HYPO IN DEVELOPERS.

New Zealand Mail, Issue 1267, 11 June 1896, Page 13

HYPO IN DEVELOPERS.

Dr It. Noahaus describes bis experience with “Hypo in Amidol developer” in tho Photo'jraphische Rundschau,. Tho Amidol developer was the following;— Amidol 2 gr Sodium sulphite ... 20 gr Water 100 c.c. For uso, 1 part of tho above is diluted with 3 parts of water, and a few drops of a 1 in 10 solution of potassium bromide are added. A systematic series of experiments was carried out. In each instance the plate used was e«t--in half; one half was developed in 40 c.c. of tho above Amidol solution, the other half was developed in a similar quantity to which, however; b£-a 10 per cent, solution of 5 nypo r 'wero added. One to 3 drops of tho hypo solution causeda marked acceleration in the action of tho developer. Up to the 12 drops ti?e result was tho same, but <lif3_imago „was rather pluckier than when the hypo was omitted. Beyond this amount the hypo began to exert a restraining action ; with 48 drops this was pronounced, and very much so with 3 1 c.c. per 4-0 c.c. of developer. The image, too, was now less plucky than with the plain Ami(l oj dcf'elqper. The •negatives showed no moro tendency to fog than when the hypo was omitted; in fact, less when 3 or 4 c.c. woro used. An acid hypo solution behaved in tho same way. The addition of tho hypo solution to the developer, before or after tho plato had been immersed, seemed to make no difference.