Without doubt the best results are obtained from the use of a plain neutral solution, kept as near as possible to its full strength, varying from 45 to 60 gr. of silver nitrate per oz. of water, kept as near neutral as possible by means of soda carbonate, and floating 3-5 minutes.
To prepare a sensitive paper that keeps white for a week or so, nothing has been published that works so well as Mr. Blanchard's formula, as follows: - Prepare the silver solution, 60 gr. to the oz., and be careful not to allow it to sink lower than 50 gr. to the oz.; for each oz. of nitrate used, add 10 drops of a saturated solution of citric acid; now add nitric acid drop by drop, until the slight precipitate of silver citrate formed is just redissolved. Float for 3-5 minutes, and upon taking from the bath, place between sheets of clean blotting-paper, which may be used over and over again until their power of absorption is almost destroyed, it being needless to observe that when this stage is reached, the blotting-paper is especially available for the silver waste basket. Paper so prepared has been kept white and good for 9 months, and the results, in the way of the fine, rich, vigorous prints, and ease of toning, leave nothing to be desired.