Page:Brinkley - China - Volume 1.djvu/361

 POLYCHROMAHV?C GLAZES

seen conditions of temperature. But that they were also manufactured intentionally scarcely admits of question. M. Jacquemart, writing on the subject of Yao-pien, or flambé, ware, says: —“ As for the cause of the transmutation, modern science knows it so well that each of its effects can be obtained with certainty in the laboratory. Metals change their condition and appearance according to their combi- nation with oxygen. Thus, to confine ourselves to the question under consideration, oxydised copper gives a beautiful red vitrifiable enamel, which, thrown en masse on the surface of a vase, forms the tint called haricot. With another equivalent of oxygen, it be- comes protoxide, and produces a beautiful green, capable of being changed into celestial blue when the oxygenation is pushed a little farther. Now these various combinations can be accomplished suddenly in the kiln by bold tours de main. When a clear fire, placed in a quick draught, draws in a large volume of air, all the oxygen is not consumed, and a portion can enter into combination with the fusing metals. If, on the other hand, there be passed into the oven thick smoke whose carbonaceous mass, thirsting for oxygen, absorbs everywhere this gas essential to com- bustion, the oxides may be destroyed and the metal completely restored. Subjected at a given moment to these different conditions by the rapid and simul- taneous introduction of currents of air and sooty vapours, the Aaricot glaze assumes at last a most pic- turesque aspect. Veined colours, changing, capricious as the flames of alcohol, diaper the surface; the oxy- dised red, passing by violet to pale blue and green protoxide, even disappears completely on salient points which have become white, and thus fur-

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