Triumphs and wonders of the 19th century, a volume of original, historic and descriptive writings showing the many and marvellous achievements which distinguish an hundred years of material, intellectual, social and moral progress (1901)
Boyd, James Penny, 1836-1910 · Philadelphia, A. J. Holman & co · leaf 222
is that metallic salts, sensi-tive to the light, when in contact withorganic matter, suffer a complete orpartial reduction and are rendered in- LOUIS jacques dagueuue. soluble. The intensity of the reduc-tion is measured exactly by the intensity of the light. When light isreflected from any object… … 204 TRIUMPHS AND WONDERS OF THE XIXth CENTURY reflection. Thus, when the unreduced metallic salt is washed out, a perma-nent record, the negative, of the object is left. It is a long step from the first daguerreotype to the modern photograph,but the principle of the process has remained unchanged.…
Progress · Inventions
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