[1837. PROCEEDINGS OP UNITED STATES NATIONAL MUSEUM. 717 



graph. The process was advertised by Mr. W. J. Linton, in London, in 

 1861. 



Frame 35. — Xos. 170 and 177, from a pamphlet, entitled " Speci- 

 mens of a new process of engraving for surface-printing." Loudon, 

 1861. 



19. THE WAX PROCESS. 



A coating of white wax, prepared according to a secret formula, is 

 spread upon a metal plate. Upon this coating a photograph is made 

 of a drawing in lines, and these are cut through, down to the metal, by 

 suitable instruments. The larger spaces between the lines are built up 

 with wax and an electrotype is made. As the first deposit furnishes 

 the relief-block for printing and not merely a mold, it is evident that 

 the drawing on the plate can be executed on the wax coating without 

 reversing. This process is used principally for map work, diagrams, 

 machine drawings, etc. 



Frame 35.— No. 178, by Jewett & Chandler, formerly of Buffalo. 

 Ko. 179, by Jos. Struthers & Co., New York. 



20. THE GPtAPHOTYPE. 



According to Knight's Encyclopnedia a zinc plate is covered with a 

 chick coating of oxide of zinc, under hydraulic pressure. Upon this 

 the drawing is executed with an ink consisting of a chloride of zinc 

 and a menstruum. Where the ink comes in contact with the coating the 

 latter is hardened by the formation of oxychloride of zinc. The rest 

 of the coating is removed by brushing and rubbing. In one form of 

 the process the adhering material is solidified by immersion in a solu- 

 tion of silicate of soda. Invented by D. C Hitchcock. 



Frame 35. — No. 180, from a pamphlet issued by the Graphotype 

 Company, in New York, in 1861. 



21. CLAY-SURFACE PROCESSES. 



There are several processes, which proceed in the main as follows: A 

 metal plate is covered with a composition of pipe clay, etc., according 

 to a secret formula. In this mass the drawing is executed with hook- 

 shaped tools, down to the surface of the metal, so that the design shows 

 dark upon a white ground. A stereotype (cast in type metal), made 

 directly from such a drawing, furnishes a relief block for the type press. 

 It follows that it is «ot necessary to rev^erse the drawing. The rapidity 

 of these processes makes them useful for quick newspaper work. 



