The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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use of hyposulphite of soda, however, soon became general, Sir Humphrey Davy having, in 1821, published the action of this salt upon the salts of silver. In 1841 Fox Talbot patented his process called Talbotype or Calotype (q.v.). To the Rev. J. B. Reade is due the credit of first recommending a developer, although Fox Talbot was the first to use a restrainer. Up to this point paper negatives alone were in use; but in 1848 a cousin of the original Niepce, M. Niepce de St. Victor, proposed the use of albumen on glass as a vehicle for the sensitive salts of silver. These plates, however, were very insensitive, and numerous substances, such as starch, gelatine, gum, etc., were proposed; none, however, were successful. In 1851 Le Gray, of Paris, and Scott Archer, of London, proposed the use of collodion, the latter publishing such a complete description of the wet collodion process that but little improvement has ever been effected. A great disadvantage, however, of this process was the necessity of exposing the film whilst wet, necessitating the use of bulky and heavy impedimenta for the landscape photographer, in the shape of dark tent, etc. It was then dis-covered that the application of certain organic substances to the washed film would allow of the plates being used in the dry state. In 1862 Major Russell discovered the use of alkaline pyrogallol as a developer, and his accidental discovery of the restraining power of the soluble bromides gave the first impetus to the manufacture of bromide of silver films, which could be exposed dry. In 1864 Messrs. Sayce and Bolton described the process of making collodion emulsion, which was poured upon glass plates, and then washed to free from inert salts. In 1874 it was discovered that the emulsion might be washed previous to use, and in 1871 Dr. R. L. Maddox published a notice of a gelatine emulsion, and from that, in 1878, Mr. Charles Bennet realised the capabilities of the process and power of increasing the sensitiveness by digestion at high temperatures. Since then the process has been made more rapid, the ammonia process becoming known, rapid films and plates being of every-day occurrence. During the last few years film photography has become quite a standard process. Of the application of photography in everyday life it would be almost impossible to treat; the various mechanical printing methods, the use of photography for supplying pictures for illustrated papers, cata-