40 QUEEN'S QUARTERLY. 



tinction to the crude ground logs composing the mechanically pre- 

 pared pulp. The chemical liquid used in making chemical pulp is 

 usually either a mixture of sulphurous acid and bisulphite of hme, 

 or a solution of caustic soda. The treatment with tlicse liquids con- 

 stitutes the sulphite and soda processes respectively. For the manu- 

 facture of the cheaper grades of paper, including newspapers, a 

 mixture of mechanical and chemical pulps is used. The proportion 

 in the mixture varies greatly according to the quality of the paper, 

 fixty-five to seventy-five per cent, of mechanical pulp being an 

 average amount for newspapers. For the finer grades of paper 

 either sulphite pulp or the cellulose from rags is used, the latter mak- 

 ing somewhat the better paper, since the cellulose from wood is 

 •liable to decay in time, while that from rags is practically not af- 

 fected by the conditions causing decay. 



In addition to the cellulose industries taking advantage of its 

 inertness toward deteriorating agents, we have also a large number 

 based on the chemical activity of cellulose, for it proves to be a 

 very active substance chemically toward certain reagents. Strong 

 caustic soda solution acts upon cellulose to produce an effect known 

 a« " mercerisation," after the inventor of the process, Mercer. When 

 cotton is immersed in this solution in the cold it shrinks and becomes 

 silky in appearance, and assumes great activity toward dye stuffs. 

 This industry has assumed large proportions, producing the well- 

 known silky, lustrous " mercerised " fabrics. 



A large number of commercial products are obtained by the 

 action of nitric acid upon cellulose. Perhaps the most important of 

 these is gun cotton, which is used as a high explosive for blasting, 

 for torpedoes and mihtary mines and bombs. When mixed with 

 another explosive it forms the basis of " blasting gelatine," " smoke- 

 less powders," etc. In the manufacture of gun cotton the cellulose 

 of cotton waste is used for the most part. This cotton waste is 

 sorted over at first to remove the larger part of the common impuri- 

 ties; then it is shredded by a suitable machine, after which it is 

 washed, dried at an elevated temperature, cooled, and " nitrated." 

 The nitrating process consists in dipping the cotton into a mixture 

 of strong nitric and sulphuric acids in the proportion of one to three. 

 During this process the cellulose molecule takes up nitric acid radi- 

 cles to form the hexa-nitrate, and liberates water which is taken up 

 by the sulphuric acid. This " nitrated " cotton is now put into cen- 

 trifugal machines and freed from the greater part of the adhering 



