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absolute fac-similes of the drawings of the old masters ; 

 these pictures are as permanent as carbon or chalks can 

 make them. But each of these direct proofs, whether pro- 

 duced in silver or in pigments, requires to be taken separately, 

 and is therefore the work of time and labour which render 

 it too expensive for commercial reproductions. The 

 question therefore arises can we not employ the negative, 

 or positive taken from it, as a sort of mould or type, and 

 print off from it pictures in bulk, mechanically, in a printing 

 or lithographic press, like a wood engraving or lithograph ? 

 This is done, and nearly thirty different processes are em- 

 ployed for the purpose — Woodbury type, Stannotype, Helio- 

 type, Photo-lithography, Heliogravure, &c. A gelatine film, 

 carrying its developed and fixed image, is rolled with great 

 pressure into a soft metal plate, a cast is taken from it by 

 fusible metal, or electrotype, which thus becomes a sort of 

 type or mould from which a picture is taken in a press ; 

 the glass plate itself sometimes being taken as the foundation 

 of the die ; or a print is taken from a negative in greasy ink 

 and laid down on an ordinary lithographic stone or zinc 

 plate. Perhaps the most elegant of all these processes is the 

 most recent one of Obernetter, which he entitles Licht 

 Kupferdrucht. He transforms a dia-positive image on gelatine 

 bromide into chloride of silver, strips the film from the glass, 

 and places it on a copper-plate. Under the influence of an 

 electric current the chloride of silver is decomposed, the 

 chlorine uniting with the copper, and etching the plate to 

 a greater or less depth according to the thickness of the 

 deposit of chloride, the result being a grained intaglio plate 

 capable of giving the most delicately graduated impressions. 

 It is believed Photogravure will sooner or later entirely sup- 

 plant engraving by hand. 



The applications of photography are innumerable. The 

 artist recognises its value in reproducing Form, and saving 

 him much time in copying details from nature. For the 

 delineation of architecture, and fabrics of all kinds, it is un- 

 rivalled. Rock hewn inscriptions hitherto undecipherable 



