SCIENTIFIC NOTES. 39 



great extent. Its molecular structure seems to be very complex, so 

 much so, in fact, that chemists have been abk to learn very little 

 regarding it, excepting to determine its constituents, which are hy- 

 drogen, oxygen and carbon, and the proportions of these elements 

 present in the molecule. It may seem strange that so very little is 

 known about the structure and reactions of this, one of the com- 

 monest of substances. However, after one learns something of the 

 difiSculties connected with cellulose research, he ceases to wonder 

 any more. A few facts in regard to the cellulose molecule have, 

 however, been hacked off here and there, and further, every fact 

 won from cellulose has been capable of industrial application. 



The very fact that cellulose is a very inert substance, not easily 

 acted upon by chemical reagents, air, or moisture, leads to a number 

 of very large industries taking advantage of this. Among these, the 

 most important are those of the manufacture of paper, cotton and 

 linen fabrics, thread, twine and rope. First in importance comes 

 paper. The tremendous development in printing has created a de- 

 mand for paper which is enormous. It has been generally under- 

 stood that paper is made from rags. While this is true, there exists 

 not one-thousandth part of the rags that would be necessary to 

 supply the demand for paper. As a result other sources have to be 

 resorted to. The principal of these are esparto grass, straw and 

 wood. Of these wood has become by far the most important source 

 of supply, and the wood pulp forests of Canada have received much 

 attention from the world at large as a source of raw material for 

 paper. 



In the manufacture of paper from wood the first process con- 

 sists in converting the wood into wood pulp. Wood pulp is of 

 two kinds, mechanical and chemical, depending upon the particular 

 method of treatment. Mechanical pulp is made by simply grinding 

 up the logs after they have had their bark removed and have been 

 cut into suitable lengths. This ground or pulpy material is then col- 

 lected and subjected to pressure to get rid of the excess of moisture, 

 and is then ready to be shipped to the paper mill. Chemical pulp is 

 made by a distinctly different process. The logs are cut into chips 

 by a special chipping machine. These chips are then placed in tall 

 cylindrical steel vessels lined with special acid-resisting brick, and 

 then a chemical liquid is run in, after which steam is forced in and 

 the contents boiled for eight or ten hours. This treatment succeeds 

 in dissolving practically all the hard and resinous substances away 

 from the cellulose, leaving a fairly pure form of cellulose, in dis- 



