256. _To cement Broken China._--Mix some oyster-shell powder with the white of a fresh egg, to the thickness of white paint, lay it on thick at the two edges and join them as exact and quick as possible, then put it before the fire till the china is quite hot, and it will cement in about two minutes. Pour boiling water into it directly, wipe it dry, scrape it clean on both sides with a penknife, and it will appear only as a crack. Mix no more than you can use for one or two things at a time; for if the cement grows hard, it will be spoiled. The powder may be bought at the apothecaries'; but it is best prepared at home, which is done as follows:--Choose a large, deep oyster-shell; put it in the middle of a clear fire till red-hot, then take it out and scrape away the black parts; pound the rest in a mortar as fine as possible; sift and beat it a second time, till quite smooth and fine. 257. _Obs._--In cementing china and glass, first heat the portions, and when the cement is applied, press them closely together, as the thinner the cement is, the more firmly it holds. 258. _To cement Broken China or Glass._--Beat lime to the finest powder, and sift it through fine muslin; then tie some into a thin muslin; put on the edges of the broken china some white of egg; dust some lime quickly on the same, and unite them exactly. 259. _Chinese method of mending China._--Take a piece of flint-glass, beat it to a fine powder, and grind it well with the white of an egg, and it joins china without riveting, so that no art can break it in the same place. You are to observe, that the composition is to be ground extremely fine. 260. _Improved Corks for preserving Wine or Chemical Liquors._--Melt together two parts of white wax and one part of beef suet; dip your corks in this mixture, and immediately dry them in a stove upon an iron plate; repeat this operation twice, and the corks thus prepared will preserve any liquor well without imparting any ill-flavor thereto. 261. _Bottle Cement._--Common red and black sealing-wax, of each half-a-pound; bees'-wax, quarter of an ounce. Melt them in an earthen pipkin or brass kettle. The former is preferable, because the cement may be kept in it, and again melted whenever it is wanted for use. When the mixture begins to froth, and seems likely to boil over, stir with a tallow candle, which will settle the froth. As soon as the whole is melted, it is ready for use. 262. _Bottle Cement._--Melt in an iron ladle some rosin, and a quarter as much bees'-wax; add a little Venetian red, stir with a piece of candle, and, when smoothly melted, dip in the top of the bottles, so as completely to cover them. In making this cement, be careful not to leave it a moment while it is on the fire. 263. _Blood Cement._--Blood Cement, for repairing copper boilers, &c., is made by pounded quick-lime and ox-blood mixed together: it must be applied fresh made, as it soon becomes so hard as to be unfit for use.