The silver sunbeam : a practical and theoretical text-book on sun drawing and photographic printing (1873)
Towler, John, 1811-1889 · New York : E. & H.T. Anthony · leaf 576
538 DEVELOPING. An excellent developer for ferrotypes is made as follows : Prepare a saturated solution of protosulphate of iron, also dissolve two grains of tannin in an ounce of alcohol. Add gradually of the tannin solution to that of iron until the lat- ter ceases to redissolve the precipitate… … vety blacks and rich, pure whites. The ordinary developer for ferrotypes can be very much improved by merely adding a trace of tannin to it just before being used. A defect, frequently occurring in ferrotypes, viz., a yellow color after being varnished, can be prevented by proceeding as follows :…
Photography
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
