of mould and damp. Russia leather, which is perfumed with the tar of the birch tree, never moulds or sustains injury from damp. The Romans used oil of cedar to preserve valuable manuscripts. Russia leather covered books placed in a stationer’s window will destroy flies and other insects. * * * * * _To restore Engravings, etc._—Old engravings, wood-cuts, or printed matter, that have turned yellow, may be rendered white by first washing carefully in water containing a little hyposulphite of soda, and then dipping for a minute in Javelle water. To prepare the latter, put 4 lbs. bicarbonate of soda in a kettle over a fire; add 1 gallon of boiling water, and let it boil for fifteen minutes. Then stir in 1 lb. of pulverized chloride of lime. When cold, the liquid can be kept in a jug ready for use. [Illustration] ORTHOGRAPHICAL. A thorough reformation of the orthography of the English language, desirable as it is, can scarcely be hoped for in this century; though doubtless the time will come when an international convention will settle authoritatively the spelling of every word, as acceptably as has been done by the Academies of France and Spain in regard to the orthography of the languages of those countries. _A or AN before a Vowel or silent H._ In regard to the use of the indefinite article, Walker’s Dictionary very judiciously says,—