The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Toning
addition of alkaline gold to the fixing bath was recommended, and the author has proved this to be of great value to prevent loss of tone, sel d'or being actually formed. The following is the formula referred to : -
Chloride of gold ............ i gr.
Carbonate of soda ... ... ... ...    20 grs.
Hypo...... ...... ... ... 4 ozs.
Water          ...............    20 ..
Add the gold and soda mixed together to the hypo solution, stirring constantly. Mr. Anthony, of New York, recommends making the fixing bath distinctly acid both to test paper and sight by a slight turbidity, by the addition of acetic acid, and then neutralising the free acid by the addition of carbonate of soda or liquor ammonia till distinctly alkaline to test paper. This the author has tried and found useful; but in every case the fixing bath should be distinctly alkaline, either by carbonate of soda or ammonia.
Yellowness of the Whites of Prints. This is at once a sure sign of the acidity of the fixing bath, and consequent sulphur toning. Nothing can be done but to immediately destroy the print, and make the fixing bath alkaline. It more generally makes its appearance in cases of over-toning, when some secondary action seems to take place.
Black Deposit in Toning Baths. On keeping for some time, especially when extreme cleanliness and exclusion of actinic light has not been attended to, all toning baths deposit, more or less, a purplish black precipitate, which is metallic gold in an extremely fine state of division ; and when this deposit has occurred the bath is utterly useless. To renovate these old baths the following plan may be adopted : - Collect the preci-pitate, wash it well, and shake up with distilled water acidulated with nitric acid (1 to 80); add to this a solution of chloride of lime, made by mixing 80 grs. of chloride of lime with 1 oz. of water, and filtering; add the last solution gradually to the deposit of gold mixed with water, and heat to the boiling point; it will then be found that as more chloride of lime solution is added the gold will dissolve. When entirely dissolved, it may be kept for future use, and sufficient chalk added each time to neutralise any free acid before using. Another method of
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