Pringle, Andrew · New York : Scovill & Adams Company of New York · leaf 35
e sun for some days, filter very carefully and re-acidify with nitric acid. The bath must, of course, be kept up to strength, to test which a hydro- meter arranged as an u argentometer ” may be used. When one bath is undergoing any of these regenerating processes, the duplicate previously… … Fig. 3. exposure in the camera must be found out by experiment, but copying a negative of average density, reducing to one-third size, lens at daylight in autumn, fine ground glass behind negative, system pointing toward sky, chemicals in good order, bath fairly acid, we find an exposure of about…
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