Atmosphere : a philosophical work / by George Woodhead.

  • Woodhead, George.
Date:
1852
Catalogue details

Licence: Public Domain Mark

Credit: Atmosphere : a philosophical work / by George Woodhead. Source: Wellcome Collection.

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    those apparatus and their effects con- tribute to the truth of these views. But how the impressions so made on the oro-ans of vision are communicated to the mind, I do not here intend to inquire, mv present purpose being to deal only with matter and material things. Light, therefore, is matter in a state of directly radiating or reflected, on paper or other sub- stances charged with, a chemical preparation extremely sensitive of the effects of light. Different methods are used. Of one proposed by Mr. Talbot, the general arrangements are stated by Dr. Reid, in his Elements of Chemistry, to be as follows : — Take paper, and steep it in a dilute solution of salt, dry it, and steep it again in a dilute solution of nitrate of silver so as to impregnate the paper with chloride of silver, which is formed upon it by the mutual action of the common salt and nitrate of silver. By repeating this in diluted solutions with much care, excluding the light as the paper is dried, a surface is at last obtained fit for use. When a drawing is to be made with this paper, an outline, or engraving, or a leaf, a flower, or any similar object, is properly arranged on one side of a thin glass plate and the prepared paper on the other, and on exposing the first to a brilliant light, the prepared
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