1007.] on Conservation of Historic Buildings and Frescoes. 605 



by taking -i parts by weight and melting them in the presence of 

 1 part of terpene and 16 parts of tokiol. The mixture is spread on 

 the stone, and then, after the lapse of 24 hours at least, the residual 

 layer of ceresin is driven by heat into the stone. There results a 

 slight deepening of the colour of the surface and a slight marble-like 

 translucency. These changes of tone and colour may be seen on 

 Mercers' Hall by comparing the untreated, the baryta- treated, and 

 the double-treated parts. Ceresin produces a better result than the 

 more crystalhne paraffin of the same solidifying point, though the 

 latter is perhaps less liable to be soiled by smoke. It is essential to 

 the success of the double treatment that the calcium hydrate set free 

 by the baryta should be allowed time to become carbonated before 

 the ceresin-paste is applied. The advantage of associating the two 

 treatments lies in this, that while the baryta repairs the damage done 

 by sulphuric acid and reconstitutes the stone structurally, the ceresin 

 waterproofs the surface and prevents further corrosion. Needless to 

 say, it is wiser to waterproof a sound rather than a crumbling stone 

 What Sir Gilbert Scott tried to do in Westminster Cloisters, with his 

 very perishable so-called preservative, shellac in spirit, was the latter, 

 and led to unhappy results. Thus even ceresin or paraffin cannot be 

 always recommended, notably where soluble salts and moisture are 

 present. To coat the outer weak layer of stone-work decayed to 

 some depth tends to form an easily detachable crust. 



However, ceresin alone has been used with apparent success so 

 far in the case of the local Camaru stone of which the Bank of 

 Australasia at Melbourne is built. After due laboratory experiments 

 I recommended this treatment in February l'J()3. Mr. Anketell 

 Henderson, the Melbourne architect, tried aluminium oxalate and 

 other solutions, but found, he says, " that ceresin alone resisted the 

 wet of our torrential rains and the erosion of our sand-storms." He 

 emphasises the use of a ceresin of high melting-point to obviate 

 tackiness, and employs an electric heater in his spraying apparatus. 

 Ordinary oil-paint, frequently renewed, fails to preserve the stone in 

 question. Even a solution of ceresin in petrol proved too weak. 



We will now turn to the conservation of mural paintings. Besides 

 ordinary oil-painting four methods are or were in common use — 

 tempera or distemper, true fresco, stereochrome or water-glass, and 

 the so-called spirit fresco of the late Mr. Gambler Parry. The last- 

 named process or method need not detain us, for, so far, the paintings 

 executed in this way, if the ground or plaster have been properly 

 prepared and protected, require nothing further than cleaning with 

 bread. And if they should suffer injury or need further protection, 

 the diluted medium can be used for these purposes. Owing to causes 

 explained in memoranda addressed to H.M. Office of Works, the 

 two well-known lunettes by Lord Leighton (Arts of Peace, 1881-6, 

 and Arts of War, 1870-80) in the Victoria and Albert Museum, 

 have required cleaning and repairing in the manner indicated. But 



