action, either physical or chemical; it is really only applied to the modification that takes place before us when we perceive the simultaneous impression of these two colours."
It was not till three years later that a publisher could be found for this book, which is still a standard.
The English translation comprises over five hundred closely printed pages with many engraved and colored plates, and yet, it has been of comparatively little value in popular instruction because of the lack of a generally accepted color nomenclature or list of well defined color terms, by which the readers might have understood and repeated for themselves the experiments described.
Unfortunately Chevreul was fully impressed with the Newton-Brewster idea of three primaries, red, yellow and blue, and therefore some of his deductions from his experiments seem to have been more or less influenced by the attempt to make them harmonize with this theory, and yet the subject which he has treated so exhaustively and intelligently is one of the most important in the aesthetic study and use of colors. In all expressions of colors in combination with each other, whether in nature, fine arts or the decorative and industrial arts, every color is affected by its surrounding colors, a fact which is exhaustively treated in this book.
"While with our present knowledge of the subject it does not seem that the material use of color can be reduced to an exact science, this should not prevent us from accepting all the natural and scientific aids which have been or may be discovered toward this desirable result. Because of this lack of scientific knowledge in Chevreul time much of the worth of his experiments is lost to us, yet there is very much of value in his work, suggesting as it does experiments which may be tried with present standards and modern methods.
If the use of Maxwell disks had been known to Chevreul his deductions from his experiments would have been quite different in their details. For example, in accepting the propo-
