Note 129 — Chapter VIII

The chemical evidence of this will be found in Sir John Herschel’s Memoir On the Solar Spectrum, and particularly as exemplified in the changes produced on the tartrate of silver. Similar influences are described as observed on a Daguerreotype plate, in a paper entitled Experiments and Observations on Light which has permeated coloured media, and on the Chemical Action of the Solar Spectrum; by Robert Hunt.—Philosophical Magazine, vol. xxvi. 1840.