424 ENAMELLING. 



form or other, and nitro muri.it of <>U1, and also by the fulminat- 

 iiU ;.old. This l>e;iutiuil rulour iv|irires much skill in (lie artist 

 to be fully brought out. It is said, that when most perfect, it 

 should come from (he fin- quite colourless, and afterwards red iv<; 

 its colour by the Hume of a candle. Cold colours will not bear a 

 violent fire. 



Oth r and common reds are given by the oxyd of iron, but this 

 requires the mixture of alumine, or Borne other substance refrac- 

 tory in the fire, otherwise at a full rod heat the colour will degene- 

 rate into black. 



Yellow is given eilhrr by the oxyd of silver alone, or by the 

 oxyds of lead and antimony, with similar mixtures to those re- 

 quired for iron. The silver is as tender a colour as gold, and rea- 

 dily injured or lo<t in a high heat. 



Green is given by the oxyd of copper, or it may also be pro- 

 cured by a mixture of blue and yellow colours. 



Blue is given by cobalt? and this seems of all enamel colours 

 the most certain, and easily manageable. 



Black is produced by a mixture of cobalt and manganese. 



The reader may conceive how much the difficulties of this nice 

 art are increased, when the object is not menly to lay an uniform 

 coloured glazing on a metallic surface, but also to paint that sur- 

 face with figures and other designs, that require extreme delicacy 

 of outline, accuracy of shading, and selection of colouring. The 

 enamel painter has to uork, not with actual colours, but with 

 mixtures, which he only knows from experience will produce cer. 

 tain colours affer the delicate operation of the tire ; and to the 

 common skill of the painter, in the arrangement of his pallet and 

 choice of his colours, the enameller has to add an infinite quantity 

 of practical knowledge of the chemical operation of one metallic 

 oxyd on another, the fusibility of his materials, aud the utmost 

 degree of heat at which they will retain not only the accuracy of 

 the figures which he has given, but the precise shade of colour 

 which he intends to lay on. 



Painting in enamel requires a succe c sion of firings; first of the 

 ground uliuh is to receive the design, and which ifself requires two 

 firings, and then of the different parts of the design itself. The 

 ground i- hid on in the same general way as the common watch 

 face enamelling already d* scribed. The colours are the different 



