ALBUMEN PROCESS (BEER) A dry collodion process for solar photography, introduced by Sir William Abney in 1874, also of use for landscape work. Abney's formula is : Alcohol (•825) . 41-3 drms. 270-180 ccs. Ether • • 3i-5 210-300 „ Pyroxyline7 grs. 7 g.
Ammonium iodide z „ 2 Cadmium bromide 5 „ 5 The relative proportions of alcohol and ether are adjusted according to temperature. The plate is then sensitised in a silver bath of from 40 to 6o grs. per oz., and is next washed, and the first preservative applied : Albumen . . . i oz. too ccs.
Water . . . r „ „ Liquor ammoniac . r drm. This is beaten to a froth and allowed to settle. The dear part is mixed with an equal quantity of flat beer or stout immediately before use, and is then applied to the plate ; fresh bottled beer or stout must not be used. The excess is then drained off, the film washed for two min utes, and finally covered with a solution made by adding to every ounce of plain beer 2 grs. of pyrogallic acid. The plate is then dried in the usual way. Great latitude in exposure is per missible, even up to twenty times the correct amount, and, if desired, the plates need not be developed for a month, but they need to be washed just previous to development. For developing, four solutions are necessary : A. Pyrogallic acid . 12 grs. 12 g.
Water . . . i oz. 50o ccs.
B. Liquor ammouiw (.88o) . . t drm. 62 ccs.
Water . . . i oz. 250C. Citric acid . . Go grs. 6o g.
Acetic acid . . 3o mins. 2 CCS.
Water . . . I oz. D. Silver nitrate . 20 grs. 20 g.
Water, distilled . i oz. 500 CCs.
Three drops of B are mixed with each hall-ounce of A, and flowed over the plate. The image will then gradually appear. Two more drops of B per half-ounce are added, the solution again flowed over the plate and returned to the meas ure. Six drops of C are placed in a measure, and the partially used developer poured on to it, afterwards adding a few drops of D. The appli cation of this solution intensifies the image. Abney states that it is not advisable to bring out too much detail with the pyro-ammonia solution, but to allow some of it to be brought up at the finish with the intensifier. When the image is sufficiently dense, the plate is fixed either by a solution of potassium cyanide or with "hypo," then washed and dried. The pro cess is not an easy one, and many failures are likely to be met with, but the resultant negatives, when all goes well, are of a remarkably high quality.