. Carnegie Institution of Washington publication. 56 INFRA-RED TRANSMISSION SPECTRA. red; it was taken from a Le Chatelier pyrometer and is described as a copper oxide glass. Although thinner, the second sample is the more opaque in the region of i to ,u. The transmissivity of the monochro- matic red glass is very unusual. In the region of 1 to p. the metal which is used to color the glass renders it more permeable to heat waves than is ordinary, visually transparent glass. The band at p appears to be intensified by the presence of the metal, which behaves like the 100% 90% 80 70 6
. Carnegie Institution of Washington publication. 56 INFRA-RED TRANSMISSION SPECTRA. red; it was taken from a Le Chatelier pyrometer and is described as a copper oxide glass. Although thinner, the second sample is the more opaque in the region of i to ,u. The transmissivity of the monochro- matic red glass is very unusual. In the region of 1 to p. the metal which is used to color the glass renders it more permeable to heat waves than is ordinary, visually transparent glass. The band at p appears to be intensified by the presence of the metal, which behaves like the 100% 90% 80 70 60 c 0 ' (0 50 'I (0 1- t- 30 20 10 /'I / 1 1 1 I l\ 1 j 1 l\ 1 1 J *M. Fig. 39. — Green glass. 12 3 4- Fig. 40. — Ruby glass (a) and (6); Sphalerite. colloidal suspensions just mentioned. In fact, it is a pertinent question whether the red color in glasses is due to the presence of metals, such as copper and gold, in the colloidal condition. The monochromatic red glass was found to have a uniform reflecting power (about 4 to 5 per cent) throughout the spectrum to 8 [x. This seems to show that the transparent region at 1 to 2 ti is not due to the same cause that produces an abnormal transparency on the short wave-length side of a region of anomalous dis- persion. Black Glass. (Fig. 41. Curve a, £ = mm.; curve b, Schott's Rauchglass No. 444, III, t—s-6 mm.) Curve a gives the transmission of a dark "neutral" glass, colored with the oxides of cobalt and nickel. This glass has a uniform absorption throughout the visible spectrum. There are small absorption bands at 2 and p., respectively. Curve b gives the transmission of a very dark glass, which shows an absorption band in the region of ,«. Considered as a whole, these glasses can be divided into two groups,. 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 res
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