ultramarine (U), and emerald-green (E). The accuracy of the results,
and their significance, can be best understood by referring to the
paper before mentioned. I shall denote mineral blue by B, and
chrome-yellow by Y; and B3 Y5 means a mixture of three parts blue and
five parts yellow.


Given Colour. Standard Colours. Coefficient
V. U. E. of brightness.

B8 , 100 = 2 36 7 ............ 45
B7 Y1, 100 = 1 18 17 ............ 37
B6 Y2, 100 = 4 11 34 ............ 49
B5 Y3, 100 = 9 5 40 ............ 54
B4 Y4, 100 = 15 1 40 ............ 56
B3 Y5, 100 = 22 - 2 44 ............ 64
B2 Y6, 100 = 35 -10 51 ............ 76
B1 Y7, 100 = 64 -19 64 ............ 109
Y8, 100 = 180 -27 124 ............ 277


The columns V, U, E give the proportions of the standard colours which
are equivalent to 100 of the given colour; and the sum of V, U, E
gives a coefficient, which gives a general idea of the brightness. It
will be seen that the first admixture of yellow _diminishes_ the
brightness of the blue. The negative values of U indicate that a
mixture of V, U, and E cannot be made equivalent to the given colour.
The experiments from which these results were taken had the negative
values transferred to the other side of the equation. They were all
made by means of the colour-top, and were verified by repetition at