36 JOURNAL OF THE [April^ 



process. These are again subdivided into "sulphite," "soda 

 pulps," etc. By the " mechanical" or ground-wood method any 

 suitable wood is taken, usually, on account of cheapness, the edg- 

 ings, slabs from sawmills, small cordwood, and other waste stock. 

 In the " Voelter " process, which is German, the defiberer, or 

 mill, consists of a coarse cylindrical stone revolving rapidly,, 

 against which the pieces of wood are held by springs. The water 

 which flows through assists in reducing the fibre so finely that the 

 subsequent chemical treatment is simple. The "mechanical^' 

 processes, however, breakup the fibres into short particles, thereby 

 reducing the strength of the pulp and permitting less of this pulp 

 to be mixed with linen or cotton, on account of the consequently- 

 greater friability of this woody matter. 



Among the various " chemical " wood-pulp processes is one in 

 which the wood is not disintegrated, as by the "mechanical " or 

 ground-wood methods, but convenient-sized pieces are placed in 

 a steam-tight vessel and boiled with about twenty per cent of strong 

 caustic soda under a pressure of ten to fourteen atmospheres. 

 In another, by the popular " Mitscherlich " patent method, bisul- 

 phite of lime is used instead of soda ; and the best wood pulps, 

 are prepared by the several "sulphite " processes. 



I show you here several examples of these methods in sheets 

 of dried pulp, and finished papers, Nos. 12 to 17, with the color 

 action of various reagents upon them, which were treated by Prof^ 

 Stillman, and which I will explain after I shall have finished this 

 paper. The mounted slides of the corresponding numbers are on 

 the stands for your inspection. 



Now, as if the several methods of paper-making, as briefly de- 

 scribed, were not sufficiently destructive, there is still another curi- 

 ous mode — that is, the converting of cane wood into pulp. By 

 this, the " Lyman " process, the disintegrated cane is placed in 

 strong iron cylinders, called " guns "; these are about twenty-two 

 feet long and twelve inches internal diameter, and are laid on 

 heavy frames. The heads are fastened on both ends, and steam is 

 admitted until a pressure of one hundred and eighty pounds to the 

 square inch is reached. This pressure is maintained for about 

 twelve minutes, when, by pulling a trigger, the covers are suddenly 

 released, and the steam, propelling the mass of disintegrated wood 

 before it, rushes out with an explosion equal to that of a large 



