3()4 REPORT OF NATIONAL MUriEUM, 11)00. 



of iron, the amount of that metal and the nature of the ga.s .surromiding 

 the vessel in the kihi determining the tone of the color from a light 

 shade to one resem))ling bronze, and warmth of color being obtained by 

 an oxidizing atmosphere. Blacl- grounds are produced in a variety of 

 ways, either by the thickness of the colored glaze, or by laying several 

 shades of different colors one on the other, or, again, bj^ laying a blue 

 glaze on a brown laque, or vice v<irs((. 



M. Salvetat writes that among the colors for the ground employed 

 in China some are evidently applied upon the biscuit; that is, porce- 

 lain already lired at a high temperature. These are violet, turquoise 

 hive, yellmv, and green, all containing a pretty large proportion of 

 oxide of lead; and, vitrifying as they do at a medium temperature, 

 hold a place half way between the two main categories and may be 

 therefore termed colors du demi-grand feu. Nothing approaching 

 these colors, he says, is produced in Europe. To do so, however, 

 would not be difficult, the green and turquoise blue owing their colors 

 to copper, the yellow^ to lead and antimony, and the violet to an oxide 

 of manganese containing but little cobalt. 



Colors de moufle. — In Europe these colors are obtained by mixing 

 one oxide or several metallic oxides together with a vitreous flux, the 

 composition of which varies with the nature of the color to be devel- 

 oped. That most generally used is termed " the flux for gra3's.'" It 

 serves not only for grays, however, but also for blacks, reds, blues, 

 and 3^ellows, and is composed of six parts of minium, two parts of sili- 

 cious sand, and one part of melted borax. The colors are obtained by 

 mixing by weight one part of metallic oxide with three parts of the 

 flux, so that the composition may be expressed thus: 



Silica 16. 7 



Oxide of lead 50. 



Borax , . . . 8. 3 



Coloring oxides 25. 



100. 



In cases w^here, as with oxide of cobalt, the colors are produced by 

 mixture with the flux and ought to have the required shade when 

 applied, the metallic oxides are melted with the flux prior to use; in 

 those, however, where the desired color is that inherent in the oxide, 

 the tone of which would be changed b}" a double exposure to fire, as is 

 the case with reds derived from iron peroxide, the union with the flux 

 by melting is dispensed with. The colors so made suffice to permit 

 the reproduction on porcelain of oil paintings; but it is essential that 

 they all melt at the same temperature and after baking present a suffi- 

 cient and thoroughly uniform glaze. 



In Chinese decorations these conditions, insisted upon in Europe, 

 are both absent. Some colors, such as the rose tints derived from gold, 

 the blues, greens, and yellows, are brilliant, thoroughly melted, and so 



