The American annual of photography (1919) (14782114742)

Identifier: americanannualof3334newy (find matches)
Title: The American annual of photography
Year: 1919 (1910s)
Authors:
Subjects: Photography
Publisher: New York : Tennant and Ward
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University



Text Appearing Before Image:
de 3.5 Sodium Sulphite (desiccated) A Sodium Carbonate (desiccated) B Water to 1000 cc. Effect of Varying the Sulphite Content While B was maintained constant and equal to 100 grams,A was varied as follows: (A) Time for Fog on Cine Positive at 80° F. 25 grams 3 mins. 50 3/2 75 5 100 6 125 7 150 6 Any increase in the sulphite content beyond 100 grams con-siderably retarded the rate of development, and as a minimumof fog was produced at this point, 100 grams was considered tobe the most suitable proportion.Effect of Varying the Carbonate Content A was maintained constant, equal to 100 grams, and Bvaried as follows: (B) Time for Fog on Cine Positive at 80° F.25 grams 3 mins. 50 3/2 75 4J4 100 S 125 5 ISO 4^ The least fog is therefore produced when the content ofboth carbonate and sulphite is equal to 100 grams. The most suitable formula is therefore: Elon 0.5 grams Hydroquinone 10 Potassium Bromide 3.5 Sodium Sulphite (desiccated) 100 Sodium Carbonate (desiccated) 100 Water to 1000 cc.
Text Appearing After Image:
wo Q w 29 The effect of dilution of this formula was to increase fog asfollows: To lOO volumes of the, developer C volumes ofwater were added. (C) Time for F6g on Cine Positive at 80° F.o vols 5 mins. 50 3 100 2 150 2y2 200 3 In practice on the large scale, the above developer was foundto give positives remarkably free from fog even after continualuse with the temperature of the developer and surrounding at-mosphere at 80° F. It was found that if the developer was splashed on the floorduring working, this crystallized out and caused trouble due toparticles of sulphite and carbonate dust settled on the film.This was overcome by replacing the sodium carbonate by anequal weight of desiccated potassium carbonate, since owing tothe dehquescent nature of the latter, any liquid splashedaround did not dry up but remained moist. The developer con-taining potassium carbonate was also somewhat more ener-getic than the one containing sodium carbonate. The increase of the fogging action on dilut