606 Professor A. H. Church [April 12, 



the long series in the Ambulatory of the Royal Exchange, having 

 been painted on canvas and affixed afterwards to a sound slate 

 backing, have needed no restoration. 



The English mediaeval wall-pictures found chiefly in churches, 

 but not unknown in secular buildings, are commonly but wrongly 

 called frescoes. They were painted on dry plastered walls with pig- 

 ments mixed with size or egg- vehicles. By the mistaken use of 

 varnish, by over-drying when on panel, by mechanical injuries, by 

 vibration, by the chemical action of a corrosive atmosphere, and by 

 the penetration of damp or salts from behind or from below, such 

 paintings have generally suffered serious changes, and are sometimes 

 beyond repair. However, there are several ways of consolidating the 

 painted surface and of securing it in position. Before describing 

 these, and how to choose, in any given case, the most suitable, I 

 would urge the importance of precautionary measures, namely, the 

 disuse of gas, the shutting off from the back and foundation of the 

 wall of all sources of damp, and the avoidance of all further accession 

 of soluble salts, such as nitre, ammonia compounds, Epsom salts, and 

 common salt. 



The very worst preparation that can be applied to a damaged 

 distemper-painting on a damp or saline ground, is a spirit varnish 

 such as mastic or shellac, or an oil varnish such as copal. Where 

 damp and saline matters are present, a dilute solution (under 5 per 

 cent.) of pure gelatin in very weak spirit may be used : spraying 

 with this liquid kept hot is often successful where the pigments are 

 powdery. Another useful liquid is a 7 per cent, solution of casein 

 in very dilute ammonia, containing 1 per cent, of glycerine. This 

 preparation is particularly applicable for the treatment of distemper 

 paintings on wood. But when the works to be treated are on a 

 perfectly dry backing free from injurious saline matters, then, and 

 then only, is it safe to apply what may be called a hydrofuge or 

 waterproofing material to the surface. This we have in the ceresin- 

 paste already described. Occasionally an extremely small addition of 

 copal varnish to this vehicle may be allowed to secure transparency. 

 Indeed, in my earlier operations of this character I have used 

 Gambler Parry's spirit fresco medium, leaving out the elemi, and 

 replacing the beeswax by paraffin or ceresin. But wherever possible 

 nothing but ceresin-paste or ceresin in solution should be employed. 

 i\.fter the cleansing of the surface by an air-blast, by spirits of wine 

 and by bread-crumb, necessary repaints should be executed with 

 powder-pigments mixed with egg-^ yolk : then the ceresin should be 

 applied. Pigments to be avoided are yellow ochre, raw sienna, terre 

 verte, and ivory black : zinc white should replace flake w^hite. 



With regard to the care of water-glass or stereochrome paintings, 

 my experience, confined chiefly to those in Westminster Palace, 

 has been described in full detail in three Parliamentary Papers, 

 Cd. 7651/1895 ; Cd. 8054/1896 ; and Cd. 8893/1898. In these 



