On the Art of Glass-Painting. 457 



attention, and many attempts were made to revive it. It was 

 soon found by modern artists, that by employing the pro- 

 cesses always in use among enamel-painters, the works of the 

 old painters on glass might in most respects be successfully 

 imitated ; but they were totally unable to produce any imita- 

 tion whatever of that glowing red which sheds such incom- 

 parable brilliancy over the ancient windows that still adorn 

 so many of our churches *. For this splendid colour they 

 possessed no substitute, until a property, peculiar to silver 

 alone among all the metals, was discovered, which will pre- 

 sently be described. The art of enamelling on glass differs 

 little from the well-known art of enameUing on other sub- 

 stances. The colouring materials (which are exclusively me- 

 tallic) are prepared by being ground up with a Jinx, that is, 

 a very fusible glass, composed of silex, flint-glass, lead, and 

 borax: the colour with its flux is then mixed with volatile oil, 

 and laid on with the brush. The pane of glass thus ena- 

 melled is then exposed to a dull red heat, just sufficient to 

 soften and unite together the particles of the flux, by which 

 means the colour is perfectly fixed on the glass. Treated in 

 this way, gold yields a purple, gold and silver mixed a rose- 

 colour, iron a brick-red, cobalt a bluet; mixtures of iron, 

 copper and manganese, brown and black. Copper, which 

 yields the green in common enamel-painting, is not found to 

 produce a fine colour when applied in the same way to glass, 

 and viewed by transmitted light; for a green therefore re- 

 course is often had to glass coloured blue on one side and 

 yellow on the other. To obtain a yellow, silver is employed, 

 which, either in the metallic or in any other form, possesses 

 the singular property of imparting a transparent stain, when 

 exposed to a low red heat in contact with glass. This stain 

 is either yellow, orange, or red, according to circumstances. 

 For this purpose on flux is used : the prepared silver is merely 

 ground up with ochre or clay, and applied in a thick layer 

 upon the glass. When removed from the furnace the silver 

 is found not at all adhering to the glass ; it is easily scraped 

 off, leaving a transparent stain, which penetrates to a certain 

 depth. If a large proportion of ochre has been employed, 

 the stain is yellow; if a small proportion, it is orange-coloured; 

 and by repeated exposure to the fire, without any additional 



• In 1774 the French Academy published Le Vieil's treatise on Glass- 

 painting;. He possessed no colour approaching to red, except the brick- 

 red or rather rust-coloured enamel subsequently mentioned in the text, de- 

 rived from iron. 



f It appears by^a boast of Suger, abbot of St. Denis, which has been 

 preserved, that the* ancient glass-painters pretended to employ sapi)hires 

 among their materials ; hence, perhaps, the origin of the term Zaffra, 

 under which the oxide of cobalt is still known in commerce. 



Third Series. Vol.9. No. 56. Dec. 1836. 3 I 



