We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
44 Transactions ofS.M.P.E., Nov. 1924
by aerial oxidation of the developer during examination of the film add one part in 500,000 of Pinakryptol Green which will entirely eliminate aerial oxidation fog.
The following developer formula gives results very free from fog with a minimum of swelling. It is especially suitable for use with negative film.
Metric Avoir. P-aminophenol (Kodelon) 7 grams 3 lbs.
Sodium sulphite (desiccated) 50 grams 21 lbs.
Sodium carbonate (desiccated) 50 grams 21 lbs.
Water to make 1 liter 50 gal.
The Hardening Bath. After development rinse the film for not more than two to three seconds in water and immerse for at least three minutes in the following hardening solution.
Metric Avoir. Potassium chrome alum 30 grams 12 lbs.
Water to make 1 liter 50 gal.
Agitate the film for 30 to 45 seconds when first immersing in the hardener. This will tend to prevent any possible blisters, streakiness, or chrome alum stains. If the film is not rinsed slightly and agitated as above, the alkali in the developer is apt to precipitate a sludge of chromium hydroxide on the film, especially with a partially exhausted hardening bath, which is difiicult to remove. Blisters may tend to form if the film is swollen on immersing in the hardening bath as a result of decomposition of the carbonate in the developer b}^ the chrome alum which is normally acid, but agitation will tend to prevent the formation of such blisters.
The hardening properties of the above bath depend on
A. The aciditv of the bath
B. The alkalinity of the film
C. The age of the bath and quantity of developer carried over to it by the film
D. The time of immersion of the film in the bath
A plain chrome alum solution is sufficient^ acid to neutralize a considerable quantity of alkali carried over from the developer but the film should be rinsed in order to prevent the bath from rapidly becoming alkaline. The addition of acid to the bath is not recommended because this tends to produce bhsters. It is necessar^^, however, that the film should contain a certain quantity of alkali on immersing in the hardening bath in order to secure m.aximum hardening. As developer is carried over the color of the bath changes slowly from violet-blue by artificial light when freshly mixed to a yellow-green, in which condition it ceases to harden and should be replaced with a fresh bath. A fresh bath will remain violet colored and retain its hardening properties indefinitely, but once a small quantity of developer is added certain chemical reactions occur which gradually destroy the hardening properties depending upon the