56 OUR VANISHING FORESTS 



ceedingly interesting, but the writer would advise 

 all those suffering from a supersensitive nose to 

 content themselves with a mere description and 

 keep away from the factory. Commercial methods 

 vary, but all involve cooking wood chips in a strong 

 chemical, repeated washing, and then perhaps 

 evaporation of the liquor to reclaim the valuable 

 acid salts. Newsprint-making usually employs the 

 so-called "sulphite" process, in which various com- 

 pounds of sulphurous acid form the basis. Sulphite 

 pulp makes up over one-half of all the chemical 

 pulp produced in the country. This method works 

 very well for spruce and similar light woods which 

 do not have a very heavy resinous content, but such 

 woods as pine, which furnish a very large percent- 

 age of the pulp for wrapping paper, cardboard and 

 the like, have to be somewhat differently treated. 

 Compounds obtained from sulphuric rather than 

 sulphurous acid are here used, sodium hydroxide 

 and sodium sulphite being the principal digestive 

 agents. The "sulphate" process as distinguished 

 from the "sulphite," at present only accounts for 

 about three per cent, of our total chemical pulp, but 

 has great potential importance for the manufacture 

 of so-called Kraft paper from sawmill and forest 

 waste. An older and somewhat better known 

 process for treating hardwoods and other species 



