A Treatise on Photography (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1881 Excerpt: ...strengths of solution should be: --Silver nitrate.... 6 grammes Water 100 cc. and Silver nitrate....15 grammes Water 100 cc. The paper is floated on either of these solutions in the manner given for albumenising paper, the time of contact varying from three minutes in hot to five minutes in cold weather. It should be removed slowly from the sensitising bath to prevent waste of solution, and when hung up to dry by an American clip in the dark room, the drainings should be collected by attaching a slip of blotting-paper to the bottom corner. It is always advisable to have one corner lower than the others, as the sensitising solution thus drains more equally away. In order to preserve sensitised paper from colouration due to the decomposition of the organic salt of silver, it may be placed between sheets of blotting-paper impregnated with sodium carbonate. Other devices have been adopted for the same purpose; descriptions of them will be found in the various manuals. Printing the Picture. Printing operations are rarely carried on in the same temperature and state of atmospheric moisture as those in which the paper is dried; hence it is advisable to allow the paper to assume the conditions of the former before rigidly confining in the frame. The fact that paper expands in moist air at once shows that the dimensions of a photograph can never be relied upon as being accurate. Measurements have shown that a drawing, for instance, will vary as much as 1 per The Printing Frame. 147 cent. in certain conditions of the atmosphere. The same remark applies to plans printed in the ordinary lithographic press; the scale is never correct except under fixed conditions. The negative should be placed in the printing frame with the varnished side next the paper. A convenient for..