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SEPTEMBER 7, 1883.] THE PHOOGRAPHIC NEWS 565 to produce a veil over the distance, causing it to become blended with the sky-line. 2. With sulphite developer, green or red fog is almost certain to occur in presence of chlorides. Chloride causes a general weakness in the image. 3. With oxalate developer, unless chloride is largely present, fog is not necessarily caused. Increase of chloride causes a marked weakness in the image. There is not any apparent difference in the colour of the image in the presence of chloride, as there was in the case of iodide. On the whole, it is difficult to seo where the advantage of using chloride exists. In all the above cases, the results were far inferior to those obtained by pure bromide. The oxalate developer gave the best results. Probably, many who imagine the presence of chloride in their films, do not really get it at all, as silver chloride, when boiled with excess of potassium bromide, passes into silver bromide. Possibly this may account for some of the differ ence of opinion respecting the use of chloride. If used at all, it must evidently be in very small quantity; there is no Comparative View of the Effect of Variation in the Eclative Proportions of Iodide and Chloride in Emulsions. Number of Plate and nature of Emulsion. Ordinary Pyro Developer. Sulphite Developer. Oxalate Developer. Plate 1— Portion coated with AgBr ... Ditto, AgBr 4- 2-50/AgI + 2'o»/ o AgCl Ditto, AgBr+5°/ 0 AgI-}- 2-5%AgCl Green fog in shadows; a little thin; otherwise good. No green fog; a trifle more density than above. Green fog in shadows; not so good as above. Sky chocolate brown by reflected light in 2nd and 3rd portions. Not good ; shadows veiled; green fog. Increased green fog. Still more green fog. Whole negative bad, but 2nd and 3rd portions much worst. Much quicker in developing. ) Thin, under-developed, and f foggy; image browner by ) reflected light. The three portions clearly dis tinguishable. Plate 2— Portion coated with AgBr ... Ditto, AgBr-70/AgI- 8/gl Ditto, AgBr-+120/Ag1+ 3°/0gCl Green fog; thin ; lacks detail. Only trifling green fog on shad ows; vigorous; good. Foggy, and generally had. 2nd divisions prominently the best. Good density; fair negative. Not so dense as above; slight green fog. Slight decrease in density; slight green fog. Good density; no fog; shadows clear. ) Less density; each portion > clearly seen by decrease in ) density. Plate 3— Portion coated with AgBr ... Ditto, AgBr-2-50/AgI- &7oAgCl Ditto, AgBr+3 o /oAgI-|- 7%/0AgCl Less density ; greater clearness of shadows and distance; very slight green fog. ) More green fog; greater den- - sity, but less clearness of ) shadows and distance. Distinction not very prominent. Fair density; only slight green fog. ) More green fog than above; F shadows veiled; density J same as above. Distinction not very prominent. Good, bright, and vigorous; quicker in developing. f Very slow in developing; ( green fog ; shadows veiled. 1st portion prominently the best. Plate 4— Portion coated with AgBr ... Ditto, AgBr-30/AgI+ 12o/„AgCl Ditto, AgBr-+60/Ag1+ 15%AgCl Less density, but clearer shadows and distance; greater con trast ; only slight green fog. Denser; more green fog; dis tance less clear. Denser; more green fog; shad ows and distance veiled. No discernible difference; same density throughout, and slight green fog everywhere. Good density; bright and vigor ous ; no fog. ) Thin and foggy, as if much ) over-exposed. Plate 5— Portion coated with AgBr- 3»/ 0 AgI+7»/ 0 AgCl Ditto, AgBr4-7%AgI-{- 3°/gl Shadows veiled; slight green fog. Less dense than above, but clearer shadows and distance; no green fog. Distinction very prominent. Shadows veiled ; slight red fog. Shadows clearer, but still some red fog by reflected light. ) No prominent difference be- C tween the two portions; ( fairly good throughout, but ) lacking in brilliancy. Plate G— Portion coated with AgBr+ 6°/oAgI+18°/Agl Ditto, AgBr-180/Ag1+ 6°/ogCl Foggy in shadows and distance; flat, and wanting in density ; green fog abundant. Clearer shadows; better contrast; no green fog; less density in half-tones. I No prominent difference in two portions; green fog through- • out; shadows veiled ; no brilliancy, but plenty of density. ) No prominent distinction; C equally bad throughout; r plenty of density, but shad- ) ows veiled. such latitude in this respect as in the case of iodide. Un like the iodide, chloride does not influence the time taken in fixing. General Conclusions lased upon the foregoing Observations concerning the Influence in Emulsions of Mixed Chlorides and Iodides.—1. With the ordinary pyro developer, iodide should always be in excess of the chloride. When the chlo ride is in excess of the iodide, however, there is apparently a gain in density. Green fog does not appear to be hindered by iodide in presence of chloride, unless the former is present in large excess. 2. With the sulphite developer, green and red fog appear to form readily in presence of chloride, whether iodide be present or not. Pure bromide appears better than bromo- iodo-chloride films, even where iodide is.in excess. Density appears to diminish when iodide is in excess, but when