650 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
quently as emerald, using the emerald of Limousin, which is nearly 
white because it is free from the chromium oxide present in the green 
emerald used in jewelry; an oxide which is really an impurity. 
To sum up, ceramic decoration in a reducing fire makes it possible 
to obtain effects which are totally unknown in decoration by an 
oxidizing firing. The colors obtained by reduction possess a con- 
siderable power; they are not due to chance, as certain ceramists 
declare, but they are determined by true chemical reactions between 
the metallic oxides and the products of combustion. We have not 
yet mastered them, it is true, for the study of them is only roughly 
sketched out, and if I have been able to determine the exact condi- 
tions under which copper red can be obtained at will it is only the 
result of a considerable number of observations.¢ 
Decoration with a reducing flame offers a vast field for research 
which I believe will reveal some absolutely new facts. 
In this brief study of the evolution of ceramic decoration I think 
I have demonstrated sufficiently the truth of the statement I made 
at the beginning; that is, that this art has been intimately con- 
nected with the history of races since the origin of humanity. 
4T can not enter into all the details of the production of copper red. I have 
recently written an article on this subject which appeared in the Transactions 
of the English Ceramic Society, vol. 8, p. 71 (on the development of copper 
red in a reducing atmosphere). 
