SCIENCE IN THE INDUSTRIAL WORLD 



in the paper used, although, of course, there is also a 

 difference in the care used in printing the two publica- 

 tions. 



It is possible to give a high polish to any good grade 

 of paper by super-calendering; and while such a 

 paper resembles the surface of a "coated" paper in 

 general appearance, the coated paper can be detected 

 by a simple test. If the finger is moistened and rubbed 

 for a moment on the surface of any coated paper, the 

 clay will be loosened and adhere to the skin in a thin 

 film of powder. This will not occur with any other kind 

 of paper; and this test can be made with any illustrated 

 magazine, the pages having the illustrations being of 

 coated paper, while the text pages, particularly if there 

 are several together without pictures, are very likely 

 to be of plain paper. 



The clay used for making this coated paper conies 

 from Cornwall, England, and is pure kaolin, or china- 

 clay. This is ground to the fineness of fine flour, mixed 

 with glue and spread on a body-paper, dried, and calen- 

 dered. This coating-process is a special department of 

 paper-making, and many large establishments, where 

 coated paper is manufactured, do not make any of their 

 own body-papers, but obtain them from other manu- 

 facturers. 



The machinery for coating the paper is very simple. 

 It consists essentially of a vat for holding the coating 

 material the "enameling solution" as it is called 

 some rollers for regulating its distribution, sets of brushes 

 for working out lumps and still further regulating the 

 distribution, and automatic carriers for taking the paper 



