Natural philosophy. Ideal Colours.

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Perhaps the most interesting part of M. Hundertpfund's work, just quoted, is the chapter on Ideal Colours (Idealn Farben); because it discloses the principles on which the system in question is built.

The author sets out with a definition of light and darkness as they relate to colour. But his definition is not in harmony with that commonly accepted. Light is generally supposed to be a substance, and darkness to be the mere absence of light. But M. Hundertpfund treats them both as substances each a sort of sympathetic affection for each other, and as having, each of them, a disposition to attract and expand. "When light," he says, "yields itself up to darkness, the darkness receives and draws it into its own body, and becomes softened by it. The light, however, suffers by the incorporation. On its first entrance into darkness it loses its primitive splendour, and exhibits itself as a blue transparent object. As it enters more deeply into darkness its blue bcomes more and more tinged with red, until a point is reached where darkness has completely absorbed the light, and then a perfect red appears, softening the austerity of the gloom, and exhibiting itself in great splendour."

This, according to the author's hypothesis, is the natural cause of the blue and red and their derivative purple. The cause of the yellow he attributes to a disposition on the part of the light to release itself from the darkness after being absorbed by it. On reappearing, influenced by darkness, it assumes a yellow colour, tinged at first with red, and then less and less so till the yellow stands alone. The intermediate colour is of course orange: — i. e. the derivative of red and yellow.

The other derivative, green, is supposed to be formed in consequence of a disposition on the part of the yellow, or rather of the light, to direct itself towards the point where it first entered the darkness, and so to come into contact with the blue: which seems to presume that there is in light a propensity to take a circular course through darkness, and to return to the point at which it set out.

We know but little about light; the nature of which, like that of many other things, has as yet been more the subject of conjecture than of demonstration. M. Hundertpfund's ideas must therefore stand or fall according to their intrinsic justice but there are many things which seem to confirm them. For instance, let any one light a candle in a dark room, and watch the progress of its ignition. He will observe (particularly if the candle lights slowly) that its first flame is blue, that it then becomes red, and at length blazes up from an orange into a bright yellow. This course of transition is in harmony with M. Hundertpfund's hypothesis; for it will be the natural result of the following causes: — light is produced, and as it enters into the darkness (which is at first stronger than the light) it becomes blue; then, as it is further affected, violet and red: and when at last it frees itself from the darkness and triumphs over it, orange and yellow. It may be remarked, also, that in daylight, in the open air or in a room lighted up strongly by sunshine, this transition of colours is not perceived, and that in proportion as the room is in shade will the transition be more and more strongly visible.

Letter, in the Athenæum, No. 1084.

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