456 MICHEL EUGENE CHEVREUL. 



and so between blue and red, and between red and yellow. In addi- 

 tion to this "normal" circle, he had eight others, the colors of which 

 were toned down, respectively, with one tenth, two tenths, three 

 tenths, and so on, of black. In order to compare shades of colors, he 

 prepared standard rows, or columns, by mixing liis normal colors with 

 one tenth, two tenths, and so on, of black in one direction, and with 

 one tenth, etc. of white in the other. Chevreul's idea was that stan- 

 dard circles of color should be kept in the custody of public officers, 

 just as standards of weights and measures are kept. But in seeking 

 to carry out this scheme a grave difficulty is encountered in that most 

 colors speedily fade. Moreover, while it is comparatively easy to 

 compare colored threads with the colors of a circle made in silk or 

 woollen, it would not be easy to compare colored woollen stuffs with 

 the colors of a circle made of porcelain ; that is to say, the varying 

 lustres of colors, according as they have been put upon one or another 

 kind of material, hinders very decidedly the accurate comparing of 

 them. It is in fact difficult to compare the colors of metals or alloys 

 with those of dyes fixed upon wool, or of pigments printed on paper. 

 In the course of his lectures, Chevreul was accustomed to construct 

 with skeins of worsted upon the floor of the great exhibition hall at 

 the Gobelins a mammoth circle, which was an object of great beauty. 

 It carried conviction to his audience that the device would be one of 

 great practical utility, if it were but possible to obtain permanent 

 colors with which to construct the circle. 



It was in 1832 that Chevreul printed his first paper on the har- 

 mony of colors, and his book upon tlie subject was published seven 

 years later, when he was fifty-three years old. He continued to 

 write about the contrast of colors as long as he lived ; but not with 

 his old-time sagacity. It must be said, indeed, that, in spite of his very 

 long life, the term of. Chevreul's useful working years was practically 

 no longer than that of many another scientific man whose life was 

 shorter than his by a quarter of a century. Even in Chevreul's seven- 

 tieth year it was very evident that he was already " a savant somewhat 

 past his faculties." 



During his declining years he had much to say, both by way of 

 reclamation and of explanation, in favor of the views and labors of ear- 

 lier investigators, and there can be no question that he held in mind 

 many matters of historic interest ; but, sad to say, in his enfeebled 

 condition the task of putting these things in order was beyond his 

 powers. Worst of all, perhaps, the ways of thinking of the new gen- 

 erations had become so unlike his ways that hardly any one could find 



