photographs by artificial light, 228.
photographs in natural colours, 228.
Pollock's process, 17.
positives, 15. 17. 397. 451.
precision in photographic processes, 301.
protonitrate of iron, 228.
printing on albumenised paper, 324.
Pumphrey's process for black tints, 349.
restoration of old collodion, 650.
Sisson's developing solution, 157. 181. 253. 301. 373.