Proceedings of the United States National Museum . Fig. 17.— side view ofcrystal a g g r e-gate similar tothat shown in FIGURE 16. barely perceptibly. The main portion of the crystal shows inter-ference colors mostly in subnormal blue and liver brown with avery little first-order yellow. All portions of the pattern yielda similar interference figure in convergent hght,biaxial positive, 2V approximately 10°, acute bisec-trix perpendicular to the table, axial plane parallelwith the long direction, r>v strong. These inter-ference figures are somewhat hazy and is most pr
Proceedings of the United States National Museum . Fig. 17.— side view ofcrystal a g g r e-gate similar tothat shown in FIGURE 16. barely perceptibly. The main portion of the crystal shows inter-ference colors mostly in subnormal blue and liver brown with avery little first-order yellow. All portions of the pattern yielda similar interference figure in convergent hght,biaxial positive, 2V approximately 10°, acute bisec-trix perpendicular to the table, axial plane parallelwith the long direction, r>v strong. These inter-ference figures are somewhat hazy and is most probably like the preceding, but theportions of scales making up the hourglass are soexceedingly thin that they do not greatly obscurethe optical properties of the main crystal, eventhough the latter is itself very thin. The explanation implying an overgrowth of scalesisnotpurely hypothetical, especially since any of the crystals when care-fully examined un-der a lens do showsuch scales, indeed usually a groupof them, curving upward. This issimi
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Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
