ASTIFICIAL EOCKWOKK, ETC. 241 



"break up the appearance of shelves, and to give a certain 

 homogeneity, was then treated by having brown paper well glued 

 on both sides, stuck all over the edges, joins, or accidental 

 fissures; this, suffered to dry, was then well painted with a 

 mixture of whiting and glue-water, again allowed to dry, and 

 again painted. "When this last was dry it was gone over with 

 a thin wash of glue-water, and sharp " silver " sand thrown on ; 

 when dry, coloured by staining it with various oil colours (not 

 tube), and some few powder colours — blue-black, yellow ochre, 

 Yandyke brown, celestial blue (cheap), burnt sienna, &c., thinned 

 with turps, afterwards touched up, when dry, with touches of tube 

 colours, smartly and cleanly put on. This would be the treat- 

 ment and colouring for greyish-brown or yellowish-grey smooth, 

 dry-looking rocks, sandstones, &c. ; and by a little alteration of 

 tint and treatment in places, would imitate the various slates. 



For chalk and limestone, mix plaster and sand with the 

 whiting and lay it on thickly, not throwing on sand, as a final 

 operation. Colours, of course, are different here, more bright 

 and light green predominating ; but the colouring of the 

 rockwork, &c., to imitate the various kinds of rocks required, 

 is only to be learned by experience ; in point of fact, to colour 

 rocks in an effective manner is really the work of an artist, 

 for it is requisite to know the properties of colours, and to 

 " scumble " and " stipple " or " glaze " one colour over another 

 to get " depth." A few hints may, however, help out the tyro. 



For rough sea rocks, after sanding and glueing, go over the 

 rockwork with a mixture of chrome yellow and Prussian blue, 

 mixed with oil and tui^ps, the blue predominating; touch up 

 the points with white, and allow it to dry. The next day 

 deepen the shadows with Brunswick black, " stippling " lightly 

 the remainder of the rock with the same. Arrange sea-shells 

 and sea -weed, here and there, where the mounted subject 

 allows of this treatment. This is a shining dark bluish-green 

 and brown rock, suitable for sea-gulls, divers, &c. 



For rough grey land rock, paint over all with lamp-black in 

 powder, mixed with plaster of Paris, and touch up the points 

 with oil white. When the work is quite dry, go over all with 

 a glaze of Prussian blue mixed with Brunswick black. Fit 

 up with ferns, grass, and golden lichens on the points, or in 



