. Carnegie Institution of Washington publication. WATICR OF" CRYSTALLIZATION. of H2O. It would have been highly desirable to procure more minerals which occur in the hydrous and anhydrous state, but none were obtain- able. The artificially dehydrated minerals, such as copper sulphate, were too opaque for examination after expelling all the water. The only exception is selenite, the various curves of which will now be considered. The anhydrite curve, b, is to be noticed first, from which it will be 90%. 01 234 56 FIG. 3.—Anhydrite (d) • Selenite. observed that there are small bands at 1.9,

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. Carnegie Institution of Washington publication. WATICR OF" CRYSTALLIZATION. of H2O. It would have been highly desirable to procure more minerals which occur in the hydrous and anhydrous state, but none were obtain- able. The artificially dehydrated minerals, such as copper sulphate, were too opaque for examination after expelling all the water. The only exception is selenite, the various curves of which will now be considered. The anhydrite curve, b, is to be noticed first, from which it will be 90%. 01 234 56 FIG. 3.—Anhydrite (d) • Selenite. observed that there are small bands at 1.9, 3.2, 5.7, 6.15, and 6.55 p., and an enormous band at 4.55 p, which will be shown later to be due to the SO4 ion. Turning to the selenite curve (a, fig. 2), it will be noticed that it is less transparent for the same thickness, 0.65 mm., and that in its general trend it is similar to the curve for water. All of its absorption bands coincide with water, with the exception of the 4.75 //, band, which is shifted to 4.6 /*. The shifting of this band is due to the SO4 band at 4.5 fi, as was found on examining anhydrite. The curve, c, for a thickness of 2.57 mm. is due to Konigsberger (loc. cit.).. 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 work.. Carnegie Institution of Washington. Washington, Carnegie Institution of Washington