648 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
with metallic luster. To obtain these scintillating deposits, whose 
process of manufacture I have described several times, it is only 
necessary to apply to the glaze after it is fired a copper salt—oxide 
sulphide, oxalate, or the like. The piece is then heated to a dull red 
(about 550°) and afterwards submitted to the action of reducing 
cases. These iridescent tones may be varied by the addition of salts 
of silver and bismuth, but I have previously shown that the brown, 
yellow, golden, or red shades of metallic deposits are not due, as here- 
tofore believed, to the nature of the mixture of oxides, but to the 
duration of the reduction. 
The copper red, called rouge, flammé, or flambé, is fired in a reduc- 
ing flame, not at a low but at a high temperature. At the present 
time, it is true, the public has been so misled by ceramic fairy tales 
that they are completely ignorant as to what these flamed pieces are. 
Asa matter of fact, when a particular vase has little value, and is conse- 
quently difficult to sell, they embellish it with the description “ flammé 
de grand feu” (flamed at a high temperature), demand quadruple 
the actual worth, and almost always then find a purchaser. Every- 
one seems to possess a peculiar mentality that leads him to see some- 
thing wonderful in the simplest things. He is easily led astray by 
these ceramic fables, for the art to him is secret, of fearful tempera- 
tures, and of mysterious manipulations worthy of the most somber 
epochs of the middle ages. These fables are a relic of Bernard 
Palissy, who had better never have written his Art de terre. 
Many imagine that these flame effects can not be obtained except 
on stoneware. This is again an error; they are even more beautiful 
on porcelain on account of the whiteness of the clay. 
The term flammé applies exclusively to that beautiful red finish, 
with a copper base, which generally shows vertical striations due to 
the variable intensity of the coloring material. These variations of 
tone are a result of the action of the reducing gases, which contain 
zones in the interior of the kiln which are not all saturated in the 
same degree with carbon dioxide or hydrocarbons. This is clearly 
indicated by the fact that on a vase colored with this copper red are 
frequently found greenish or bluish parts, and sometimes even pal- 
pable greens or blues showing an oxidizing action, and brown and 
black parts produced by a more intense reduction than that causing 
the vivid reds. These peculiarities show that there evidently exist 
varied zones in the kiln, some oxidizing, some neutral, and some 
reducing, the latter of course being the preponderating element. 
These rouge flammé coverings may be either brilliant or mat; the. 
former, however, are incomparably more beautiful than the latter. 
To obtain a mat red a large proportion of alumina (in the form of 
kaolin) or lime (in the form of chalk) must be introduced into the 
