Page:Handbook of Precious Stones.djvu/13

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to say, present any obvious differences from the corresponding figures in the plate issued in 1882 with the first edition of this handbook. But they do show a marked superiority over the spectra figured in subsequent issues. The nine upper figures in the Frontispiece show the twin colours of certain precious stones, figs. 1 to 6 representing the hues as seen in the dichroiscope.


Kew Gardens, February, 1905.