September, 1926
INDUSTRIAL -4ND ENGINEERING CHEMISTRY
915
Fifty Years of Photography‘ By C. E. K. Mees EASTMAN KODAKCo., ROCEIESTBR, N. Y.
of motion picture film TRIC T L Y alone exceeds 150,000 speaking, i n miles i n a y e a r . 1876 there was Xearly 5 million no photographic inpounds of cotton are dustry, while today used each year for the motion pictures can manufacture of film, be made by the amaand over 3 tons of teur with as m u c h pure silver bullion are ease and a s little used each week. The knowledge as the ortotal power required dinary s n a p s h o t s . exceeds 20,000 horseThe photographer of’ power, and the confifty years ago manusumption of coal is f a c t u r e d h i s own over 500 tons a day. materials and went> The industry owes f o r t h t o t a k e his its progress largely to p h o t o g r a p h s very t h e e f f o r t s of the much as is shown in c h e m i s t s . This is Figure 2, carrying on Figure 1-Photographic Camp in 1876 Showing Photographer and His Assistant particularly true of his back not only his Carrying Out Their Operations t h e p r o d u c t i o n of c a m e r a but also a portable dark room, which he erected in the field (Figure I ) so film, the preparation of the flexible support being one of that he could prepare the sensitive plates for use, c’xpose them the triumphs of chemical technology. The greater part of while still wet, and develop them before they had time to dry. this flexible support is made by the nitration of cotton, the The process of that date was known as “wet collodion.” nitrocotton being dissolved and spread out to form the thin The photographer coated his glass with a solution of nitro- support. I n addition to the nitrocotton film, which is highly cellulose in ether and alcohol containing iodides soluble in inflammable, a large amount of film is now made from cellulose alcohol, and immersed the coated plate in a tank containing acetate produced by the treatment of cotton with acetic silver nitrate solution, which precipitated silver iodide in anhydride and acetic acid. the film. After exposure, which lasted a second or more in It is onlv in the last few years that much progress has been bright light, the plate was developed immediately with an made in the study acid reducing agent, which precipitated the silver upon the of the fundamental exposed iodide particles, and the remaining iodide was dis- theory of the photosolved in cyanide solution. After a brief washing, the thin g r a p h i c p r o c e s s . film was dried rapidly and the negative was ready for me. This has been partly For printing, the photographer either prepared his own because of the secrecy paper or bought albuminized paper which had been coated which surrounds the with albumin containing chlorides and which he sensitized a c t u a l processes of himself by flowing on a solution of silver nitrate. The supply photographic manuof albuminized paper was the nearest approach to a photo- facture and especially graphic industry which existed in 1876. of emulsion-making, The photographic industry owes its development to the but still more on acintroduction of the gelatin process, in which the sensitive count of the complex salts held in gelatin could be used in a dry state and therefore nature of the chemcould be prepared by a manufacturer and supplied to the i c a l r e a c t i o n s inphotographer ready for use. Wet collodion was thus sup- volved. Only w i t h planted by ready prepared gelatin plates and the albuminized the development of paper by paper coated with an emulsion of silver chloride modern physical and in gelatin, which could be developed in the same way as the colloid chemistry has dry plate. For most purposes the dry plate wac eventually it become possible to replaced by the flexible film. study the factors to At the present time the photographic industry employs which t h e sensisome forty thousand people throughout the world, about tiveness of p h o t o twenty thousand of whom are occupied with the preparation graphic emulsions are of sensitive materials and the remainder with the manu- d u e a n d t o under- Figure 2-The Amateur Photographer of 1876 facture of cameras and the wholesale distribution of the stand the nature of products to the retailer. Photographic manufacture is photographic sensitiveness and the reaction which the photoorganized chiefly in modern factories producing on a large graphic material undergoes on exposure to light. During the scale and using specially designed machinery at every step last five years, however, great progress has been made in this of the process. I n the largest of these factories the output field, and there is reason to hope that before long a clear and 1 Received April 9, 1926. coherent theory of the photographic process will be avail-
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Vol. 18, No. 9
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ahh!. A notable advance has been the discovery by S. E. Rlieppard that the high degree of sensitivoness conferred by emulsification in gelatin as compared with tlie use of collodion is due to the presence in the gelatin of smdl traces of organic sulfur compounds which unite with thc silver bromide and decompose, forming silver sulfide on the surface of the bronride crystals. In one branch of photography the hopes that our predecessors in 1870 might just.ifiahly have entertained have not been realized. I n 1861, Clerk Maxwell laid down the hnsic principles of color photo and in 1909 he discussed Duros du Ilauron published a honk all the processes of color photography which he could foresee at, that time. Fifty years later, we ust acknowledge that,
I
1
I Figure 3-Photographic
Seneifivity Today
while we have been able to realize the proeemes which du Hauron suggested, we have made practically no advance beyond them, and that color photography is still so difficult in operation that there are only a very few workers in the art throughout the entire world; moreover, the processes which we are using do not show any possibility of developing in such a way that colur photography may have the widespread distribution that monochrome photography has attained. It is, indeed, generally considered by workers in photographic science that we shall eventually have to dcvelop some entirely new system of color photograplxy, depending upon principles quite different from those which du Hauron suggested or which have been proposed up to t.lre present day. Of such a system we have at tho present time, however, only a few slight suggestions. The applications of photography a t the present time are extremely wide. Photogaphy is the handmaid and tool of all the sciences. The astronomer, who in 1876 would have a1 observation, today would use spectroscopes of fifty years ago nd textbooks; the modern spectroally. The microscopist is turning to ilie photographic plate as a standard tool, and i t is not unlikely that in the near future the microscopist will expect to photograph what he cannot see and will use the eye chiefly as a finder for the camera. Tlic discovery of the x-ray in 1895 opened a new field of photography which bas g r o m to so vast an extent that a t the present time more films are used for radiography than for portrait photography, and it might almost he said that tlie aver%@ citizen is more likely to have a photograph taken of his stomach than of his face. The radiography of tho teeth is now very common, but probably in a few years radiogrirphie examination will not be a special operation but a routine procedure during dental surgery. The application of aerial photography, developed to such great proportions during the war, to peacetime surveying presents considerable difficulties, nevertheless, a large amount of aerial photography is done in every country, and special
apparatus and material3 have heen developed t o suit the requirements of this work. Perhaps the largest field of applied plrotography is in the preparation of engravings, and liere imtil quite recently the wet collodion process, which was the standard process in 1876, still reigned supreme. Even now by far t,he largest quantity of negatives used for photo-engraving is made on wet collodion plates which tire photographer prepares and develops exactly as he did in 18i6. The rise of the rotary intaglio processes and of photolithography is now threatening the half-tone process and with it the wet collodion negative, a.nd a t the present time large quantities of photographic mat,erial are used in connection with this and other reproduction processes. Although direct color photography has not develoned to anv meat extent,. color renroduction nrocesses hav; become ;e;y important, and coiored prints add to the amenities of our dailv life. the nrocesses used beine Maxwell Lnd du Hauron, mad; of color-sensitizing s has been made in the last thirty otographic material ultra-violet region, which materials are useful has been until it is now common to photograph sible spectrum In the red and even beiotorrraphic practice. while in spectro. scopie work the infia re& 5s far as a u&e length o f one micron, can he photographed wit.hout difficulty (Figtire 3).
FiBvre
4-The Modern Photographer
Amateur
The photographic industry, lrowever, would still be a sinall industry did it not include that extraordinary development-motion pictures. The first rcproduction of movement in the early nineties developed very rapidly until i t is now one of the great industries of the world and almost everybody goes to the "movies"-so that the photographic industry, nonexistent in 1876, is in 1926 dwarfed by its child. It is not impossible that a still greater extension of photography will he found in the application of the principles of motion pictures to amateur photography (Figure 4).
