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The photographic news
- Bandzählung
- 24.1880
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- 1880
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- Bandzählung
- No. 1137, June 18, 1880
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Zeitschrift
The photographic news
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Band 24.1880
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- Register Index 631
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Band 24.1880
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294 THE PHOTOGRAPHIC NEWS. bye 9yotograpkir Sths, Vol. XXIV. No. 1137.-JUNE 18, 1880. CONTENTS. page Photography In and Out of the Studio 289 At Home 290 Hints on Retouching. ByJ.E. Walker 291 Drop Shutters. By W. R. Gowers, 291 A Modified Plan for Developing Gelatine Plates. By W. Bovey 292 Oxalate of Tron in Printing Processes. By M. L. de Koninck 292 The Alkaline Developer 293 Measurement of Actinism. By Dr. R. A. Smith, 293 Working Hours 294 The Development of Under- and Over-Exposed Gelatine Plates 294 Notes 295 Topics of the Day 296 A Photographer’s Holiday. By George 296 French Correspondence. By Leon Vidal 297 Correspondence 298 Talk in the Studio—To Correspondents 300 WORKING HOURS. Although a discussion of some length has appeared in these columns relative to the pay and prospects of assistants, there is one important point, singularly enough, that has escaped the attention of our correspondents. There have been letters complaining of the low rate of pay, and others justifying the moderate wage that falls to the lot of most assistants, but not one word has been said upon the hours or length of time that assistants are required to work. This is a matter of grave consideration both to employer and employe, and sooner or later some definite rules on the subject must come into force. Even a moderate photographic establishment nowadays gives work to several hands of one class or another, and when a change is effected, there is usually an effort on both sides to make better terms. The master possibly thinks that the new assistant may well work a little longer than the last, and the assistant himself hopes to find an easier place than the former one. The consequence is that misunderstandings often arise at the outset, and neither principal nor assistant act fairly towards one another. It would be impossible, of course, to regulate all studios by the same law, because of the wide differences between them in the nature of the business they transact ; but there are certain general conditions upon which an understanding might exist in the case both of London and provincial studios. At what hour in the morning should employes report themselves at the studio ? At what hour in winter or in summer should they be permitted to leave? The duties of first assistant are well defined, since they consist in taking the place of the principal in the studio when the latter is absent; but the work of other assistants and of ladies in the reception room are not, nor can they be, set fast. Usually it falls to the lot of the lady assistant who receives customers to take all cash and to keep the books, in which case her post is obviously very responsible, and one that should secure her the consideration of her employers. But, for all that, punctuality is very essential, as “ A Lady ” points out this week in our columns ; and whether he be printer, mounter, retoucher, or even the lad engaged on odd jobs, it is of the utmost importance in a well-regulated studio that his time of attendance should be fixed and regular. THE DEVELOPMENT OF UNDER- AND OVER EXPOSED GELATINE PLATES. Dr. Eder’s important paper which we published last week on the subject of developing over- and under-exposed plates with the oxalate developer will be read with interest by all photographers, but especially by those who usually treat the gelatine film with this solution. Opinions are still divided as to the value of alkaline pyrogallic and ferrous oxalate for developing the gelatino-bromide film, but so long as it remains impossible to produce an image with out that brown tinge inherent to pyrogallic acid develop ment, the oxalate developer must perforce be made use of invariably in the production of positive pictures, at any [June 18, 1880. rate. For this reason it may be said that while it is optional for the photographer to have the pyrogallic acid developer in his laboratory, the presence of the ferrous- oxalate therein is indispensable. Beyond its rapid action and the absence of ammonia fumes the circumstance that the oxalate developer yields a negative so similar in appear ance and quality to one produced by the wet collodion process will always tell in its favour. An objection has, however, long been lodged against oxalate development, to the effect that plates very much under-or over-exposed cannot be judiciously treated by its means. True, the addition of bromide exerts a retard ing action in the case of oxalate development, as it does in that of the alkaline pyrogallic, but this addition does not satisfy all emergencies; for this reason Dr. Eder’s re searches are just now particularly welcome, and by follow ing the method he prescribes the greatest control can be exercised in ferrous oxalate development. With very much under-exposed plates it is always difficult to cope, but by having recourse to what Dr. Eder terms a “ strong reserve developer ” a film that has received but a small frac tion of its proper lighting may be converted into a good negative. This reserve developer, with a little care, may be kept for months, and any photographer of intelligence can prepare it. It may, in fact, be termed a rapid developer for gelatine plates, but for the present Dr. Eder only re- commends its use for under-exposed plates. It is not difficult of preparation. Into 100 cubic centi metres of water are put 50 to 60 grammes of neutral potassium oxalate, the dissolution of the salt being effected by heat. When dissolved, 17 to 20 grammes of ferrous sulphate, or what photographers usually call protosulphate of iron are added. The latter, if well stirred, will dissolve very quickly under the continued action of heat, and on complete dissolution the resulting red liquid is poured into a well-stoppered flask, where it remains for twenty-four hours. A good deal of potassium sulphate will crystallize out during the time, but none of the active oxalate. A developer prepared in this manner contains not less than twelve or thirteen per cent, of effective ferrous oxalate, and is consequently very energetic in its action, since the ordinary mixed oxalate developer only contains half this amount. After filtering, the reserve developer is poured into small well-stoppered bottles, which must be filled to the top, and will thus remain fit to use for months. It is employed only when a plate has been treated with the ordinary oxalate developer, and this has failed to bring out an image. The ordinary developer is thrown away, and the reserve developer poured over the film instead. Any signs of fogging that may appear are counteracted by the use of bromide as in ordinary development. The treatment is therefore of the simplest, and consists (nly in the employment of a strong instead of a moderate devel oper. In the case of over-exposed films, although the addition of bromide does permit one to control to a certain degree, Dr. Eder recommends a method of manipulation which does not involve the use of the full amount of iron at first. Supposing you have the saturated solutions (saturated, of course, cold) of potassium oxalate and ferrous sulphate at hand, you measure off as usual three volumes of the first and one of the second, but you do not mix them. You add, at first, but a few drops of the iron solution to the three volumes of potassium oxalate, and commence the development with this, and without the addition of any potassium bromide. If the image does not appear, then you add still more of your iron, until the whole amount measured off has been expended. As you add your iron, and perhaps also a little potassium bromide solution, you will find the vigour of your image increase. Many plates, says Dr. Eder, of the less sensitive description require no potassium bromide, as it causes them to become too hard ; but with sensitive plates more or less bromide must be used to make them sufficiently clear and vigorous. Plates that have received twently times their proper exposure may be thus successfully treated by the oxalate developer.
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