132 



THE AMERICAN MONTHLY 



[July, 



2. An alkaline developer, strong in 

 ammonia or alkali, tends to bring'out 

 details in the shadows. 



3. A developer, strong in pyro or 

 iron, and containing sufficient re- 

 strainer (2) to prevent general fog, 

 gives strong contrasts and density. 



From this it may be readily under- 

 stood that : — 



I . For an under-exposed plate a 

 slow development is required. In 

 using oxalate do not add more than 

 I part of iron to 16 of the oxalate 

 (even i to 20 might be better to be- 

 gin with) , and allow development to 

 proceed slowly until as much detail 

 is out as can possibly be obtained. 

 Then add more iron, making the 

 proportion i-S, if necessary, to ob- 

 tain density. In using pyro. begin 

 with less than the usual quantit}' of 

 pyro, but use moi^e alkali, and let 

 the detail come out slowly. Then 

 if density is required, more pyro 

 should be added. Another plan is 

 to dilute the usual developer with 

 half its bulk of water, or more ; but 

 the addition of ammonia tends to 

 bring out detail without giving 

 density, and this is what is required 

 in an under-exposed plate. For the 

 tendency in such a plate is toward 

 densitv in the well lighted parts and 

 transparency in the shadows. By 

 using a weak developer, however, and 

 giving time enough — it ma v require an 

 hour or several hours — the feeble 

 effect of the light in the shadows 

 may be made to show, while the 

 better lighted parts do not become 

 dense, as they would with a normal 

 developer. The reduction of the sil- 

 ver, once started by the weak dcA-el- 

 oper, may then be continued by the 

 stronger one, while, had we begun 

 with the strong developer, the well 

 lighted parts would probably be fully 

 developed and perhaps quite opaque 

 before the details in the shadows be- 

 gan to show. 



We have thus conscientiovisly de- 

 scribed the proper method of treating 

 under-exposed plates ; but lest we 

 should be numbered among the many 



amateurs who, by their great skill, 

 have made wonderful works of art out 

 of under-exposed plates, we may add 

 that the method described is not the 

 one we are accustoined to adopt in 

 practice. Our plan is, wherever we 

 have a plate evidently under exposed, 

 to immediately throw it away. This 

 plan saves much time and labor. It 

 is true, sometimes a good picture can 

 be made from a slightlv under-timed 

 plate ; but it is impossible to make a 

 good picture unless the light has acted 

 long enough to impress the details on 

 the plate so that the developer can 

 bring them out. 



2. For an over-exposed plate a 

 strong and well restrained developer 

 is required, for in this case the ten- 

 dency is toward flatness and want of 

 contrast. This is due to the fact that, 

 when the light acts too long upon a 

 plate, development gives a thin image. 

 Up to a certain point of exposure the 

 development gives increasing density, 

 but beyond that point the reverse ac- 

 tion takes place. For this reason the 

 sky over a landscape, the brightest 

 part, is frequently quite thin, owing to 

 over exposure, while the remainder 

 of the picture is strong. In fact, by 

 giving an excessively long and cor- 

 rectlv timed exposure a positive pic- 

 ture may be taken in the camera. 



A good formula for developing an 

 over-exposed plate is i part of iron to 

 6 or 8 of oxalate, with about 5 drops 

 of bromide to each ounce of de- 

 veloper. The quantitv of bromide 

 must be regulated by the require- 

 ments of each case — it must be suffi- 

 cient to control the development. 

 When pyro is used, put in twice the 

 usual quantity of pyro. rather less 

 alkali than usual, and a good excess 

 of bromide. vSome operators advise 

 that plates known to be over exposed 

 be placed in a plain bromide solution 

 for a few moments before de\elop- 

 ment. We have not tried this plan 

 because we have not yet discovered a 

 means of knowing that a plate is over 

 exposed ; however, there maj- be an 

 advantage in the proceeding, for the 



