24 de Novembro
ABSTRACTS OF THE PAPERS,
PRINTED IN THE PHILOSOPHICAL TRANSACTIONS
ROYAL SOCIETY OF LONDON
Pag. 398, 399
Proceedings of the royal society
1. “ On certain improvements on Photographic Processes described in a former communications”. By Sir John Frederick William Herschel, Bert, K. H., F. R. S., &c., in a letter to Samuel Hunter Christie, Esq., Sec. R. . Communicated by Mr. Christie.
The present memoir, which is a sequel to the last by the same author, is accompanied by a series of photographic impressions illustrative of the chrysotype, cyanotype, and other processes formely described by him. Some improvements which he has introduced into these processes are given, together with a few remarks on some other points treated of in the former paper, in relation to the inflaence of thermic rays as distinct from calorific rays; the former being rays, which in the spectrum accompany the red and orange rays, which also copiously emitted by heated bodies short of redness, and which are distinguished from those of light by being invisible. The author thinks they may be regarded as bearing the same relation to the calorific spectrum which the photographic rays do to the luminous one, and would propose to designate them by the term parathermic rays. He conceives that these may be the rays which are active in producing those singular molecular affections determing the precipitation of vapours in the experiments of Messrs. Draper, Moser, and Hunt, and which will probably lead to important discoveries as to the intimate nature of those forces, resident on the surfaces of bodies, to which M. Dutrochet has given the name of cpipolic forces.