Meddelelser om Grønland . ng table: ?: the a and è-axis brownish vellow I?: the c-axis greenish. This distribution of the colours is rather extraordinary, asit almost corresponds with the different colours obtained bytransmitted light, which are to be mentioned hereafter; before-hand we should rather expect that the colours most absorbed 85 by the transmission, would also be reflected to the highestdegree. By the way of examination mentioned above, the differentcolours are still only seen as rather faint tints of the pre-dominant black colour; if we wish to see them especially markedoff alongs
Meddelelser om Grønland . ng table: ?: the a and è-axis brownish vellow I?: the c-axis greenish. This distribution of the colours is rather extraordinary, asit almost corresponds with the different colours obtained bytransmitted light, which are to be mentioned hereafter; before-hand we should rather expect that the colours most absorbed 85 by the transmission, would also be reflected to the highestdegree. By the way of examination mentioned above, the differentcolours are still only seen as rather faint tints of the pre-dominant black colour; if we wish to see them especially markedoff alongside of each other, we shall have to use convergentlight and Nicol prisms, placed crosswise; the polarizer mustthen be placed in a horizontal position in a stand before theprism of the objective. The convergent light is produced byusing a strong objective. We shall then, when the light isreflected from a bright plane, generally see a picture as theannexed figure, that is, a semicircle with a bisected blackcross. P A —. Fig. 32. PP and ?? indicate respectively the directions of oscilla-tion of the polarizer and the analyzer. The rays reflected nearthese lines, will after the reflection keep the direction of oscil-lation PP, and so they are completely absorbed by the analyzer. 86 It is otherwise with the interjacent parties. A ray, for instance,impinging on ilf, falls obliquely down on the reflecting plane,and the direction of oscillation PP forms an angle of 45° withthe plane of incidence. By the reflection the ray is dividedinto two components, one of which oscillates in the plane ofincidence, the other at a right angle to this plane; the greaterpart of the former is absorbed, while the latter is almost entirelyreflected. After the reflection the two components, which get,moreover, a greater or smaller difference of phase dependenton the angle of incidence, are joined into an elliptically polarizedray, which closely approaches to being rectilinearly polarized,if the ray is
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