Responding in a high degree to the Emanations from Radium.
ZINC SULPHIDE SCREENS. CALCIUM SULPHIDE—Phosphorescent. ZINC SULPHIDE—Phosphorescent. PITCHBLENDE—Specimens.
_Write for particulars to_ JOHN J. GRIFFIN & SONS, Ltd., 20, 22, 24, 26, SARDINIA STREET, LONDON, W.C.
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