In the preceding five chapters we have, we trust, conveyed to the Student of Lithography a clear idea of the nature and uses of the different materials used in each of the two great divisions of the art—drawing and printing. He is, therefore, prepared now to utilize his knowledge of the materials and to enter upon the practical operations required in this kind of printing.

The stones have been described in the first chapter; the appliances for preparing them in Chapter V.; the modus operandi in the process of preparation now requires to be detailed.

64. Grinding.—As it will fall to the duty of the foreman printer to determine what stones are to be ground, it will be well for him to scratch a cross deeply into the stone, making the scratch deeper in those stones that have been standing the longest with work upon them. This gives the stone-grinder to understand that the cross must be ground out. It is a simple matter that will save the printer's temper and the master's pocket by insuring the thorough grinding of the stones.

It is astonishing to what a depth the stone is affected by the greasy particles of the ink without being perceptibly greasy. The residuum of the ink acts also by preventing an equal absorption of water and gum with the rest of the surface, so that this part, drying soonest and being less protected by gum, favours the spreading of any work that might have been drawn or transferred over it.