SCIENCE IN THE INDUSTRIAL WORLD 



wood-engraving, and except for certain ultra-artistic 

 and commercial purposes, wood-engraving has become 

 a thing of the past. The skilful wood-engraver of 

 the older generation has been obliged to seek other 

 means of earning a livelihood, although one field is still 

 open to him to a limited extent . This is the ' ' retouching, ' ' 

 or engraving, of the half-tone plate itself. It is found in 

 practice that for very fine printing the half-tone plate 

 can be greatly improved by engraving certain portions 

 of it with a tool, just as in the case of the wood block. 

 Good half-tone printing must be done on paper specially 

 prepared with a surface to get the desired color- values 

 in printing from the ordinary acid-etched plate. To 

 facilitate this printing, and to get the best results, there- 

 fore, the plate is sometimes "tooled" in places, the tool- 

 ing of such blocks having now become the regular 

 occupation of many former skilful wood-engravers. 

 In the actual process of printing, the etched plates 

 themselves are usually not used, duplicates of them 

 made by "electrotyping" being generally employed, 

 the original engraved plate being kept in reserve. This 

 electrotyping-process is a simple one, it being possible 

 to make as many duplicates as desired without injury 

 to the original plate. To make such electrotypes an 

 impression of the engraved plate is taken by pressing it 

 firmly into wax or some other similar medium. The 

 result is an exact cast of the engraving in the wax. 

 This cast is then placed in an electric bath containing 

 a solution of copper, from which the copper is deposited 

 upon the surface of the wax as a thin film of metal, by 

 the action of the electric current. This film of metal, 



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