Scientific Memoirs; Being Experimental Contributions to a Knowledge of Radiant Energy Volume 50,

Scientific Memoirs; Being Experimental Contributions to a Knowledge of Radiant Energy Volume 50,

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1878 edition. Excerpt: ...attained; that, passing on to the sixteenth, no increase of whitening is to be perceived, although the quantities of light that have been incident and absorbed have been continually increasing; but as soon as the light thus latent has reached a certain quantity, visible decomposition sets in, indicated by a blueness, and the sensitive surface once more renders evident the increments of incident light. Or, by presenting a plate covered with a screen to a sky that is clear or uniformly obscured, and with a regular motion withdrawing the screen deliberately from one end to the other, and then suddenly screening the Whole, it is plain that those parts first uncovered will have received the greatest quantity of light, and the others less and less. On mercurializing, it will be seen that a stain will be evolved on the plate, as is represented in Fig. 37; from a to b the changes have been successive; from b to c no variation in the amount ofwhitening is perceptible; at d solarization is commencing, which becomes deeper and deeper to the end, e, of the stain. Fig. 37. "' It is impossible to represent these changes in a drawing which is simply black and white; it will be understood that the characteristic distinction of the spaces from the sixteenth to the twentieth, for example, depends on their assuming a blue tint, which continually deepens in intensity. The plate from which the drawing of Fig. 37 is taken gives from a to b ten parts, from b to c seventeen parts, from d to e twelve parts; we perceive, therefore, how large an amount of light is absorbed, and its effects rendered latent, between the maximum of whiteness being gained and solarization setting in. 4th. That it depends on the CHEMICAL nature of the ponde-rable material...show more

Product details

  • Paperback | 130 pages
  • 189 x 246 x 7mm | 245g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236776267
  • 9781236776266