XI. On the production of coloured spectra by light

Abstract

Last year I incidentally mentioned in a note to the Royal Society (“Proceedings,” vol. xxviii, p. 291), that the production of natural colours by the agency of light, examples of which were shown by Becquerel, was probably caused by the oxidation of silver compounds employed. I have ventured to return to the subject, in order to show that the colours are so produced and are not due to interference. I have sent, for the Society’s inspection, pictures of the solar spectrum on silver plates, and also on compounds of silver held in situ by collodion. It will be observed that the spectrum has imprinted itself in approximately its natural colours; that on the silver plates it is more brilliant than on the collodion film, but that in the latter the colours are seen by transmitted as well as by reflected light.