Note 295 — APPENDIX. (continued 2)

“Whether a carbuncle (which is esteemed the best and biggest of rubies) doth flame in the dark,” says Sir Thos. Browne, in his Enquiries into Vulgar and Common Errors, B. ii, ch. v, “or shine like a coal in the night, though generally agreed on by common believers, is very much questioned by many.” On this Wilkin, the editor of Browne’s works, 1835, vol. ii, p. 354, remarks: “That which Sir Thomas much doubted has since been subjected to the test of repeated observations and many curious experiments, by which the phosphorescence of the diamond, sapphire, ruby, and topaz, as well as of many minerals and metals, and various other bodies, is fully established. Mr. Wedgewood has treated the subject fully in the 82nd vol. of the Philosophical Transactions. This luminous property, which seems to be strictly phosphoric, is made apparent by subjecting the body in question to heat in various ways. Several fluids (oils, spermaceti, butter, etc.) are luminous at or below the boiling point: minerals and other bodies become so by being sprinkled on a thick plate of iron, heated just below visible redness. The gems and several of the harder minerals emit their light upon attrition.”