Eder - History of Photography
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Eder - History of Photography
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[this text, describing the evolution of emulsion technology in the early years is extracted from the 'History of Photography' by Josef Maria Eder, fourth edition (1932), translation by Edward Epstean] GELATIN SILVER BROMIDE Poitevin's experiments (1850) to utilise gelatine as a binding agent for silver salts in the negative process were not wholly successful. Years passed before the idea, proposed by Gaudin in 1853, of producing emulsions with different binding agents, among others with gelatine, was realised. First it had to be learned that silver bromide (not silver iodide) must form the principal part of such emulsions and, furthermore, that the great light-sensitivity of silver bromide becomes effective only by chemical processes of development, for instance, with alkaline pyrogallol. Only when this was known did the use of gelatine (in place of collodion) as a colloid medium in the emulsification of silver bromide meet with complete success. But this vital perception was gained only after many experiments had failed. The Englishman W. H. Harrison published (Brit. Jour. Phot., January 17, 1868), in a short article entitled "The Philosophy of Dry Plates," an account of his half successful experiments with silver bromoiodide (with use of cadmium iodide and cadmium bromide), which he emulsified in a very weak gelatine solution. He coated plates with this emulsion, which he dried, exposed, and developed with pyrogallol. He remarked that the image appeared quickly and was of great intensity, but it was useless, owing to the rough and uneven surface of the film. He attempted to improve his emulsion by increasing the gelatine content, but then failed to obtain an image, proof that his experimentation was faulty. Apparently discouraged, he discontinued further trials with gelatine emulsion after the publication of his failure. In these circumstances he can hardly claim consideration as a pioneer, still less the inventor of gelatine silver bromide emulsions. W. Jerome Harrison mentions, With great accuracy, in his History of Photography (1888, p. 59) these unsuccessful fledgling experiments by W. H. Harrison with gelatine silver bromo-iodide. He can be called, therefore, only an experimenter who stopped after his initial attempt. The experiments of W. H. Harrison so discouraged all other photographic experimenters that for the five years following no one took up the use of gelatine as a binding agent for silver bromide; then Dr. R. L. Maddox independently succeeded in obtaining the first satisfactory images on gelatine silver bromide, which resulted in further progress. This English amateur photographer must be recognized as the inventor of the first serviceable gelatine silver bromide emulsion. Richard L. Maddox (1816-1902) studied medicine in England, followed his profession for several years in Constantinople, and married there in 1849. In 1875 he practiced in Ajaccio (Corsica) and in Bordighera (Italy), and later he returned to England. He devoted himself to photography as early as the fifties and received medals for his microphotographs in 1853 from the Photographic Society of London and in 1865 at the Dublin International Exhibition. While practicing medicine in England, Maddox worked diligently as an amateur photographer. He worked a great deal with albumen films on glass plates, Niepceotypy (Brit. Jour. Phot., VIII, 386); also Kreutzer's Zeitschr. Phot., 1862, V, 58). The editor of the British Journal of Photography was his friend, and he wrote other articles on photographic subjects for this periodical. His most important contribution, however, was the successful experiment with gelatine silver bromide emulsion. On September 8, 1871, Maddox sent the first notice on the preparation of gelatine silver bromide emulsion to the British Journal of Photography, under the title "An experiment with Gelatine-Bromide," and at the same time handed to Taylor, the editor of the Journal, some negatives of landscapes, views and so forth produced by the new process, representing the first successful photographs made with gelatine silver bromide dry plates. Dr. Maddox, in the course of his experiments, was influenced by the Niepceotype process and the wet collodion process, to which he had become accustomed in his younger years, and so started with the physical development (nitrate of silver and pyrogallol) of his gelatine silver bromide plates, thus permitting the silver nitrate to predominate. His modesty caused him to use the expression that he "did not assume to have proposed something new," when he replaced collodion by another binding agent, namely, gelatine, though in fact it introduced a new epoch in photography. He found that the suitable, relatively great concentration of the gelatine solution, which produced smooth films on glass as well as on paper, did no injury to the silver bromide layer in drying. It is very characteristic in the evaluation of this scientist, as he himself stated, that his investigations were by no means concluded, but that he made them public to point the way, as he did in a most admirable manner, and that they ought to be followed by the further elaboration of the gelatine emulsion process. He advised the study of the proportion of bromide to silver nitrate, of the kinds of soluble bromide which could replace the cadmium bromide which he had used, and he recommended also the study of the kind of developer. It is therefore established without doubt that Maddox invented and documented with good proofs, photography with gelatine silver bromide on glass as applied to negative and positive processes, as well as gelatine silver bromide papers in their initial stages. He states at the end of his communication to the British Journal of Photography, 1871: "as far as may be judged at present, the process seems worthy of further and carefully carried out experiments; if found advantageous, progress in photography will be promoted by it." Certainly he did not realize that the bromide should predominate when mixed with silver nitrate and that it was necessary to wash the emulsion in order to obtain more sensitive and more permanent silver bromide plates, a fact which was published only in 1873 by Johnston. The famous negatives sent by Maddox in 1871 to Taylor for his examination were later sent to the present author in the eighties. They were small, delicate, completely detailed brown negatives. Later, in 1900, I received from Maddox a portrait made about that time which is reproduced in the 1932 German edition of the History (p. 591). Dr. Maddox derived no pecuniary returns from his invention and passed his last years in anything but easy circumstances. In 1892 the photographers in England, France, Germany, and America and amateurs subscribed for him a sum of over five hundred pounds. In recognition of the value of his work, he earned the grateful appreciation of his professional colleagues, which was expressed in particular in the presentation of the "Progress Medal" of the Royal Photographic Society in 1901. Dr. Maddox died May 11, 1902, at Southampton, in his eighty-sixth year. It was not until two years later that Maddox's invention was taken up again and improved by others. The Englishman J. Burgess, in July, 1873, offered for sale in London the first gelatine emulsion; it was advertised in the British Journal of Photography (July 18, 1873). Burgess never disclosed his formula for this emulsion, but he undoubtedly used the soluble bromide in excess in preparing the emulsion, since he used an alkaline pyro developer. To him is due the merit of having been the first actually to produce gelatine emulsions in a practical and suitable quality for the trade. This emulsion was, of course, hardly as sensitive as a wet collodion plate, but even this was a great deal at that time. Burgess, however, achieved no commercial success, and the emulsion itself gradually dropped out of the market. J. King, on November 14, 1873, gave a more detailed description of the gelatine emulsion process (Brit. Jour. Phot., 1873, p. 542, and 1874, p. 294; Phot. Korr., 1874, p. 125) , and he introduced the washing out of the soluble salts from the gelatine emulsion. In the same issue of the British Journal of Photography J. Johnston recommended the use of soluble bromide in excess in the emulsion mixture and the washing of the gelatine emulsion. This improvement, that the bromide must be in excess of the silver nitrate, was recognized later as highly important and adopted as a rule for the preparation of gelatine emulsions. As early as 1873 an anonymous writer, who only signed himself "Contributor," in the British Journal of Photography (1873, P. 73), reported that a gelatine silver bromide emulsion could be prepared by dissolving precipitated and washed silver oxide or silver carbonate in ammonia and mixing it with a gelatine solution containing ammonium bromide, but no attention was paid to this vague remark about the use of ammonia. Richard Kennett, an amateur photographer in London, on November 20, 1873, took out an English patent (No. 3782) onthe preparation of stable "sensitive pellicles" (foils) of dried gelatine silver bromide, which were commercially used for a short time. After being softened in water and melted, this dried gelatine silver bromide served for coating glass plates (Brit. Jour. Phot., 1874, P. 291). He also sold ready-made gelatine silver bromide plates on glass in 1874 on a small scale for special orders; but they contained silver bromide of poor sensitivity. In 1873 W. B. Bolton made public his method, which consisted in emulsifying the silver bromide at first with very small amounts of gelatine and later adding more gelatine, a procedure which was subsequently recognized as especially important. In 1874 Peter Mawdsley mentioned in the Year-Book of Photography (pp. 115 - 116 of that year) the applicability of gelatine silver bromide paper, with development for the production of negative and positive prints, and founded the Liverpool Dry-Plate and Photographic Printing Company. It was the first establishment to produce gelatine dry plates and photographic papers in fairly large quantities for commercial use; but the business did not meet with success. J. Johnston described, in 1877, the use of ammonia for ripening gelatine silver bromide emulsions (Brit. Jour. Phot. Almanac, 1877, p. 95), a process which later was investigated more closely and perfected by Monckhoven. In the middle seventies gelatine silver bromide plates, which at that time were not very rapid, equaling in sensitivity only a wet collodion plate, were used in England experimentally for landscapes and here and there by itinerant photographers for portraits. In 1877 the world's attention was directed to dry plates by Pope Leo XIII. One of the first practical accomplishments of the gelatine silver bromide photography was the taking of a photograph of Pope Leo and his entourage in the Vatican garden at Rome on such a plate, with an exposure of one second. The picture was so satisfactory to the Holy Father that he paid it the distinction of expressing his pleasure in the following Latin poem, which he sent to Princess Isabella of Bavaria.' It reads: ARS PHOTOGRAPHICA Expressa solis speculo O mira virtus ingenii! It may be translated as follows: THE ART OF PHOTOGRAPHY Breathed on by the mirror of the sun, Oh marvelous power of the mind, In the meantime the chemical processes involved in the production of gelatine silver bromide emulsions and the means for increasing their sensitivity were studied more closely. As a fundamental observation on the possibility of increasing the sensitivity of gelatine silver bromide, Charles Bennet published, on March 29, 1878, in his article "A Sensitive Process," in the British Journal of Photography (1878, p. 146; 1879, P. 133; Phot. Jour., 1879, p. 68; Phot. Korr., 1878, P. 21, and 1879, p. 86) that gelatine silver bromide greatly gains in sensitivity when it is prepared with an excess of potassium bromide and heated for a long time (five to ten days) at 32° C. Certainly the gelatine underwent a partial change, or it fermented and lost its firmness, but it was improved, according to the procedure, earlier demonstrated by Bolton, of reserving a part of the gelatine and adding fresh gelatine at the end of the "ripening process of the silver bromide." Thus a method was provided for the commercial production of dry plates, although the sensitiveness of the first examples offered for sale was still far behind our modern rapid plates. The road was opened to portrait photography and also to landscape and instantaneous photography. This ripening by heat was subsequently varied, by permitting the action to take several hours at 60° to 80° C. or a half hour at near the boiling point, but the principle remained the same. It was not easy to prepare gelatine silver bromide emulsion in the primitive darkroom laboratories of the professional photographer, equipped as they were at the time for the still-prevailing wet collodion process, and every effort was exerted to produce a large number of dry plates on a commercial scale, keep them in stock, and introduce them on the market ready for use. This brought about the commercial manufacture of sensitive dry plates, which originated in England, as did the entire gelatine silver bromide process. The firm of Wratten and Wainwright put on the market in London in April, 1878, gelatine silver bromide plates of greater sensitvity; this firm did an extensive export business to the continent, and their plates were the first to be used in Vienna, through the agency of the Vienna Photographic Society under the presidency of Dr. E. Hornig, and later in Berlin. The "Liverpool Dry-Plate Co." (Peter Mawdsley) produced in the same year plates of even greater sensitivity, which they called "Bennet plates" and sold at three shillings a dozen (size about 3 1/4 X 4 3/8 inches). In 1879 the English firm of Mawson and Swan entered the field with gelatine silver bromide plates (Sir Joseph W. Swan was formerly a manufacturer of pigment papers). The firm was the first to manufacture, in addition to portrait and landscape plates, "photomechanical plates" for the reproduction processes and to prescribe their development with hydroquinone and caustic potash (about 1890), which is still used today. In 1879 the Belgian chemist and photographer Dr. Van Monckhoven devoted himself to the development of the dry-plate manufacture. Van Monckhoven, in August, 1879," stated that the increase in sensitivity of the silver bromide emulsion under continued digestion was connected with molecular changes. He cited on this occasion the earlier statement of Stas (1874) on the various modifications of silver bromide and made the far-reaching discovery that the ripening of silver bromide was greatly accelerated by ammonia. Supplementing this, Monckhoven published in the Photographisches Archiv (1879) an ingenious emulsion process which did away with the washing of the emulsion. The silver was precipitated as carbonate of silver, washed and mixed with a gelatine solution and converted by the aid of hydrobromic acid into silver bromide. This process, though practical, was not generally adopted, and Monckhoven himself emulsified later in the usual manner with excess of potassium bromide, but ripened the emulsion with ammonia, in order to obtain a greater sensitivity, and afterwards washed as was then the general custom. Further details of the method he used are not known, because he kept it secret. He and his sister-in-law produced the gelatine silver bromide emulsions for the trade in his laboratory at Ghent. Monckhoven prepared only the emulsion and sold his product to two plate factories, namely, Bernaert, in Ghent, and Palmer Descamps in Courtrai, for use in coating the plates. He used in the early eighties 120 kg. (about 264.6 lbs.) of silver nitrate monthly, which he bought in Frankfurt a. M. Bernaert coated daily 1,300 plates (on Belgian glass); some of these plates found daily use, about 1880, in the portrait studio of the court photographer, Jos. Lowy, of Vienna. It was there that the author familiarized himself with these plates and found their sensitivity about 20° to 30° on the Warnerke sensitometer (which is equal to 8°-10° on the Scheiner). These Monckhoven-Bernaert plates became great favorites, owing to their clearness, fine rendering of the middle tones, and brilliancy, but the more sensitive English product replaced them later. Dr. Desire Charles Emanuel van Monckhoven (1834-1882) was one of the most versatile and zealous representatives of scientific and applied photography in the latter half of the last century. He came from the Flemish race and spoke German fluently, although his daily conversation was carried on in French. He studied chemistry, did not engage in a business or profession, lived at Ghent, and devoted himself early in life to photographic studies. In his eighteenth year he published his Traite general de photographie, of which seven editions were published and which was translated into French, German, Italian, and Russian. His other well-known publication was Traite populaire de photographie sur collodion (Paris, 1862). Of importance were his introduction of the dialytic enlarger and an improvement of Woodward's solar camera for enlarging, in 1864, as well as his appliances for the improvement of artificial illumination which he made known in 1869. He spent also a great deal of time in the study of photographic optics. His Photographische Optik was published at Vienna, in 1866, and an English translation, in 1867. He erected in Belgium an establishment for the manufacture of pigment papers, which contributed greatly to the spread of this process. In 1867 he moved to Vienna and aided the portrait photographer Rabending (inventor of negative retouching) in establishing an imposing studio, which excited great curiosity at the time on account of its peculiar constrli ction (large broad front light, with small side light), which, while it realized all expectations as far as optical considerations were concerned, permitting short exposures, did not fully meet artistic requirements. Although he was quite happy in the gay Viennese life, he returned to Ghent in the autumn Of 1870. The medal bestowed upon him by the Vienna Photographic Society in 1871 had to be sent to him there. In 1879 he erected at Ghent a completely equipped laboratory, in which he carried on later his famous experiments in the ripening of gelatine silver bromide and so forth. Instruction sur le procede au gelatino-bromure d'argent (1879) and Du gelatino-bromure d'argent (i88o) appeared at this time. We have already reported above on the emulsion factory established by him. In this laboratory, as a hobby, he made spectral analyses for the investigation of the sensitivity of plates, photographed the speetrum of hydrogen in special vacuum tubes, which had to be used longitudinally and were named after him, occupied himself a great deal with astronomy, and had an observatory in his own house at the Rue de I'Hopital in Ghent, which was purchased by the government after his death. The ammoniacal ripening method of Monckhoven was further developed by the author, whose investigations in 1880 resulted in the method of ammonlacal silver oxide and its introduction to emulsion practice. The author also made public in the same year the favorable influence of ammonia and ammonium carbonate on the ripening of emulsion in the cold. The ammoniacal method is used at present for different kinds of emulsions. For extra rapid emulsion, the neutral boiled emulsion, with a very small gelatine content, became of great importance during the process of ripening. It consisted in treating the silver bromide mixture with very weak gelatine solutions, then allowing it to ripen for half an hour at about 90° C., and only then adding the larger amount, left over, of the gelatine solution. The proportion of bromide to silver nitrate is important, and only a small excess of soluble bromide occurs in this process. The impetus to this improved method was given by the investigations of William de Wiveslie Abney, Burton, and others (Handbuch, 1927, ll (1), by Luppo-Cramer, and 11(2) , by Eder). Soon the number of factories, at first limited, increased in all countries, and as early as the eighteen-eighties highly efficient dry-plate factories sprang up which developed into an industry in which millions were invested. At this time (about 1880) wet collodion plates disappeared almost completely from the portrait and landscape studios and were used only in photomechanical establishments. We mention some of the earliest technical literature on gelatine silver bromide: Abney, Emulsion Processes in Photography (London, 1878); Abney, The Practical Working of the Gelatine Emulsion Process (London, 1880); Burgess, The Argentic Gelatino-Bromide Worker's Guide (Greenwich, 1880); Chardon, Photographie par emulsion sensible; bromure d'argent et gelatine (Paris, 1880); and Monckhoven, Instruction sur le procede au gelatino-bromure d'argent (1879). The first German textbook on the preparation of gelatine silver bromide emulsions based on original investigations appeared in January, 1881, written by the author, Theorie und Praxis der Pbotographie mit Bromsilbergelatine. The author's experiments for the preparation of ammoniacal gelatine silver bromide emulsions were connected with Monckhoven's studies (addition of ammonia to the mixed emulsion). He collaborated at that time with Captain Giuseppe Pizzighelli, in Vienna, began the tests in 1880 for the preparation of emulsions with the use of ammoniacal silver nitrate, investigated accurately its modes of use, unknown at that time, with regard to the proper proportions of the mixture and its temperature, and summarized the detailed results in his dissertation "Beitrage zur Photochemie des Bromsilbers (Sitzungberichte, Akadem. d. Wissensch., Wien, April 8, 1880, LXXXI, 679, also Phot. Korr., June, 1880, p. 144), and in his monograph mentioned above. In the same year appeared an enlarged English edition of that book: Modern Dry Plates; or, Emulsion Photography, ed. by H. B. Pritchard (London, 1881), and later a French edition (Paris, 1883 ). These directions for the work with ammoniacal silver nitrate, through the mild digestion temperature and the rapid working, produced clear and strong gelatine silver bromide plates and opened the way for the commercial production of emulsions. They were used by almost all the older factories in Germany and Austria, for instance, by Haack, Dr. Heid, Schattera in Vienna, Schleussner in Frankfurt a.M., and others. They harmonized well with the new iron oxalate developer which came into vogue at that time, as well as with the alkaline pyro developers which had replaced the ammoniacal pyro developer. The "hard" brands of gelatine, especially suited for this process, were first successfully produced on advice of the author in 1881 by the gelatine factory of Winterthur, which was directed at that time by Simeons. The industrial development of the manufacture of dry plates had its beginning in England. From April, 1878, a large volume of dry plates were exported by Wratten and Wainwright, London, the Liverpool Dry-Plate Co., Mawson and Swan, and others. In Holland, Wegner and Mottu made dry plates for portraiture in 1877 and 1878 which were sold by Schippang in Berlin from January 1878. Their sensitivity was four times greater than that of the wet collodion plate (Wilh. Dost, Phot. Chronik, 1928, P. 376). In Austria (Vienna) Carl Haack was the first to produce gelatine silver bromide plates and offer them for sale, October, 1879 (Phot. Korr., 1879, P. 193). In Vienna the chemist Dr. Heid started, in 1880, a dry-plate factory; later followed Victor Angerer and Dr. Szekely. Lowy and Plener, in 1884, were the first to employ contrifuged silver bromide from ripe gelatine emulsions, and they were also the first to produce and to employ in Lowy's graphic art and reproduction establishment the orthochromatic gelatine silver bromide emulsions with erythrosin according to the author's directions. Later Schattera started under the direction of Perlmann a dry-plate factory in Vienna, which merged with the factory run by Ferdinand Hrdlicka under the name "Herlango," which joined the dry-plate factory of Professor Alex. Lainer. The manufacture of dry plates in the United States is closely interwoven with the name of George Eastman; Eastman offered his gelatine silver bromide plates for sale in 1880, [as described in detail in Chapter XIV.] In France silver bromide plates were produced very early; the most important firm in this line was that of Lumiere. The manufacture of dry plates was started in 1882 by Antoine Lumiere, at Lyon, with a daily output of sixty dozen plates. The firm later grew considerably, under the co-operation and direction of his sons, Auguste and Louis Lumiere, and achieved a triumph in photochemical practice in 1907 through the invention of autochrome plates. The entire recent development of the dry-plate industry is described by Dr Wentzel the Handbuch (1930, Vol. 111, Part I). DEVELOPER FOR GELATINE SILVER BROMIDES Chemical developers (such as pyrogallol solution) proved at an early stage more advantageous for silver collodion emulsion as well as gelatine silver bromide plates than the physical developers of the old wet collodion process. Herbert Bowyer Berkeley (1851 -1891) was the son of the Reverend. Conyers Berkeley, attended Uppingham College and devoted himself in particular to chemistry, which he combined with his private studies in photography; he wrote many papers for the technical journals. Berkeley later entered the employment of the Platinotype Co. (1879) and remained there until six months before his death. He contributed greatly to the improvement of platinotype and had a large share bringing about its popularity among photographers. He is best known for having introduced sodium sulphite in the pyrogallol developer (1882), which preserved it from oxidation and improved the quality, of the negative. It was not long before Berkeley's discovery was applied to all other developers. Berkeley was an excellent photographer whose work was admired in many exhibitions. He had the courage of his convictions and was a good debater at society meetings, but was often too aggressive to make friends. His health declined in the last years his life, and he went to Algiers, where he died in 1891 (Phot. Jour, February 20, 1891). IRON OXALATE DEVELOPERS Carey Lea experimented in 1877 with various developing substances for iodine bromosilver chloride negative papers and found potassium ferrous oxalate especially effective. He dissolved precipitated ferrous oxalate in a boiling potassium oxalate solution and stated that solutions of ferrous sulphate with potassium oxalate were less to be recommended. Later, in 1880, he suggested various complicated iron developers, which contained, besides oxalate, also phosphates, sulphates, borates, etc. It escaped him that the best results could be obtained wlth the simple potassium iron oxalate developer." The author demonstrated this and introduced the iron oxalate developer by mixing two cold solutions of ferrous sulphate and potassium oxalate. This developer produced brilliant grayish-black negatives which offered great advantage over the yellowish-brown and often foggy pyro-ammonia negatives of that time. The introduction of the author's iron oxalate developer greatly aided the general use of gelatine dry plates, which is particularly emphasized by H. W. Vogel in his report to the Vienna Photographische Notizen (1880, p. I). ORGANIC DEVELOPER SUBSTANCES W. de W. Abney published the alkaline hydroquinone developer for gelatine silver bromide negative making in 1880. In the same year the author and V. Toth, of Vienna, discovered that pyrocatechin was suitable as an alkaline developer for dry plates. On this occasion they gave precise data on the influence of isomerism in the blhydroxyl derivatives of benzol. They observed that the para position in the bivalent phenols, which is present in the hydroquinone, shows a very strong action in the alkaline developer on silver bromide; furthermore, that the position given in the pyrocatechin causes a great developing power, while resorcin (meta position) has no energy as a developer. This rule for the developing strength of phenol derivatives was later found correct also for other derivatives, for instance, paramidophenol. The history of substances for the organic photographic developers is briefly as follows: in 1880 hydroquinone (Abney) and pyrocatechin (Eder and Toth) became known as developers; then followed, in 1884, hydroxylamine (Carl Egli and Arnold Spiller); in 1885 phenylhydrazine (Jacobsen). In 1888 Andresen was granted a patent for use of phenvlendiamine as developer; in 1889 Andresen recognized the adaptability of certain naphthalene derivatives (eikonogen), and in 1891 he announced paramidophenol (rodinal) which is still generally used. To the chemist Dr. M. Andresen, who directed the company for manufacture of aniline in Berlin, we are indebted for numerous progressive steps in the chemistry of developer substances, also for the advance in other photochemical fields and for improvements in the manufacture of dry plates. Dr. Momme Andresen was born October 17, 1857, the son of Andreas Christian Andresen, the owner of an estate on the west Schleswig coast, went to elementary school at Risum, his birthplace, later to the Wilhelm School at Niebiill. He studied natural sciences from 1875 to 1880, principally at the technical college in Dresden and at the universities of Jena and Geneva. Between 1887 and 1911 he was employed as chemist by the company for aniline manufacture in Berlin (Agfa) and as technical and scientific director of the photographic department. Since 1911 his connection with the firm has been that of scientific collaborator. Andresen took part in the successful investigation of the constitution of quinone chloramides (Journal f. prakt. Chemie, XXIII, 167, 435; XXIV, 426; XXVIII, 422), as well as the constitution of safranine (Berlin Ber. 1886, P. 2212). He discovered the napththol-disulpho acid (German patent, No- 45776), which is also called Andresen acid. Andresen recognized the great importance which belongs to the ammonia residue NH2, as an "effective group" among organic developer substances, and he discovered paraphenylendiamine (German patent No. 46495, of January 8, 1888), Eikonogen (No. 50265, October 2, 1889), paramidophenol (rodinal) (No. 60174, January 27, 1891). He investigated the action of light on the diazo combinations of naphthylamine, from which sprang a new diazotype process (Phot. Korr., 1895; Jahrbuch, 1896, p. 260). In 1898 he demonstrated that "permanent direct printing papers" could be produced which possess, owing , to an addition of dyes, the maximum sensitivity in any chosen region of the spectrum from the red end into the blue. He supplemented this with an investigation "Zur Aktinometrie des Sonnenlichtes" (Phot. Korr., September, 1898). Andresen is the author of Das latente Lichtbild, seine Entstebung und Entwicklung (1913). and the Agfa-Photo-Handbuch (1922). He wrote the section "Entwickler-Substanzen," for the 5th and 6th editions of the Handbuch (1930, Vol. 111, Part 2). Very important was the discovery of metol, amidol, and glycin as developers by the chemist Dr. A. Bogisch in the photographic department of the chemical factory of J. Hauff, Feuerbach, near Stuttgart. The metol developer is especially important for the rapid development of instantaneous exposures and is very widely used in a mixture with hydroquinone (metol-hydroquinone). It was introduced into practice about 1893 for both negatives and positives. In 1899 Dr. Luppo-Cramer, who was at that time connected with the chemical factory of Schering, in Berlin, made the observation that a substitution bromo- or chloro-hydroquinone increased the strength of the developer over the hydroquinone in alkaline developer, and he called his product "Adurol." Great merit was achieved by Lumiere brothers and Seyewetz in the photochemical laboratory of their dry-plate factory at Lyon. They introduced "metochinon" (a complex compound of metol and hydroquinone), diamidoresorcin, hydramin (combination of hydroquinone with para-phenylendiamine), and have published many research papers on the theory of developer substances (Handbuch, 1930, VoI. III). UTILIZATION OF TANNING PHOTOGRAPHIC GELATINE SILVER BROMIDE FILMS BY PYROGALLOL DEVELOPERS FOR REPRODUCTION PHOTOGRAPHYf Gelatine silver bromide films present the image as a swelled relief after development with alkaline pyrogallol without sulphite. The author pointed out in 1881, in the English edition of his Modern Dry Plates (p. 124), that this relief could be made sufficiently high so that a mold could be made from the swelled gelatine image and used as photomechanical printing plates (see also Handbuch, 1922, IV (3), 304). Leon Warnerke, a Russian living in England, made in that same year a much more important report on the property of the gelatine film tanned with pyro developer, namely, that only those parts which had not been exposed to light were soluble in warm water, while the exposed parts, tanned by exposure, remained insoluble (Phot. News, 1881; Phot. Mitt., XVIII, 65, 98, 235). These relief images can be produced with fixed, as well as with unfixed, silver bromide paper prints, and they can be transferred in the manner of pigment prints to other surfaces, as described in the sections "Pigmentverfahren," in Handbuch (1926, IV(2), 293, 395), and "Heliogravure," in Handbuch (1922, IV(3), 306). This process was thoroughly elaborated by the ingenious amateur photographer Warnerke and demonstrated by practical proofs. The Royal Photographic Society of London awarded him a prize for the process, but it met with no success commercially. He extended his experiments by introducing the "silver pigment process" for intaglio etching of copper plates, but was no more successful in this than the earlier process. Warnerke's work became more important, however, when the original developing method found practical application through the introduction of pyrocatechin in different forms by Gustav Koppmann ( 1907); all this is exhaustively treated in the Handbuch (1926, IV (2), 294). FIXATION OF GELATINE DRY PLATES Gelatine dry plates were always fixed with "hypo" (sodium thiosulphate). The organic developers, pyrogallol, hydroquinone, and eikonogen sometimes indicated a so-called fogging tendency, which had to be eliminated by immersion in acid-fixing solutions, alum baths, and so forth, in order to obtain clear negatives. The acidulation of fixing baths with acids prevented the rapid decomposition of the fixing salts. In 1889 Professor Alex. Lainer, of Vienna, during his work at the Graphische Lehr- und Versuchsanstalt, found that sulphites could be mixed to a clear solution with fixing baths and that in this manner fixation and removal of the fog were obtained in one manipulation. He published this in the April number of the Phot. Korr. (1889, p. 171). This was quite important in the use of the new developing agents that made their appearance at that time. Alexander Lainer (1858-1923) studied chemistry at the technical college in Vienna, in 1882 taught physics, chemistry, and optics in the photographic department of the government trade school at Salzburg, and was called to the newly founded Graphische Lehr- und Versuchsanstalt, in Vienna, as professor of chemistry and physics (1888-1900). He wrote, in 1889, a textbook of photochemistry, Lehrbuch der photographischen Chemie (1890; 2d ed., 1899); he published Vortrige uber photographische Optik (1890); and Photoxylographie (1894); and wrote on the utilization of the residue of precious metals and numerous articles for photographic periodicals. During the course of his studies on photographic developers he discovered that under certain conditions the action of the developer is accelerated by the addition of potassium iodide (in contrast to potassium bromide), which in the technical literature was designated as the "Lainer effect" and was the starting point of many investigations (Handbuch, 1927, 11 (1), 223, by Luppo-Cramer). He resigned from the institution in 1900 in order to establish his factory for photographic papers and plates, which later became so well known. After his death, in 1923, his son Oscar took over the business and merged it with that of Hrdlicka. It was just at this time that M. Andresen, in Berlin, invented the eikonogen developer which the Agfa Co. brought into the market. This developer tended greatly to the formation of fog, but this was The generally used "acid sulphite solution" of today for the acidulatlon of fixing baths, consisting of sodium bisulphite with excess of sulphurous acid, was introduced by the author in August, 1889 (Phot. Korr., 1889, p. 200; Handbuch, 1930, III (2), 200). REDUCTION OF GELATINE SILVER BROMIDE IMAGES The reduction of both negatives and positives was carried on during the years of the Talbotype and of the collodion process according to various methods, which are described in special chapters of the Handbuch (Vols. 11 and 111). After the publication by the author of the mechanism of the reaction of potassium ferricyanide on silver, in 1876, it was known that ferrocyanide of silver is formed by this procedure. This is soluble in hypo. The reduction by the treatment of silver images with potassium ferricyanide and subsequent fixation is based on this reaction. The English worker E. Howard Farmer was the inventor of this mixed reduction bath, consisting of hypo with the addition of potassium ferricyanide (1883). The reduction occurs in one bath and is therefore more easily controlled. This Farmer's reducer became very important in photochemistry. Reduction with potassium permanganate was invented by Namias [see Chapter XCVI]. The reduction with ammonium persulphate (1898) and also cerisulphate (1900) were by Lumiere and Seyewetz (Handbuch 1903, III, 556, 558). Intensification of gelatine silver bromide images followed methods analogous to those employed with collodion negatives. |
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