ENAMELS 



273 



it should be charged with less enamel, as, when exposed to heat, the enamel draws up 

 the gold to itself, and makes the piece convex. When the enamel is not to cover the 

 whole plate, it becomes necessary to prepare a lodgment for it. With this view, all 

 tho outlines of the figure are traced on the plate with a black-lead pencil, after which 

 recourse is had to the graver. 



Tho whole space enclosed by the outlines must be hollowed out in bas-relief, of a 

 depth equal to the height of the fillet, had tho plate been entirely enamelled. This 

 sinking of tho surface must be done with a flat graver as equally as possible ; for if 

 there bo an eminence, the enamel would bo weaker at that point, and the green would 

 appear. Some artists hatch the bottom of the hollow with close lines, which cross 

 each other in all directions ; and others make lines or scratches with the edges of a 

 file broken off square. The hatchings or scratches lay hold of the enamel which might 

 otherwise separate from the plate. After this operation, the plate is cleansed by 

 boiling it in an alkaline lye, and it is washed first with a little weak vinegar, and 

 then with clear water. 



Tho plate thus prepared is to be covered with a coat of white enamel, which is done 

 by bruising a piece of enamel in an agate or porcelain mortar to a coarse powder, like 

 sand, washing it well with water, and applying it in the hollow part in its moist state. 

 The plate may meanwhile be held in an ordinary forceps. The enamel powder is 

 spread with a spatula. For condensing the enamel powder, the edges of tho plate are 

 struck upon with a spatula. 



Whenever tho piece is dry, it is placed on a slip of sheet iron perforated with 

 several small holes (see fig. 825), which is laid on hot- cinders, and left there 



825 



until it ceases to steam. It must be kept hot till it goes to the fire ; for were it 

 allowed to cool, it would become necessary to heat it again very gradually at the 

 mouth of the furnace of fusion, to prevent the enamel from decrepitating and flying 

 off. 



Before describing the manner of exposing the piece to the fire, we must explain 

 the construction of tho furnace. It is square, and is shown in front elevation in fig. 

 826. It consists of two pieces, the lower part A, or the body of the furnace, and tho 

 upper part B, or the capital, which is laid on the lower part, as is shown in fig. 827, 

 where these two parts are separately represented. The furnace is made of good fire- 

 clay, moderately baked, and resembles very closely the assay or cupellation furnace. 

 Its inside dimensions are 9 inches in width, 13 inches in height in the body, and 9 ia 

 the capital. Its general thickness is 2 inches. 



The capital has an aperture or door, c, fig. 826, which is closed by a fire-brick 

 stopper m, when the fire is to be made active. By this door fuel is supplied. 



The body of the furnace has likewise a door D, which reaches down to the pro- 

 jecting shelf E, called the bib (mentonniere), whose prominence is seen at E, fig. 826. 

 This shelf is supported and secured by the two brackets, F, F ; the whole being of 

 earthenware. The height of the door D, is abridged by a peculiar fire-brick G, which 

 not only covers the whole projection of the shelf E, but enters within the opening of 

 the door D, filling its breadth, and advancing into the same plane with tho inner 

 surface of the furnace. This plate is called the hearth; its purpose will appear 

 presently ; it may be taken out and replaced at pleasure, by laying hold of .the handle 

 in its front. 



VOL. II. T' 



