76 ANNUAL OF SCIENTIFIC DISCOVERY. 



words, round its circumference; the ivory is then ?tcnmed, nnd flattened 

 under hydraulic pressure, and finally mounted with caoutchouc on a mahog- 

 any panel. 



Enamel painting has the great recommendation of being perfectly inde- 

 structible. Specimens of this art applied to pottery are now in existence 

 which have not changed their hues during three thousand years. The 

 enamel tints on Egyptian idols, scarabei, necklaces, etc., are precisely sim- 

 ilar to the colors now produced by the enameller. The difficulty of hand- 

 ling the brush is quite as great as in painting on ivory. But a far greater 

 technical difficulty is that of calculating the exact effect of the process 

 of firing the enamel, in altering the hues of the several applications of 

 color. Fine coloring is therefore rai-ely found in enamels. Moreover, the 

 enamel painter's list of pigments is limited to those prepared from metallic 

 oxides, and many metals are perfectly useless on account of the high degree 

 of heat to which enamel paintings are subjected. Modern science has, how- 

 ever, done much to supply this deficiency. The colors are mixed with oil 

 of spike or lavender, or with spirits of turpentine. These essential oils 

 volatilize rapidly under the effect of heat, but the fixed oils would cause the 

 enamel to blister. The ordinary brushes of the painter in water colors are 

 used. 



We extract the following valuable remarks on enamel painting, and 

 account of the process employed by the artists of the present day, from a 

 communication to the Art Journal., in 1859, by an enamel painter of reputa- 

 tion. He says : " Pictures in enamel of any importance as works of art 

 have been very rarely produced until within the last eighty or ninety years'; 

 for, although Petitot, in the reign of Louis XIV., drew with exquisite neat- 

 ness, he seldom produced enamels which aimed at more than microscopic 

 finish and accurate drawing of the human head. His works generally 

 measure from about an inch and a half to two inches in diameter, and are 

 usually either circular or oval. It was reserved for modeni times to try a 

 bolder flight, and the result has been that enamel paintings are now pro- 

 duced with every possible excellence in art. The rich depth of Rembrandt 

 and Reynolds can be perfectly rendered, together with ail their peculiarities 

 of handling and texture; and the delicacy of the most beautiful miniature 

 of ivory may be successfully competed with. As regards size, enamels are 

 now painted measuring as much as sixteen inches by eighteen, and fifteen 

 inches by twenty. The kind of enamel used for pictorial purposes is 

 called 'Venetian white hard enamel;' it is composed of silica, borax, and 

 oxide of tin. The following is a brief description of procedure in the art of 

 enameling: 



" To make a plate for the artist to paint upon : A piece of gold or copper 

 (usually gilt) being chosen, of the requisite dimensions, and varying from 

 about an eighteenth to a sixteenth of an inch in thickness, is covered with 

 pulverized enamel, and passed through the fire until it becomes of a bright 

 white-heat; another coat of enamel is then added, and the plate again fired; 

 afterwards a thin layer of substance called flux is laid upon the surface of 

 the enamel, and the plate undergoes the action of heat for the third time. 

 It is now ready for the painter to commence his pictm-e upon. ' Flux' 

 partakes of the nature of glass and enamel: it is semi-transparent, and 

 liquefies more easily in the furnace than enamel. When flux is spread over 

 a plate, it imparts to it a brilliant surface, and renders it capable of receiv- 

 ing the colors; every color, during its manufacture, is mixed with a small 



