. Carnegie Institution of Washington publication. 54 INFRA-RED TRANSMISSION SPECTRA. GROUP IV: TRANSMISSION SPECTRA OF COLORED GLASSES. Cobalt Glass. (Fig. 37. Thickness, mm.) Colored glasses have been but little studied. Nichols1 examined cobalt glass, and found an absorption band at ;i. This is one of the few substances having a prominent band near the visible spectrum. Garnett (loc. cit.) concludes that the deep blue color of cobalt glass can not be due to small diffused spheres of metallic cobalt, which would give a reddish color to transmitted light, but that the metal is in the
. Carnegie Institution of Washington publication. 54 INFRA-RED TRANSMISSION SPECTRA. GROUP IV: TRANSMISSION SPECTRA OF COLORED GLASSES. Cobalt Glass. (Fig. 37. Thickness, mm.) Colored glasses have been but little studied. Nichols1 examined cobalt glass, and found an absorption band at ;i. This is one of the few substances having a prominent band near the visible spectrum. Garnett (loc. cit.) concludes that the deep blue color of cobalt glass can not be due to small diffused spheres of metallic cobalt, which would give a reddish color to transmitted light, but that the metal is in the form of discrete molecules (amorphous). For the present work a fluorite prism and bolometer were used (see Appendix II).. 2 3 Fig. 37. — Cobalt blue glass. In fig. 37 is given the transmission curve of a cobalt blue glass which showed three weak absorption bands in the visible spectrum. In the infra-red there is a larger absorption band at p., a smaller band at fi, and second large band at p. The small band at 3 /i is due to the glass itself, and is also found in quartz. Beyond 4 p. the opacity is due to the glass, as found in clear specimens. The behavior of this glass is entirely different from the red glasses to be noticed on a following page. It is not like an optically turbid medium, unless we consider it to have more than one region of selective absorption, which is in line with the conclusion arrived at by Garnett {loc. cit.). "Nichols, E. F.: Phys. Rev., 1, p. 1, 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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