MANUSCRIPTS, Faded, to Restore. One of the methods in use for the restoration of old or faded writing is to expose it to the vapours of hydrosulphate of ammonia (hydrosulphide of ammonium) until the ink becomes darkened by the formation of sulphide of iron. Another consists in carefully washing, or sponging, the faded manuscript over with a weak solution of the ammonic sulphide, and as soon as the characters become legible, soaking it in water so as to remove the remaining sulphide, and then drying it between folds of blotting paper. A third plan, and one attended with less risk to the paper, is to brush over the manuscript with a moderately strong aqueous solution of gallo-tannic acid, to wash with water, and afterwards to dry it at a temperature of about 150° Fahr.
The solution of gallo-tannic acid may be obtained by making a strong infusion of bruised nutgalls in boiling water, and when cold, straining it. Some old and mediæval manuscripts are written in inks made of carbon. To such the above treatment is inapplicable; being suited only to those traced in ordinary writing ink. For parchments the latter method is preferable.
MAPS. These, as well as architect’s and engineer’s designs, plans, sections, drawings, &c., may be tinted with any of the simple liquid colours mentioned under ‘VELVET COLOURS,’ preference being given to the most transparent ones, which will not obscure the lines beneath them. To prevent the colours from sinking and spreading, which they usually do on common paper, the latter should be wetted 2 or 3 times with a sponge dipped in alum water (3 or 4 oz. to the pint), or with a solution of white size, observing to dry it carefully after each coat. This tends to give lustre and beauty to the colours. The colours for this purpose should also be thickened with a little gum water. Before varnishing maps after colouring them, 2 or 3 coats of clean size should be applied with a soft brush—the first one to the back.
MARASCHI′NO (-kēno). Syn. Marasquin,
Fr. A delicate liqueur spirit distilled from a peculiar cherry growing in Dalmatia, and afterwards sweetened with sugar. The best is from Zara, and is obtained from the marasca cherry only. An inferior quality is distilled from a mixture of cherries and the juice of liquorice root.
MAR′BLE. Syn. Limestone, Hard carbonate of Lime; Marmor, Calcis carbonas durus, M. album (B. P., Ph. E. & D.), L. Marbles are merely purer and more compact varieties of limestone, which admit of being sawn into slabs, and are susceptible of a fine polish. White marble is employed for the preparation of carbonic acid and some of the salts of lime. It contains about 65% of lime. Sp. gr. 2·70 to 2·85. The tests of its purity are the same as those already noticed under Chalk.
Marble is best cleaned with a little soap-and-water, to which some ox-gall may be added. Acids should be avoided. Oil and grease may be generally removed by spreading a paste made of soft soap, caustic potash lye, and fullers earth over the part, and allowing it to remain there for a few days; after which it must be washed off with clean water. Or, equal parts of American potash (crude carbonate of potash) and whiting are made into a moderately stiff paste with a sufficiency of boiling water, and applied to the marble with a brush. At the end of two or three days the paste is removed and the marble washed with soap-and-water. Any defect of polish may be brought up with tripoli, followed by putty powder, both being used along with water.
Marble is mended with one or other of the compounds noticed under Cements.
Marble may be stained or dyed of various colours by applying coloured solutions or tincture to the stone, made sufficiently hot to make the liquid just simmer on the surface. The following are the substances usually employed for this purpose:—
Blue. Tincture or solution of litmus, or an alkaline solution of indigo.