Snelling, Henry Hunt, 1816-1897 · [New York : W.B. Smith] · leaf 194
t day, and a properlyprepared plate, in the open air, ought notto exceed ten or fifteen s< conds ; after theproper time has elapsed the frame shouldbe closed, the plate taken out of the came-ra, and submitted to the next operation,namely, bringing out the picture by thevapor of mercury, for if… … 65. Fig. 2 represents an apparatusfor this purpose. The box is made ofwood of the form represented in the figure.The bottom is of iron, slightly dished inthe centre ; this is for containing a smallquantity of mercuiy, the bulb of a thermo-meter indicates the temperature obtained.The plates are…
Photography · Art and photography
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