(1) Warm the stone till an ordinary copper etcher's etching-ground will become so fluid on it that it can be worked with a leather ball like a varnish, and can be spread very thin and very evenly. Great care must be exercised lest uneven warming crack the stone. If one can put it into a nearby baker's oven, it will obviate the necessity for an especial apparatus, which otherwise is demanded. After coating the stone with the etching-ground, it is reversed while still warm, and blackened by applying the flame of a tallow or wax candle, as the copper-plate etchers do with their plates. Then the stone is set aside to cool, with great precautions against dust. After it is cool, dust will not harm it, and it can be kept indefinitely before use, so long as the coating is protected against injury. (2) The method given is the best; but if the warming of the stone is difficult, there is a method applicable to cold stones. The etching-ground is dissolved in oil of turpentine and laid on the stone with a clean ball. A stone so treated must be put away for at least a day in a place safe from dust that the oil of turpentine may evaporate. To tint this etching-ground, it may be blackened by smoking with a candle, as in the first case; or color, such as lampblack or vermilion, may be mixed-in before it is applied. If one wishes to be very certain that the stone will bear the etching well, it may be coated, very thinly indeed, with a solution of very firm chemical ink after applying the etching-ground. The design is traced through this coating to the stone. It may be transferred, also, but in that case, as soon as the transfer is on the stone, it must be coated thinly once more with a solution of chemical ink that does not, however, contain any lampblack or other coloring-matter, but is transparent. This is necessary to fill out any little holes and other injuries that may have been caused by the pressure during transfer or by the inequalities in the transfer paper. The designing with the needle is done as in the engraved manner, except that the design is merely cut into the coating. When the design is complete, the stone is laid into the etching-trough and diluted aquafortis, muriatic acid, or strong wine vinegar is poured over it repeatedly, according to the depth that the lines are to have.