Experimental and Applied 281 



The processes of treating wood have already been discussed, 

 as they admit of classification on strictly theoretical lines, and 

 afford a useful illustration of the general principles of the 

 relation of the cellulose to the non-cellulose constituents of the 

 compound celluloses. In extending this classification to the 

 wider range of raw materials above indicated, it is necessary to 

 remember the general features of the three groups of compound 

 celluloses, and more particularly the conditions under which 

 they are resolved into cellulose and non-cellulose, observing 

 also that any process of resolution to be available for the 

 purpose in question must be limited in its attack as much as 

 possible to the non-cellulose components. The following may 

 be laid down as a broad principle of economy in such treat- 

 ments : effects required to be produced should be separately 

 accomplished, and obtained by specific reagents. It must be 

 conceded at once that this is an ideal seldom realisable. The 

 treatments of the papermaker are nearly always * overhead' 

 treatments, in which one process and one reagent is employed 

 to work a very complex mixture of chemical decompositions. 

 But because practice tends to stereotype itself on the lines of 

 apparent simplicity, it is not for the chemist to accept this 

 order of things as unassailable. Experience has shown, and is 

 continually showing, that * division of labour ' in reactions is as 

 economical as it is in other branches of work; and it is a 

 particular purpose of this discussion to suggest a careful re- 

 vision of these ' overhead ' treatments, with the view of improv- 

 ing methods wherever possible. 



The pectocelluloses from our present point of view need no 

 discussion. They are easily resolved by alkaline hydrolysis of 

 the simplest kind, i.e. boiling at the ordinary boiling temperature 

 with solutions of the alkalis. The resulting cellulose would be 

 approximately pure and structurally disintegrated, Le. in the 

 condition of ultimate fibres. 



