A Primer of Art

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1882 edition. ...mixtures of coloured lights--by scarlet and bluish-green, by greenish-yellow and violet, by yellow and ultramarine, by red, green and violet, or finally by a mixture of all the colours of the rainbow. All these mixtures produce precisely the same impression on the eye, but in no other respect are they alike. For instance, a surface lighted up by scarlet and bluish-green light will come out black in a photograph, whereas another lighted up by greenishyellow and ultramarine will come out very light. To the eye they would both look equally white. In fact there is no resemblance between the physical properties of these various mixtures of light. They agree in producing the sensation of white, but in nothing else. According to Young's theory the explanation of the puzzle is a very simple one. These various mixtures are alike in this--that they all excite all three of the nerve elements. For instance, in the first mixture the scarlet excites the red-seeing nerves, whilst the blue-green light excites the other two sets. In the second mixture the greenish-yellow excites the red and green-seeing nerves, whilst, of course, the violet light excites the violet-seeing ones. And so on throughout the series. It may startle those who are only accustomed to the mixture of pigments to hear that blue and yellow light do not produce green but white. That this is so can be readily proved by the experiment mentioned above. But why do blue and yellow paint produce green? It is a question, as we have mentioned before, of the subtraction of colours, not of their addition. The blue paint absorbs most of the red, orange and yellow waves, reflecting back to the eye the green, blue and violet, the result of which is a general impression of blue. Now take a yellow...