Studies of iridescent colour, and the structure producing it.—II. Mother-of-pearl

Abstract

The colours of mother-of-pearl were studied by Brewster and he recognised that the colours were to be classed under two heads—what he called transferable and non-transferable colours. The former could be transferred to gelatine or other soft substances, employed to take a cast of the mother-of-pearl surface, and in this way it was clearly shown that the colour was due to diffraction by grooves on the surface. The non-transferable colours on the other hand were classified with the colours of thin plates, due to the stratified structure of the shell. The grooved surface was naturally explicable as resulting from the out-crop of these strata.