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.
154 CINEMATOGRAPHIC ANNUAL »
Sodium aluminum silicate + calcium sulfate = sodium sulfate -\ calcium aluminum silicate.
(Zeolite)
When the zeolite thus loaded with calcium and magnesium is washed in a strong solution of common salt (about 12%) it exchanges its calcium and magnesium again for sodium and is thus regenerated, whereupon the chemical may then be used for further softening.
Calcium aluminum silicate -\ sodium chloride = sodium aluminum silicate + calcium chloride.
(Zeolite)
The Use of Sea Water
Sea water contains a relatively large proportion of soluble salts (about 3 J/2 %) and should not be used for mixing photographic solutions except in extreme emergencies when no other water is available. This is because the dissolved salts such as chlorides, and iodides may retard the action of the photographic solution. When the supply of fresh water available is very small, sea water may be used for washing motion picture film, providing a last washing or soaking previous to drying is given in distilled or fresh water.10 The film should be given a thorough washing later when plenty of fresh water is available.
A chemical analysis of the water supply usually reveals very little concerning its photographic usefulness. It may be of some assistance in indicating the quantity of lime, oxalate, etc., to be added to remove dissolved calcium salts or to coagulate slimes. The quantity of total solids indicates if trouble from drying marks may be anticipated, while the presence of iron, hydrogen sulfide or metallic sulfides should be regarded with suspicion. The only useful test is to prepare a developer with the sample and actually try it out compared with the same developer prepared with distilled water.
Also, a large drop of water should be allowed to dry on the film and the amount of residual scum observed. This will indicate the extent of the trouble to be expected if the water is not removed thoroughly before drying.
Practical Recommendations
If developing solutions are mixed with warm water (about 125° F.) and allowed to stand over night, any precipitate or suspended matter will settle out and the clear supernatant liquid may be drawn off for use. The presence of calcium and other salts in the water supply is sometimes beneficial insofar as they tend to retard the swelling of the gelatin coating of the film during washing. This is of particular advantage in hot weather.
The only impurities liable to cause serious trouble with developers are hydrogen sulfide or soluble metallic sulfides. With such water