Printing from line-engraved plates is largely done by hand presses. The ink used is very thick. When black it is made of finely pulverized carbon, mixed with oil. Colored inks are composed of zinc white and dry colors, ground in oil. The colors are animal, vegetable or mineral. The latter cause the plates to wear out rapidly. Green is an especially destructive color. In recent years aniline colors have been largely employed. They afford an elaborate range of shades and color combinations which are most puzzling to describe. Soluble inks are much used by the leading English firm of stamp printers. They are very sensitive to water and are regarded as one of the best preventatives of the cleaning of used stamps. Beautiful results are obtained by printing stamps in two colors. Of course, this necessitates the use of two plates for each design. This also gives rise to some interesting varieties, caused by one part of the design being printed upside down. Such oddities are scarce and are highly valued by philatelists. When a plate is to be printed from, it is first warmed, then the ink is applied and rubbed into the lines with a pad. The surface of the plate is wiped off with a cloth, then with the hand and lastly, polished with whiting. A sheet of dampened paper is next laid on the plate and the whole is passed under the roller of a press, which forces the paper into the lines of the plate, where it takes up the ink. When the plate is deeply engraved the ink seems to stand up from the surface of the paper in ridges and some times we find corresponding depressions on the backs of the stamps. The sheets are then dried, gummed and dried again. They are now so much curled and wrinkled that they are placed between sheets of bristol board and subjected to hydraulic pressure of several hundred tons which effectively straightens them out. The second process of printing from metallic plates is called typography. The plates for this process are the exact reverse of those engraved in _taille douce_. Instead of the design being cut into the plate, it is on the surface and everything else is cut away. Hence, the term "surface printing." This form of engraving is also called _epargne_ engraving, because the parts of the plate which bear the design are _epargne_ (preserved.)