On the Art of Glass-Painting. 459 



glass-makers used to Jlash a tliin layer of red over a sub- 

 stratum of plain glass. Their process must have been to melt 

 side by side in the glass-house a pot of plain and a pot of red 

 glass: then the workman, by dipping his rod first into the 

 plain and then into the red glass pot, obtained a lump of plain 

 glass covered with a coating of red, which, by dexterous ma- 

 nagement in blowing and whirling, he extended into a plate, 

 exhibiting on its surface a very thin stratum of the desired 

 colour*. In this state the glass came into the hands of the glass- 

 painter, and answered most of his purposes, except when the 

 subject required the representation of white or ether colours 

 on a red ground : in this case it became necessary to employ 

 a machine like the lapidary's wheel, partially to grind away 

 the coloured surface till the white substratum appeared. 



The material employed by the old glass-makers to tinge 

 their glass red was the protoxide of copper, but on the dis- 

 continuance of the art of glass-painting the dependent manu- 

 facture of red glass of course ceased, and all knowledge of the 

 art became so entirely extinct, that the notion generally pre- 

 vailed that the colour in question was derived from goldf. 

 It is not a little remarkable that the knowledge of the cop- 

 per-red should have been so entirely lost, though printed re- 

 ceipts have always existed detailing the whole process. Bat- 

 tista Porta (born about 1510) gives a receipt in his Magia 

 Naturalis, noticing at the same time the difficulty of success. 

 Several receipts are found in the compilations of Neri, Merret 

 and Kunckel, from whence they have been copied into our 

 EncyclopsediasJ. None of these receipts however state to what 

 purposes the red glass was applied, nor do they make any 

 mention of thejlashing. The difficulty of the art consists in 

 the proneness of the copper to pass from the state of prot- 



lowest ebb, finally extinguished. With regard to our national and ecclesits- 

 tical monuments, we would hope that these niaj- no longer be left at the 

 mercy of chapters and churchwardens, bit put nnder the protection of men 

 of taste and of professional skill empowered to watch over their preservation 

 and to administer the funds devoted to the purpose. — R. T.] 



* That such was the method in use, an attentive examination of old 

 specimens affords sufficient evidence. One piece that I possess exiiibits 

 large bubbles in the midst of the red stratum ; another consists of a stratum 

 of red inclosed between two colourless strata : both circumstances plainly 

 point out the only means by which such an arrangement could be produced. 



+ In 1793, the French government actually collected a quantity of old 

 red glass, with the view of extracting the gold by which it was supposed 

 to be coloured ! Le Vieil was himself a glass-painter employed in the 

 repair of ancient windows, and the descendant o£ glass-painters, yet so 

 little was he aware of the true nature nf the glass, that he even fancied 

 he could detect the marks of the brush with which he imagined the red 

 stratum had been laid on ! 



t [M. Langlois names the following writers : " Neri en 1612, Handicquer 

 de Blancourt en 1667, Kunckel en 16|[9, La Vieil en 1774, et plusieurs 



3 12 



