"DRAPER, JOHN W. - THE ""TITHONIC RAYS"" AS THE FOURTH IMPONDERABLE AGENT.
Reference : 44759
(1843)
(London, 1843). No wrappers In: ""The London, Edinburgh and Dublin Philosophical Magazine and Journal of Science"", Third Series, September issue 1843. Pp. 161-240 (entire issue offered). Draperspaper: pp. 161-176.
The paper appeared the same year in ""Proceedings Am. Phil. Soc."" and it is an importent paper on the chemical action of light, the new science of photochemistry in which Draper made pioneering work, showing that it is only certain light rays of a definite wavelenght that is absorped, and it is this absorption that produces the photochemical effect.