The Project Gutenberg EBook of The Barnet Book of Photography, by Various This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org Title: The Barnet Book of Photography A Collection of Practical Articles Author: Various Release Date: August 9, 2012 [EBook #40468] Language: English Character set encoding: ISO-8859-1 *** START OF THIS PROJECT GUTENBERG EBOOK THE BARNET BOOK OF PHOTOGRAPHY *** Produced by RSPIII and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive/American Libraries.) THE BARNET BOOK OF PHOTOGRAPHY. THE BARNET BOOK OF PHOTOGRAPHY. A COLLECTION OF PRACTICAL ARTICLES BY CAPT. W. DE W. ABNEY, C.B., F.R.S., ETC. CHARLES H. BOTHAMLEY, F.C.S., F.I.C. CHAPMAN JONES, F.C.S., F.I.C. HAROLD BAKER A. HORSLEY HINTON JOHN H. AVERY W. THOMAS ANDREW PRINGLE JOHN A. HODGES, F.R.P.S. REV. F. C. LAMBERT, M.A. W. ETHELBERT HENRY, C.E. JAMES PACKHAM, F.R.P.S. THO'S. S. SKELTON page decoration THIRD EDITION. Published by ELLIOTT & SON, BARNET, HERTS. Percy Lund, Humphries & Co., Ltd., 3, Amen Corner, London, E.C. — 1898. Publisher Logo CONTENTS OF THE BOOK. Page. Alpine Photography. W. de W. Abney, C.B., F.R.S. 9 Negative Making. C. H. Bothamley, F.C.S., F.I.C. 23 Lenses. Chapman Jones, F.C.S., F.I.C. 57 Portraiture. Harold Baker 77 Pictorial Photography. A. Horsley Hinton 87 Architectural Photography. John H. Avery 117 The Hand Camera and Its Use. W. Thomas 131 Lantern Slides. Andrew Pringle 141 How to Make Enlargements. John A. Hodges, F.R.P.S. 155 P.O.P. Rev. F. C. Lambert, M.A. 177 Platinotype Printing. A. Horsley Hinton 197 Contact Printing on Bromide Paper. W. Ethelbert Henry, C.E. 225 The Gum-Bichromate Process. Jas. Packham, F.R.P.S. 241 An Introduction to Carbon Printing for Beginners 253 The Carbon Process. Thomas S. Skelton 261 ILLUSTRATIONS. Homewards. Karl Greger 17 5 Among the Alps. W. de W. Abney 25 Winter Time on the Alps. W. de W. Abney 41 Melton Meadows. A. Horsley Hinton 72 Miss Lily Hanbury—A Portrait. Harold Baker 89 Gather the Roses while ye may. Alex. Keighley 121 Birch and Bracken. W. Thomas 137 Drifting Storm Clouds. W. Thomas 168 Streonsalch. W. J. Warren 201 Cupboard Love. T. Lee Syms 232 At the Fountain. J. W. Wade 265 PREFACE. The purpose of this book is to place in the hands of every Photographer instructive articles on essential processes and manipulations, by eminent writers who have given such subjects their especial study, and who have borne in mind that whilst the experienced Amateur and the Professional may each find much to learn from a comparatively elementary description of methods and means, it is the Beginner who stands in greatest need of help. In the mind of every photographer the name of Barnet is inseparable from a great Photographic Industry, and now it is intended that the name shall be associated with a good and useful book, which is called the Barnet Book of Photography, and it is left to the reader to say if the fulfilment of its purpose and the manner of its doing are such as to justify its existence. To all who are interested in photography, who love it for itself and for its productions, and who desire to improve their own practice of its many processes and applications, this Book is respectfully dedicated. Barnet, Herts. ELLIOTT & SON. April, 1898. 7 8 A Famous Pike Stream COPYRIGHT. NEGATIVE BY W. L. F. WASTELL. A FAMOUS PIKE STREAM. Contact Print on BARNET PLATINO-MATT BROMIDE PAPER. Alpine Photography. Writing in London on a day in winter with a murky sky and sloshy streets, the title of Alpine Photography is verily refreshing. It brings back days of sunlight and joyous experiment, and as we write the soul stirring scenery is before us called up by photographs taken under varying conditions of comfort and discomfort. That there is something different in Alpine photography to photography in our own country, we are bound to believe, since a special article is demanded for it. The first question invariably asked is as to the nature of the outfit required. We should here like to divide our reply into two divisions. The one concerning the mountaineer, and the other the ordinary tourist. For the former we have no doubt in our minds that a hand camera to take ¼ plate or 5 × 4 pictures is the most convenient form of camera to take. It is not our business to advertise any person's wares and we shall content ourselves by saying that personally we prefer a camera which has separate slides and does not possess a magazine, more particularly when glass plates are to be used, though a form of Kodak is not to be despised. But perhaps we are prejudiced in favour of glass plates, for they are simple to manipulate and have no cockles nor other drawbacks which the careless photographer may have to encounter. Probably the most useful lens to employ is a doublet of which the focal length is about a quarter more than the width of the plate, since it includes a fair angle and the margins of the photographs are not likely to be markedly different in general density to the centre, as is the case when wide-angle lenses are employed. In England a lens which will cover with a large stop, say f/8, is a desideratum, but in the Alps it is very rarely that such a large ratio of aperture to focal length is required. As a rule for ordinary plates a lens has to be stopped down to f/16 to give a negative in say 1/50th of a second. Nevertheless where orthochromatic plates are to be employed it is very necessary to have a lens which will cover a plate satisfactorily with f/8 in order to use a colour screen for producing orthochromatic effects, since the loss of photographic light caused by the screen can only be compensated for by such an aperture even when the shutter is slowed down. The reader is therefore recommended on the whole to 9 10 furnish himself with one of the modern lenses which work at f/8, though he must remember that the larger the aperture employed the more the margins and centre of the picture will suffer from unequal exposure. With some hand cameras there is a means of attachment to a stand, but a stand on a mountain is difficult to use and moreover has on more than one occasion been proved dangerous to carry. The mountaineer if he desires to give a time—and not an instantaneous—exposure on his excursion, would do well to have a small clip ready to attach to the head of his ice axe. The axe will form a sufficiently stable stand for the more prolonged, but still short, exposure that he may be required to give on some particular subjects such as a photograph at sunrise or near sunset. Photographers in England are rarely afflicted with breathlessness through exertion, but it is different in mountaineering. A mountaineer may keep his wind, but it would be rare to find that his heart was beating equably after some spurt of exertion, such as rock climbing. It is often after some such exertion that he comes upon some view which he may wish to record on his photographic plate. The usual method of holding the hand camera would under such circumstances prove a failure so far as sharpness of image is concerned. Pressed against his "middle" or "upper" chest, the beatings of the heart will record themselves on the photograph. Under such circumstances resort must be had to some form of support on which to rest his camera. After many years' experience, the writer has come to the conclusion that there is no support superior to the ice axe. It is not necessary to cause it to stand upright in the ground, ice, or snow, though this should be done if possible. It will suffice to rest the point on the rock, and place the camera on the axe head, with the pick parallel to the body. We then have a firm support in one direction, and the hands, which are not affected by the automatic motion of the heart, can be trusted to keep it steady in the other direction. Photographs taken with a good lens, and with such a stand, will bear enlarging up to 22 inches, at least. It is because these photographs will bear enlarging that a small plate is recommended to the mountaineer. There is not a large proportion of Alpine views taken on the mountain side of which one would care to have anything but a memorandum, and it is such a size as that recommended which gives such a memento, and which, if desired, allows a more formidable size to be acquired at home, where we may suppose there are all the conveniences that a photographic laboratory affords. The writer has had experience on mountains with cameras varying from 12 × 10 to the ¼ plate size. When younger and more inclined to waste a few valuable minutes of daylight in putting up a camera stand, the 12 × 10 gave pictures which we often lamented having taken, whilst in his more mature years, a snap-shot has never been regretted. The cameras which require stands, require one porter at least to carry them, for although the late Mr. Donkin carried his own 7½ × 5 camera up the highest peaks, it is few men, who, even if they had the energy or the physique that he had, would imitate his example. A porter means an extra expense in fees, and an extra mouth to feed, and very likely entails slowness in a climb through having an additional man upon the rope. A quarter plate or a 5 × 4 camera the owner, however, can himself carry; but the best form of attaching it to his body has been a difficult task to evolve. Many and many different attachments have been tried. One thing is quite certain, and that is, the camera should be in a stout case, but it cannot be carried over the shoulders by a strap as we can do in comparatively level countries. Let anyone try to come down a rock with the camera slung over his shoulders, and he will soon find it dangling in front of his stomach, or swinging like a pendulum, and threatening to displace him from what at best may be a treacherous handhold. The method of attachment we adopt now, will be readily seen from the diagram. Knapsack Carry Method The shoulder strap is utilized, but a ring is attached to the back of the case as shown, and a strap or piece of whipcord comes over the strap as shown. The two shoulders are in AA and the case is carried as a knapsack. The length of the cord or strap BB is so adjusted, as is also the length of the shoulder strap, that the camera lies against the small of the back, and that it will not swing away from the body. At one time the ring was placed in front of the case, but the result was merely to cause the top of the case to rest against the back. The plan shown above has answered under almost every variety of circumstances, and the weight is inconsiderable. (A friend has his camera attached to the bottom of a small "rücksac" and this answers, but as the writer does not carry his own provisions or change of garments he has not adopted this plan). A long day's march may be undertaken if this contrivance be employed, and the weight is scarcely felt. For those who have not had extensive practice with hand cameras, a view finder is, if not a necessity, at all events, a great help. On the whole, perhaps the best form is that in which a miniature view falls on a ground 11 12 13 14 glass. It must be recollected, however, that each view finder is adapted for some particular focal length of lens. The view in the finder and on the plate should be compared, and if the former is more extensive, the surplus ground glass should be covered up with a black mask. If it be determined to take a camera with its stand, very few directions are required beyond those which apply to ordinary view work on the plains. It may perhaps be as well to mention that a camera stand placed on ice or snow, is not immovable until the iron shoes of the legs attain the temperature of the surrounding snow or ice. An exposure of a few seconds will often show an image which has moved on the plate. The next point that we may call attention to is the plate to be employed. With a hand camera there is no absolute necessity to have the most rapid plate, as far as exposure is concerned, but in mountain work it must be recollected that there are very great contrasts to represent on the print. "The slower the plate the steeper the gradation" is almost axiomatic, and it must be recollected that only a certain amount of opacity will print if the deepest shadows only are to be kept of the greatest black obtainable in a print. It is evident that the greater the range of light and shade that is obtained of a printable density, the more true to nature the picture will be. For this reason a quick plate with a moderate gradation is to be preferred—as being most generally useful—but it should be a plate which is absolutely free from fog, and it should also be of as fine a grain as possible, the size of which has something to do with development. This is still more true when a camera stand and hand exposures are made. With a slow plate with feebler intensities of light, which must be the case when the lens is stopped down to admit of hand exposures, the gradation becomes more steep than if a fairly bright light be employed. A quick plate does not suffer in the same way, however small the stop may be. It has already been stated that isochromatic plates may be employed with a hand camera. For ice and snow views there is not much to commend their employment, unless to give a deeper shade to the sky and to the vast crevasses which so often form part of the foreground. The darker sky allows faint clouds to be visible in a print when they otherwise would be absent. Pictorially thus the isochromatic plate has something to recommend it. Celluloid films have often been substituted for plates by the writer, and excellent photographs have been obtained on them when they were fairly rapid. There is not much to be said in their favour as regards weight, for in most cameras the support for them weighs nearly as much as the glass plate. There is also a disadvantage in developing them, for they are not so easily manipulated as a rigid body. For convenience in travelling, however, they are to be highly commended. A gross of cut films do not weigh so much as a dozen plates and occupy much less space in the baggage. The question of the use of a Kodak camera with its roller slide, has not been brought forward, not because excellent results cannot be obtained with it, but simply because the writer prefers to use plates and films which can be got at any time for the purpose of development. For travelling on the continent, and to one's mountain destination, experience has shown that a small hamper is the safest receptacle of all the necessary kit. A hamper which will contain two camera cases side by side is really sufficient; but it should be a little greater in depth. It may be thought that two cameras are to be taken, but such is not the intention. If a zinc trough be made of the size of one camera case it will contain all the developing apparatus necessary, the lantern, and the plates or films, and all the few etceteras which go to make one happy. (A screwdriver, a file, and some extra screws, and gummed paper and white blotting paper cut to the size of the plates should be enough for the etceteras). The hamper may be arranged so that the camera and view finder may be taken out without any derangement of the rest of the articles in it. The developing bottles and cups, with the dishes, may be similarly extracted. This prevents undue trouble in unpacking and packing. One grand thing to remember is, pack well but not distressingly tightly, in other words don't employ an expert packer if you wish for comfort. Have the hamper a size too large rather than a size too small. Also be it remembered that it is useless to stopper the bottles with all sorts of devices at home, and have to pack in an ordinary manner when once the contents of the hamper have been brought into use. Have your bottles covered with an indiarubber cap which can easily be removed and replaced; of course we are assuming that development is to take place during one's travels, and not to be left over for home. Personally we think that a speedy development after a view is taken will give the best picture. It may often happen that an undeveloped sensitive plate or film will suffer by its travels. There will or may be scratches and what not, which would be absent if the negative is finished at the time. The outfit for development which need only be taken is as follows: four developing dishes, bottles or cartridges of the dry developer, ammonia diluted to half its strength in a glass stoppered bottle (if in a wooden case, as for medicine bottles, it will be a further protection), a couple of tins of hyposulphite pounded up before the journey, carried in small tins (such tins as the half-plate platinum paper comes in are very convenient), two or three empty six ounce medicine bottles with good corks, a two or four ounce measure, a washing rack with a trough (there is a folding rack in the market which answers admirably; it has v shaped grooves which never damage the edges of the film, and one rack will take twenty-two glasses back to back). A zinc trough can be made to cover the plates with water when in the rack, a lantern (by preference a paper folding one), a dusting brush, a couple of dusters, and blotting paper cut into squares the size of the plates, with which to pack them—it is useful also to have spare pieces of blotting paper to place beneath the plates when drying, also a piece of mackintosh to place on the wash stand during developing operations—an empty pint wine bottle will be got at any hotel and in this the 14 15 16 17 hyposulphite can be dissolved. The list looks formidable but the whole can be readily packed in the hamper of the size given. It will be seen that no intensifying solutions are enumerated amongst the requisites. A negative is better strengthened in the quiet of one's dark-room at home. Homewards HOMEWARDS. KARL GREGER. Now we must give a hint or two as to the exposures required. We will suppose that on the plates to be used a satisfactory negative of an open English landscape, on a bright June day with fleecy clouds in the sky, can be secured with an aperture of f/11 in 1/25th of a second. If that be so, then on an equally fine day in July or August, at an altitude of about 6000 feet, the same kind of view should theoretically be secured in 1/50th second, and a stop of f/16—that is, the photographic light is about four times as strong. It must, however, be recollected that at this altitude, and particularly near mid-day, the shadows are not illuminated to the same degree from the sky. The darker blue sky shows that the light which at a low altitude goes to make a pale blue sky is to be found in the direct rays of the sun, and not scattered to give a luminous sky. As the shadows are principally illuminated by the light from the sky, it follows that the shadows will be darker at a high than at a low altitude, for this reason amongst others, the exposure should not be curtailed to the amount given above. If the aperture be reduced to f/16 it is probable that the exposure of 1/25th second will be not more than sufficient to give. For our own part we prefer to give longer and to expose well for the deep shadows, trusting to development to give us properly "gradated" pictures. As the sun goes down toward the horizon, the shadows get more illumined from local reflection, and it is scarcely necessary to alter the exposure until considerably nearer sunset than at home, when the exposure must be considerably prolonged. For views in which there is little but ice and snow, the exposure should be very much curtailed. There is so little contrast that if the exposure be at all prolonged the picture will be inevitably flat. The shadows are illumined by an immense quantity of light reflected from the white surface, and the difficulty is to get sufficient contrast. The writer well remembers one set of beautiful views, taken from the top of a mountain some 10,000 feet high, where the eye could see nothing but snow-fields and ice and swirling masses of clouds. The day was not bright, but to get a satisfactory picture a stop of f/32 was necessary with only an exposure of 1/70th of a second. Plates given an exposure of 1/25th second with a stop f/16 showed little besides a plain white mass. It would be difficult to give hints for every kind of view. The judgment of the operator must be brought into play and no actinometer will be of much use under the varied conditions which are the rule, not the exception. Now as to development. The "one-solution" given by the metol and amidol cartridges are the most readily prepared, and in five times out of six will scarcely be bettered, but for the sixth time may fail, because of 18 19 their "rigidity." For these exceptional negatives, solutions of an oxidizing agent such as pyrogallol, of a restrainer (bromide), and of an accelerator are to be recommended. For the latter, the carbonate (not the bicarbonate) of potash is much to be recommended, though some prefer ammonia. Two formulæ are given, either of which will be found extremely useful. When the exposure has been prolonged enough for details in deep shadows to be brought out, it will generally happen that over-exposure has been given to the high-lights, and it is to keep these in the printing state that care is required. In the old collodion dry plate days, it was very usual to bring out a complete phantom image of a subject before any density was given to it. When this was properly out, the intensifier of silver nitrate and pyrogallol was applied, and the picture gradually brought up to printing density. It was usually full of detail in the high-lights and shadows, all of which would be found in the finished print. Such is the same procedure which we recommend, strive to get out an image of feeble density but full of detail, and then give the density. The plate should first of all be thoroughly soaked in a solution of the alkali which can be used, and then a few drops of the pyrogallol solution be dropped into the developing cup with an equal number of drops of the restrainer. The alkaline solution is then returned to the cup and again poured into the dish and over the plate. By degrees the required phantom image will make its appearance, and now bromide and pyrogallol are added until it is evidently complete. The plate is then washed in water, a final wash being given in a very weak solution of acetic acid or citric and water. After a final rinse with water the plate is treated with the pyrogallol solution and restrainer in the proportion recommended for the ordinary development of the plate, omitting the alkali. The density will begin to appear, and when it flags, a little alkali is added (a few drops at a time) to the solution. Keep the image fairly feeble at above half the proper printing density, and fix. The plate should then be kept for intensification, preferably by Mr. Chapman Jones's, when a mercury solution is applied, and then a ferrous oxalate to reduce the latter to the metallic state. It will be found if this procedure is adopted, that the negative is built up with a greater range of light gradation than by bringing it out by a one-solution method of development. If one wishes to exercise artistic treatment, then in the preliminary stage more importance can be given to any desired part by applying a camel's hair brush soaked in normal pyrogallol solution with its restrainer. The prominence thus gained will be kept in the subsequent operations. When applying the brush care must be taken that the image blends as it were with the rest of the picture. No abrupt increase of density must be permitted, as if it be, the result will be anything but satisfactory. The following is an ammonia-pyro developer, with which the writer usually works. A Ammonia 1 part. Water 9 parts. (Of course, should the ammonia be taken half strength allowance must be made for the dilution.) B Potassium bromide 20 grains. Water 1 ounce. (When travelling it is very convenient to have the bromide weighed out into 20 grain packets.) P Pyrogallol dry. S Saturated solution of sulphite of soda. When the view has strong contrasts and the plate has been exposed for the shadows take of A 30 minims and 2 ounces of water and soak the plate in it as given above. Then add to the cup, of B 2 drams, of S 1 dram, and about quarter grain of P. Pour back the solution of ammonia from the dish, and then apply the mixture till all detail appears, and proceed as indicated above. A saturated solution of potassium carbonate may be substituted for the ammonia solution. Before closing this chapter it may be of use to the reader to tabulate the number of thicknesses of atmospheres through which light has to travel at different altitudes of the sun at sea level. Altitude. Atmosphere. 90° 1.000 80° 1.015 70° 1.064 60° 1.155 50° 1.305 40° 1.555 30° 1.995 19 20 21 20° 2.904 15° 3.809 10° 5.571 5° 10.216 4° 12.151 2° 18.882 0° 35.503 If sunlight outside the atmosphere be represented by 1 and say 1/10th be cut off by 1 atmosphere, then after transmission through 2 atmospheres only .81 will reach the spectator, and if through 3 only .729. For any atmosphere the diminution will be 1/10th, that is, it will be .9x where x is the number of atmospheres. If we ascend the factor varies, there are less thicknesses of atmosphere to go through and we get the following table. Barometer in Inches. Visual Transmission Sunlight outside the Atmospheric being 1). Photographically Actinic Light Transmitted (Sunlight outside the Atmospheric being 1). 30 .853 .639 29 .866 .654 28 .875 .672 27 .884 .689 26 .891 .708 25 .899 .730 24 .908 .746 23 .915 .763 22 .922 .787 21 .928 .800 20 .934 .819 19 .940 .833 This table and the preceding one will enable a calculation to be made as to the exposure to be given. Thus at sea level with a photographic brightness of sun of 639,000 candles when nearly overhead, it will at 5° above the horizon only have a photographic brightness of about 1000. At about 9000 feet high the photographic brightness would when the sun is overhead be about 800,000 candles, and at 5° it would have a value of 350,000, showing the greater penetration through the thinner atmosphere. W. de W. Abney, C.B., F.R.S., etc., etc. Negative Making. DEVELOPMENT, INTENSIFICATION, REDUCING, Etc. When a sensitive plate has been properly exposed under ordinary conditions, there is no visible change. The action of light produces what is known as a latent image or developable image, and in order to convert this into a visible image with sufficient opacity to be useful for printing purposes, it must be developed. In the operation of development, the plate is treated with some solution that will act on the exposed parts of the sensitive film and reduce the silver salts contained therein to metallic silver, in quantity proportional to the amount of light-action, whilst at the same time it produces no appreciable change in those parts of the film on which light has acted the least or not at all, and which correspond to the darkest shadows of the object that has been photographed. The solution used for this purpose is called the developer. DEVELOPERS—GENERAL. The substances that can be employed as photographic developers are now somewhat numerous, but the 22 23 24 most useful for negative making are pyrogallic acid (also known as pyrogallol, or for brevity as pyro.), ortol, metol, and hydroquinone (also known as quinol). Ferrous oxalate is likewise used in special circumstances, but not for general work. An ordinary developer as mixed for use contains:— 1.—One of the above-mentioned substances (pyrogallic acid, ortol, metol, quinol) which is the actual developing constituent, and is known as the reducer, but requires the addition of the next constituent before it can work. 2.—An alkali, which may be sodium carbonate, potassium carbonate, caustic soda, caustic potash, or, if pyrogallic acid is used, ammonia. The alkali sets the reducer in action and is called the accelerator. 3.—A soluble bromide, which must be potassium bromide except when ammonia is used as the alkali, and then it may be ammonium bromide. The chief use of the bromide is to retard the action of the developer, and in particular to prevent its affecting those parts of the film that have not been acted on by light. For this reason the bromide is called the restrainer or, sometimes, the retarder. 4.—A sulphite, the function of which is to prevent the solution from becoming strongly discoloured and consequently staining the film. It also affects the colour of the reduced silver that forms the developed image, this colour being browner, and consequently of higher printing opacity, the lower the proportion of sulphite present. Sodium sulphite and potassium metabisulphite are the most commonly used. The composition of a developer has to be so arranged that, whilst reasonably rapid in its action, it is not so rapid as to be beyond control, and does not produce "general fog" by acting on those parts of the film that have not been acted on by light. among the alps AMONG THE ALPS. CAPT. W. DE W. ABNEY, C.B., F.R.S. Etc. DEVELOPMENT—GENERAL OPERATIONS AND PHENOMENA. A developer is usually compounded immediately before use by mixing two or more solutions, and in order to ensure uniform action it is essential that the constituents should be thoroughly mixed before the liquid is applied to the plate. If the measuring or mixing vessel is large enough, this can be done by agitating the liquid; if not, the liquid may be poured once or twice from one vessel to another. The quantity of developer necessary for a plate of a given size depends in some degree upon the size and character of the dish that is used, and is smallest when the bottom of the dish is quite flat and has no ridges or grooves. It is false economy to use too small a quantity, and it may be taken that for a quarter plate 1½ oz., for a half plate 2½ or 3 oz., and for a whole plate 4 oz. of developer should be used. Ebonite, xylonite, or papier maché dishes are the best for all operations connected with negative making, since they are not so liable as porcelain or earthenware to break a plate if it is allowed to drop into them. When applying the developer to the plate it is important to cover the whole surface of the plate rapidly and 25 26 in such a manner as to avoid the formation of air bubbles, and the best way is to begin to pour on the developer at one corner of the developing dish and whilst pouring somewhat quickly move the vessel rapidly but steadily along the edge of the dish to the other corner. If there should be any froth or air bubbles on the surface of the developer, the last portions should not be poured out of the vessel into the dish, and then the risk of air bubbles forming on the surface of the plate will be lessened. Sometimes after the developer has been poured on and the plate seems to be uniformly wetted, the liquid will recede from one corner or one edge of the plate and the part thus left uncovered will appear as a patch of lower opacity when the negative is finished. This happens either because the dish is not standing level on the table or because the bottom of the dish is not flat; sometimes it happens because too small a quantity of developer has been used. After the plate has been covered by the developer the dish should be carefully rocked from time to time, and, for reasons that will be explained presently, the time required for the first appearance of the image and the manner in which the different parts of the image follow one another, should be carefully observed. If the plate has been correctly exposed, the brightest parts of the image will appear (as black, of course,) in about a minute, more or less, according to the temperature, composition of the developer, and character of the plate, and the other parts will follow steadily in the order of their brightness, after which the image as a whole will continue to gain vigour or opacity up to a certain limit. The essential point is that the principal details in the deepest shadows of the subject shall appear and acquire a distinct printable opacity, before the highest lights become so opaque that the details in them are no longer distinguishable. Whether this condition is realisable or not depends very largely on the exposure that the plate has received. If the image appears in considerably less than a minute and the different parts follow one another very quickly, the plate has been over-exposed, and the degree of over-exposure is indicated by the rapidity with which the image appears. In this connection it ought, however, to be stated that with metol and certain other developers, even when the plate has been correctly exposed, the different parts of the image appear almost simultaneously, though the first appearance may not begin until about a minute after the developer has been applied to the plate. It follows that with these developers it is difficult to recognise over-exposure, but it so happens that they are not suitable developers to use when there is any probability that the plates have been over-exposed. On the other hand, if the image is slow in appearing and the brightest parts of the subject are not followed in due course by the middle tones, the plate has been under-exposed, and there is considerable danger that the high-lights may become quite opaque before any details have appeared in the shadows, or even, in extreme cases, in the lower middle tones, that is to say, in those parts that are next in darkness to the shadows. When it is desired, as it frequently is, to alter the composition of the developer during development, the substance or substances to be added should be put into the measuring or mixing glass, the developer poured out of the dish into the glass, and the well-mixed liquid poured over the plate as before. Any attempt to add substances to the developer whilst it is in contact with the plate will probably result in uneven action. It should be borne in mind that temperature has an important influence on development, the time required for the first appearance of the image and for the completion of development being, as a rule, less the higher the temperature. Further, if the developing solutions are very cold, it is often almost impossible to obtain sufficient opacity. Perhaps the most difficult thing in connection with development is to know when to stop the process, that is to say, when the image has acquired sufficient opacity, or "density," as it is often called. After all the required detail has become visible, the plate from time to time is lifted carefully out of the developer, allowed to drain for a moment or two, and then held between the developing lamp and the eye; the opacity of the image, especially in the highest lights and deepest shadows, being carefully scrutinised. The appearance of the image as seen when looking at the back of the plate, is also carefully observed. For this purpose it is very much better that the light of the developing lamp should pass through transparent glass (ruby or deep orange) so that the flame itself is distinctly visible, instead of through ground glass or a coloured translucent fabric. Further, the flame of the lamp, whether gas or oil, should always be turned up to the same height, for it is clear that if the brightness of the flame used for making the examination is not fairly constant, all sorts of variable results will be obtained. For this reason it is much better to judge the opacity of negatives by artificial light than by daylight, the intensity of the latter being so variable. A paraffin lamp with a circular wick and a deep ruby chimney with a metal cap at the top, answers admirably. No general rules can be laid down; the appearance of the properly developed image depends on the thickness of the film, the granularity of the silver salt, the presence or absence of silver iodide, and the composition of the emulsion used. Experience only is of value, and the best way to secure uniformly satisfactory results, is to keep as far as possible to one brand of plates. With some plates, for example, very little of the image should appear at the back of the plate, with others the greater part of the image must be distinctly visible there. 27 28 29 Sometimes, especially when using small sizes of plates, it is not easy to tell whether all the necessary detail in the shadows has been brought out, and this is an important matter, for if the small negatives are to be used for making enlarged negatives or prints, or lantern slides, there should be very little clear glass indeed even in the deepest shadows of the subject. As a rule it may be said that when every part of the image is at least gray the maximum possible amount of detail has been brought out. If the greyness begins to spread to the margins of the plate where it has been protected by the rebate of the dark slide, general fog is being produced, and, as a rule, little will be gained, but much may be lost, by continuing the development for any considerable time after this is observed. When development is completed the developer is poured off, the plate is well rinsed under the tap or in two or three changes of water, and is then ready for fixing. DEVELOPMENT WITH PYRO-AMMONIA. This method of development has the advantage that the constituents can be kept in concentrated solutions, considerable modifications in the composition of the developer can be made very readily and the negatives obtained are of excellent printing quality. On the other hand it cannot be satisfactorily employed with certain brands of rapid plates, because with them it has a tendency to produce general fog, and with some other plates, especially when they are old, it has a tendency to produce what is known as green fog. Three solutions are prepared:— Reducer. Pyrogallic acid 1 oz. or 10 parts Potassium metabisulphite1 1 oz. or 10 parts Water, to make up to 10 oz. or 100 parts Accelerator. Ammonia 1 oz. or 10 parts Water, to make up to 10 oz. or 100 parts Restrainer. Ammonium bromide 1 oz. or 10 parts Water, to make up to 10 oz. or 100 parts The metabisulphite is dissolved in about 8 oz. (80 parts) of water with the aid of heat, and the pyrogallic acid is then added. When the liquid has cooled it is made up to 10 oz. (100 parts) by addition of water, the whole being well mixed by shaking. For each ounce of developer, take 20 minims of reducer, 20 minims of restrainer and 40 minims of accelerator, and make up to 1 oz. with water. With some plates 60 minims of accelerator and 30 minims of restrainer may be used, but any greater proportion of accelerator has considerable tendency to produce general fog. On the other hand the proportion of restrainer can often be increased with advantage since, unless the amount added is very large, its chief effect is to prevent general fog; 30 minims of restrainer to 40 minims of accelerator, or 40 minims of accelerator to 60 minims of restrainer are proportions that can be recommended. Too low a proportion of bromide should be carefully avoided. It is very important to ascertain, by careful trial with each brand of plates that is to be used, what is the maximum proportion of ammonia that can safely be added, and what proportion of bromide to ammonia is necessary in order to prevent general fog. As a rule, the more rapid the plates the smaller is the quantity of ammonia that can be used with safety. By far the best plan is to keep development well under control by adding only part of the accelerator at the beginning of development and adding the rest as circumstances require. For each ounce of developer take 20 minims of pyro solution and make up to the required bulk with water. In another measure mix for each ounce of developer 40 minims of bromide solution and 60 minims of ammonia solution, and regard this as the maximum quantity that can be added with that bulk of developer. Now to the diluted pyro solution add about a quarter or one-third of the ammonia and bromide solution, pour this mixture on the plate and observe what happens. If the mode of appearance of the image indicates that the plate has been correctly exposed, about half the remaining ammonia and bromide mixture may be added to the developer at once, and the action allowed to continue, with occasional rocking of the dish. If development proceeds satisfactorily and, in particular, if the chief details in the shadows begin to appear before the highest lights have become too opaque, it is not necessary nor advisable to add the last portion of the ammonia and bromide mixture, since the tendency to general fog and green fog is reduced when the proportion of ammonia is kept as low as possible. On the other hand, if the development flags and the appearance of shadow detail is a little tardy, the rest of the 30 [1] 31 teasels Teasels By Carine Cadby. ammonia and bromide mixture must be added. If the plate seems to be over-exposed, no more of the ammonia and bromide mixture should be added for some time, until it is seen whether the quantity already in the developer will suffice to complete development. If it seems that the over-exposure has been considerable, a further quantity of pyro solution (10 to 20 minims per oz.) and also of bromide solution (10, 20, or 30 minims per oz.) may be added with advantage. Development is then allowed to continue and the negative is examined from time to time; if it is seen that the opacity does not increase, or if sufficient detail in the deep shadows does not appear, further small quantities of the ammonia and bromide mixture may be added cautiously until the required result is obtained, waiting a little while to see the result of each small addition before adding more. When the plate behaves as if under-exposed, dilute the developer at once with half the quantity or an equal quantity of water, according to the degree of under-exposure indicated, and add the whole of the ammonia and bromide mixture. These modifications should check the rate at which the high-lights of the subject gain opacity, whilst accelerating the appearance of the middle tones and shadows. Should this effect not be produced, further quantities of ammonia and bromide mixture may be added or, in extreme cases, ammonia alone, and the developer may be still more diluted with water. If any considerable parts of the image still show no detail, local development with a brush may be tried as a last resource. A soft camel's hair brush, preferably mounted in quill, is used. Some of the ammonia and bromide mixture is placed in a vessel and diluted with two or three times its volume of water. One corner or edge of the plate is raised so that the part to be treated is lifted out of the developer, the diluted ammonia and bromide mixture is applied rapidly with the brush, and the plate is allowed to drop gently back into the developer. The treatment may be repeated if necessary. Should all these devices fail, the plate is hopelessly under-exposed. Sometimes, when working with a diluted developer as just described, it happens that although all the necessary detail has been brought out, the image gains in opacity very slowly. Provided that all the required detail is visible, small quantities of pyro solution may be added in order to gain opacity more quickly. PYRO-SODA DEVELOPMENT. When sodium carbonate is used as the alkali in place of ammonia the developer acts somewhat more slowly and is less liable to produce fog, especially with very rapid plates, and there is very little tendency to produce green fog. On the other hand, variations are not so easily made in the composition of the developer. Some people find the absence of the smell of ammonia a decided advantage. Stock Pyro Solution. The same as for Pyro-Ammonia. Dilute Pyro Solution.2 Stock pyro-solution 1 oz. or 10 parts Water 10 oz. or 100 parts Soda Solution. Sodium carbonate, crystallised. 1 oz. or 10 parts Sodium Sulphite 1 oz. or 10 parts Potassium bromide 10 grains or 0.23 part Water to make up to3 10 oz. or 100 parts No more of the dilute pyro solution should be made up than is likely to be used during the same day, but it will keep well enough for a day or two. The sodium sulphite and carbonate are dissolved, with the aid of heat, in about 8 oz. (80 parts) of water, the bromide added, and the liquid when cold made up to 10 oz. by adding water. For use mix equal parts of dilute pyro solution and soda solution and pour over the plate. If the exposure has been correct the image will begin to appear in about a minute, and development is then allowed to go on with occasional rocking of the dish, until the negative is sufficiently opaque. 32 33 34 [2] [3] If the plate behaves as if it were under-exposed, at once dilute the developer with an equal bulk of water and pour it back over the plate. If the high-lights continue to increase in opacity, but the rest of the image does not appear, add some more of the soda solution with or without some more water. Should parts of the plate still remain blank, apply some of the soda solution to them with the aid of a brush as described under pyro-ammonia (page 32). If the rapid appearance of the image indicates that the plate is over-exposed, at once pour off the developer into a measure or mixing glass and rinse the plate well with water. Add to the developer a small quantity of potassium bromide solution (1 in 10 of water) which should be kept at hand for this purpose. A small quantity of pyro stock solution may also be added. The developer is then poured over the plate again. When the over-exposure seems to have been considerable, the amount of potassium bromide added may amount to 4 grains (or 40 minims of the 1 in 10 solution) per ounce of the developer, but this proportion should not be exceeded; even small quantities of bromide in the pyro-soda developer have a marked influence in retarding development. When there is reason to suspect over-exposure, not more than half the soda solution should be added at the beginning of development, and the rest may be added or not, as the case may require. DEVELOPMENT WITH ORTOL. Ortol Solution. Ortol 130 grains or 1.5 parts Potassium metabisulphite4 65 grains or 0.75 part Water to make up to 20 ounces or 100 parts Soda Solution. The same as for pyro-soda. See foot-note to page 30. Mix equal parts of ortol solution and soda solution. This developer behaves in much the same way as pyro-soda and gives very similar results. It has the advantage, however, that it does not stain the fingers, and has practically no tendency to produce either fog or stain on the plates. Moreover the same quantity of solution can be used for several plates; when the action becomes perceptibly slower or weaker, part of the old solution is poured away and an equal quantity of freshly mixed ortol and soda solutions is added. The chief differences to be observed are (1) that the different parts of the image follow one another more rapidly than with pyro-soda, even though the plate may have been correctly exposed, and (2) the colour of the reduced silver is somewhat bluer than with pyro-soda, and therefore in order to obtain the same degree of printing opacity, as distinct from visual opacity, development must be carried a little further. Apart from these differences, what has been said of pyro-soda holds good for ortol soda and need not be repeated. DEVELOPMENT WITH HYDROQUINONE (QUINOL). Quinol Solution. Hydroquinone 90 grains or 2 parts Sodium sulphite 1 oz. or 10 parts Water to make up to 10 oz. or 100 parts Alkali Solution. Potassium carbonate (dry) 1 oz. or 10 parts Potassium bromide 20 grains or 0.46 parts Water to make up to 10 oz. or 100 parts Mix two parts of hydroquinone solution with one part of alkali solution and one part of water, or, if a more energetic developer is wanted, mix equal volumes of the hydroquinone and alkali solutions. Hydroquinone is not an advantageous developer for general purposes, but it is useful when negatives are required showing strong contrast between the highest lights and the deepest shadows, and especially when it is important that there should be no deposit at all in the deepest shadows. This is the case, for example, when copying line engravings, pen and ink drawings and similar subjects. DEVELOPMENT WITH FERROUS OXALATE. 35 [4] 36 This method of development also is not well adapted for general work, but it is invaluable for certain purposes. The reduced silver has a pure grey-black colour and there is exceedingly little tendency to produce fog of any kind. On the other hand, the developer admits of little modification in its composition and therefore the exposure must be fairly correct. It is also important to avoid contamination with even minute quantities of hypo, since this substance very readily causes stains. Ferrous Sulphate Solution. Ferrous sulphate ½ oz. or 25 parts Sulphuric acid Small quantity Water to make up to 10 oz. or 100 parts About three-quarters of the total quantity of water is mixed with a small quantity (not more than 50 minims per 10 ozs., or one part per 100) of sulphuric acid, and the ferrous sulphate (proto-sulphate of iron) which must be in clear pale green crystals without any yellowish incrustation, is dissolved in it...