The best material for cleansing either porcelain or glass-ware, is fullers' earth; but it must be beaten into a fine powder, and carefully cleared from all rough or hard particles, which might endanger the polish of the brilliant surface.

1122. In cleaning porcelain it must also be observed that some species require more care and attention than others, as every person must have observed that china-ware in common use frequently loses some of its colours.

1123. The red, especially of Vermillion, is the first to go, because that colour, together with some others, is laid on by the Chinese after burning.

1124. The modern Chinese porcelain is not, indeed, so susceptible of this rubbing or wearing off, as vegetable reds are now used by them instead of the mineral colour.

1125. Much of the red now used in China is actually produced by the anotto extracted from the cuttings of scarlet cloth, which have long formed an article of exportation to Canton.

1126. It ought to be taken for granted that all china or glass-ware is well tempered; yet a little careful attention may not be misplaced, even on that point: for, though ornamental china or glass-ware are not exposed to the action of hot water in common domestic use, yet they may be injudiciously immersed in it for the purpose of cleaning; and, as articles intended solely for ornament may not be so highly annealed as others, without any fraudu lent negligence on the part of the manufacturer, it will be proper never to apply water to them beyond a tepid temperature.

1127. An ingenious and simple mode of annealing glass has been some time in use by chemists. It consists in im-mersing the vessel in cold water, gradually heated to the boiling point, and suffered to remain till cold, when it will be fit for use. Should the glass be exposed to a higher temperature than that of boiling water, it will be necessary to immerse it in oil.

1128. Having thus guarded against fractures, we naturally come to the best modes of repairing them when they casually take place, for which purpose various mixtures have been proposed; and it will here be sufficient to select only those which excel in neatness and facility.

1129. Perhaps the best cement, both for strength and invisibility, is that made from mastic. The process, indeed, may be thought tedious; but a sufficient quantity may be made at once to last a lifetime. To an ounce of mastic, add as much highly rectified spirits of wine as will dissolve it. Soak an ounce of isinglass in water until quite soft, then dissolve it in pure rum or brandy, until it forms a strong glue, to which add about a quarter of an ounce of gum ammoniac, well rubbed and mixed. Put the two mixtures together in an earthen vessel over a gentle heat; when well united, the mixture may be put into a phial and kept well stopped.

1130. When wanted for use, the bottle must be set in warm water, when the china or glass articles must be also warmed, and tie cement applied.

1131. It will be proper that the broken surfaces, when carefully fitted, shall be kept in close contact for twelve hours at least, until the cement is fully set; after which the fracture will be found as secure as any part of the vessel, and scarcely perceptible. It may be applied successfully to marbles, and even to metals.

ll32. When not provided with this cement, and in a hurry, the white of an egg, well beaten with quicklime and a small quantity of very old cheese, form an excellent substitute, either for broken china, or old ornamental glass-ware.

1133. It is also a fact well ascertained, that the expressed juice of gar lie is an everlasting cement, leaving no mark of fracture, if neatly done. 8

1134. These are fully sufficient for every useful purpose but we may stil further observe, in respect to the ce ment of quicklime, that it may be im proved, if, instead of cheese, we substi tute the whey produced by boiling mill and vinegar, separating the curd care fully, and beating up with half a pinl of it, the whites of six eggs, adding the sifted quicklime until it forms a thich paste, which resists both fire and water (See 139, 72, and 254.)