. Carnegie Institution of Washington publication. 46 INFRA-RED TRANSMISSION SPECTRA. Fluokite (CaF). (Curve c, / = mm.; curve d, t = io mm.; curve e, / = mm.; curve/, /=3-85 mm. light-green color; fig. 29.) On account of the increased scarcity of this material, it is of interest to determine the effect of inclusions upon the transmission. In fig. 29, curve c was a perfectly clear specimen; while curve e contained numerous small inclusions, or, perhaps more exactly, small cleavage planes. The latter when held at a distance of 30 to 50 cm. from the eye appeared quite blurred. Neverthel
. Carnegie Institution of Washington publication. 46 INFRA-RED TRANSMISSION SPECTRA. Fluokite (CaF). (Curve c, / = mm.; curve d, t = io mm.; curve e, / = mm.; curve/, /=3-85 mm. light-green color; fig. 29.) On account of the increased scarcity of this material, it is of interest to determine the effect of inclusions upon the transmission. In fig. 29, curve c was a perfectly clear specimen; while curve e contained numerous small inclusions, or, perhaps more exactly, small cleavage planes. The latter when held at a distance of 30 to 50 cm. from the eye appeared quite blurred. Nevertheless, throughout the infra-red the loss of energy is only about 2 per cent greater than that of clear fluorite. This is to be expected; for each cleavage plane reflects some of the light, and the magnitude of this reflection, since it depends upon the refractive index, decreases with increase in wave-length. Curve / shows the transmission of a specimen of light yellowish-green fluorite (see Carnegie Publication, No. 65, p. 69, for another example) which has an absorption band at /<, hence not suitable for a prism. This specimen was free from inclusions. Carbon (C). (Curves a, b, c, lampblack; curve d, diamond; fig. 30.) The commonest and most conspicuous example of the effect of structure upon absorption is to be found in carbon in the form of lampblack and 100% t=.009mm. 3 4 5 6 7 0 Fig. 30. — Carbon (a), (6), (c); Diamond. of diamond. Since the observations on these two substances are published in separate and rather isolated places they are incorporated here for com- pleteness of illustration of the effect of structure. The transmission curves. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Carnegie Institution of Washington. Washington, Carnegie Institution of Washington
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