Experiment on all the preceding mixtures demonstrates the rule above; or rather, this rule is but the expression of a generalization of facts. RULE II.—THE MIXTURE OF COMPLEMENTARY COLOURS. 349. _When we mix Red with Green, Orange with Blue, Yellow with Violet, the colours are more or less completely neutralized, according as they are more or less perfectly complementary to each other, and as they are mixed in proper proportions. The result is a grey, the tone of which is generally higher than that of the colours mixed, if the latter are of a suitably high tone._ EXAMPLES.—_Red and Green._ Plate 12. 3 Red threads with 1 Green thread give a dull Red. 2 Red threads with 1 Green thread give a duller and a deeper Red. 1 Red thread with 1 Green thread give a Reddish-grey. The tone a little higher than the preceding. 3 Green threads with 1 Red thread give a Green Grey, the tone higher than the Green or the Red. 2 Green threads with 1 Red thread give a Grey, less Green, and of a higher tone than the two colours. In repeating the same mixtures with higher tones of the same scales of Green and Red, the tone of the mixture of 2 Green with 1 Red is higher relatively to that of the colours mixed, than it is in the mixtures above. 1 Red thread and 1 Yellowish-green thread give a Carmelite-brown or an Orange-grey, the tone of which is equal to that of the colours mixed. 1 Red thread and 1 Bluish-green thread give a copper-coloured mixture or catechu-brown of a higher tone than that of the colours mixed. Hence we may conclude that red and green threads, properly assorted, and in suitable proportions, yield _Grey_. _Orange and Blue._ 3 Orange threads with 1 Blue thread give a dull Orange. 2 Orange ” 1 ” ” a duller Orange. 1 Orange ” 1 ” ” Chocolate-grey. 3 Blue ” 1 Orange ” Violet-grey. 2 Blue ” 1 Orange ” Violet-grey. Redder than the preceding. [Illustration: PLATE XII.] The results are the same with deeper tones than the preceding, except that the corresponding mixtures are browner.