i^O Mr. A. Essex's Account of the 



different instances, and oxide of lead in six, and except one 

 instance of introduction of the former substance, and two of 

 the latter, the artist must of necessity be ignorant of the pro- 

 portions in which they exist in the artificial compounds which 

 he employs. Foreign substances also are present, such as 

 iron, manganese, &c., which, altliough in minute quantities, are 

 injurious and create confusion. These are not noticed in the 

 foregoing analysis, because their introduction or omission, as 

 likewise their proportions when introduced, are dependent 

 upon accident and the pleasure of the manufacturer. 



Let us now proceed to contrast this complex process with 

 the result which some attenticm to the progress of chemical 

 science has enabled the enameller of the present day to arrive 

 at. The following are at once the materials and substantially 

 the constituents of the green enamel colour which Mr. W^ 

 Essex has in use : 



Silica. 



Borax. 



Oxide of lead. 



Oxide of chromium. 

 Here the simplicity is such that all the substances which 

 enter into the composition of the colour are known to the 

 maker, and the proportions in which they shall exist are en- 

 tirely within his command. 



The enamelling- furnace, in which the smaller plates are pre- 

 pared and the smaller paintings also Jired, is a square space of 

 about twelve inches in height, in depth, and in width, surroun- 

 ded by solid brickwork, and opening into a vertical flue in which 

 is a register for regulating the heat. It is elevated a convenient 

 height from the ground, and has an iron plate hearth in front 

 for the purpose of holding the plates and paintings both before 

 and after they have passed through the fire. The bottom of the 

 furnace, when prepared for use, is covered to about three 

 inches in thickness with coke%upon which the muffle is placed. 

 The nmffle has neither bottom nor back, and is surrounded 



• The old enamel painters had a notion that no fuel but charcoal was 

 suitable for an enamelling furnace. The late Mr. Hone held this opinion^ 

 and the late Mr. Grimaldi frequently had fires made with charcoal alone 

 for his paintings, because, as was imagined, the colours '• came out bet- 

 ter;" but I never could discover that those paintings which were treated 

 with charcoal displayed any superiority over those which were fired with 

 coke. In conjunction with Mr. Muss I made several experiments to test 

 the truth of this notion, and these proved it to be fallacious. Coke is by 

 much the more convenient substance, as its combustion is slower, and con- 

 sequently the heat can be maintained without interruption for a longer time 

 by its means than with charcoal, than which it is also very much cheaper. 



