We may notice that ethyl oxalosuccinonitrile is the first case of a fluorescent aliphatic compound.
Clear amber is found beside the Buzeu and its affluents, with brown and grey clouded amber, and a blue fluorescent variety, of considerable value.
The acid solution of sulphate of quinine is fluorescent, especially when dilute; and it is laevo-rotatory.
The bark of the horse-chestnut contains a greenish oil, resin, a yellow body, a tannin, C26 H 24012, existing likewise in the seeds and various parts of the tree, and decomposable into phloroglucin and aesciglyoxalic acid, C 7 H 6 O 3, also aesculetin hydrate, and the crystalline fluorescent compound aesculin, of the formulaC21H24013 (Rochleder and Schwarz), with which occurs a similar substance fraxin, the paviin of Sir G.
The oxide is a black or brown powder according as it is prepared from the exalate or sulphate, and when pure it is non-fluorescent, but mixed with gadolinia or alumina it possesses this property.