MICROSCOPY OF PAPER. 97 



stumps, and leather-cuttings have been used experimen- 

 tally for this purpose. Cotton and linen rags still fur- 

 nish the best grade of paper. The manufacture of 

 Manila paper is an important industry. Straw and 

 wood-pulp, however, furnish by far the largest yield of 

 coarse paper and cardboard. The relative importance of 

 the different materials is indicated by the following table 

 from the United- States Census: 



Paper-stock Manufactured in the U. S. in igoo. 



Wood, cords 1,986,310 



Wood-fibre, tons 644,006 



Straw, tons 367,305 



Old paper, tons 356,193 



Rags, tons 234,514 



Manila, tons 99)3°! 



3. The Microscopic Examination of Paper. — Before 

 examining a sample of paper under the microscope, it 

 should be torn into small bits and boiled in a one-percent 

 solution of caustic soda. The wet pulp produced is 

 washed on a fine sieve and broken up by shaking in water. 



The identification of paper fibres is by no means an 

 easy task, and requires careful study and comparison 

 with known substances. The student will be much 

 aided by an admirable monograph prepared by Professor 

 W. R. Whitney and Mr. A. G. Woodman, and pub- 

 lished in the Technology Quarterly for September, 1902. 

 The authors suggest the following points to be noted in 

 the systematic study of each specimen: size of cells, 

 shape, length, width as compared to length, shape of 

 the ends, presence of knots or joints, whether the major- 



