44-4 Mr. A. Essex's Account of the 



fectly transparent glass. When a small quantity of oxide 

 either of gold, silver, cobalt, copper, or some few others 

 of the metals is added to this base it produces a coloured 

 transparent enamel. This enamel is used on silver and gold, 

 and is applied to the ornamenting of snuff-boxes, watch-cases, 

 and various articles of jewellery. Previously to the applica- 

 tion of the enamel, various patterns and devices are bright- 

 cut in the metal with the graver or the rose-engine, and the 

 cuts, reflecting the rays of light from their bright and nu- 

 merous surfaces, exhibit through the richly coloured enamels 

 a beautiful and gorgeous play of colours sparkling in varied 

 forms with every change of aspect. Sometinies this enamelled 

 bijouterie is further adorned with paintings in enamel, execu- 

 ted on rich transparent grounds, when, in some ijistances, a 

 sunlike splendour is imparted to the whole scene by the rays 

 of the engine-turned gold shooting from behind the moun- 

 tains in a landscape, or diverging from the bosom of a lake. 

 The enamel which, when painted upon, produces the most 

 agreeable effect in these applications, is that which is opal- 

 escent, and which by enamellers is called opal; the soft cream- 

 coloured and fiery appearance of the gem being imparted in 

 this imitation by the oxide of arsenic. 



When oxide of tin or of antimony is added to the transpa- 

 rent base mentioned above, the result is an opake enamel. 

 I suspect, but am not certain, that oxide of antimony enters 

 into the composition of some of the Venetian enamels. 1 have 

 made an enamel with it alone, as the colouring matter, whiter 

 than some specimens of foreign manufacture, and having in a 

 high degree the waxlike appearance formerly so much valued 

 by the makers of enamel clock- and watch-tiial plates. But 

 oxide of tin is certainly the substance to which opake enamel 

 commonly owes its opacity and whiteness*. 



The enamel used for making the plates upon which paint- 

 ings in enamel are executed is imported from Venice. It is 

 in the form of round cakes, varying in size from three to seven 

 inches in diameter, and from half to three quaiters of an inch 

 in thickness, and weighing from half a pound to three pounds 

 each. It is cream-coloured, heavy, less brittle than glass, is 

 sufficiently hard to scratch crown-glass ; its fracture is con- 

 choidal and exhibits a resinous lustre, and it fuses at a tem- 

 perature a little below that which will melt gold. Its com- 



« There is a substance made at the glass-houses near I^ondon, the coni- 

 merciai name of which is glass- enamel^ that owes its measure of opacity 

 and whiteness to the oxide of arsenic. It is very glassy, brittle, easily 

 scratched, readily fusible, and very white. It is used for making the com- 

 mon kinds of clock- and watch-dials and the white semi-opake ornanients 

 for the mantel-i;heU, toilet, &c. 



