II. Practical Experiments. 



A series of experiments was next undertaken on 

 a somewhat larger scale to approach a little more 

 closely the conditions which would be met in com- 

 mercial operation. The aim was to prepare the 

 wood in the form of chips of the ordinary pulping 

 size, then to subject the chips to a mild preliminary 

 steaming in dilute alkali to recover the rosin and 

 turpentine, and finally to cook the extracted chips 

 in stronger alkali in the usual way for pulp. The 

 preliminary extraction was studied to determine 

 the conditions for complete solution of the rosin 

 and simultaneous distillation of the turpentine 

 without too serious an attack of the wood itself. 

 The draining of the alkali extract from the chips 

 and the salting out of the rosin soap by subsequent 

 addition of excess caustic soda were carried out 

 with conservation of alkali in mind, as well as 

 high recovery of rosin soap. The second stage of 

 the process the production of pulp from the ex- 

 tracted chips was carried through mainly to note 

 any possible deleterious effect of the preliminary 

 steaming on the quality or yield of the final pulp. 

 The experiments were designed to throw light on 

 the problem of commercial feasibility rather than 

 to establish exact practical data. 



The wood studied was limited to box-face slab 

 material. As no pulp-wood chipper was available, 

 the cleaned slabs were reduced to chips by sawing 

 in short lengths of about one inch and splitting as 

 uniformly as possible. Fine material was elimi- 

 nated and the chips were reduced to an average 

 size of about 1| in. x f in. x 3 /32 in., the thickness 

 ( 3 /32 in.) being the dimension held most rigidly 

 within narrow limits. These chips were consider- 

 ably longer than the smallest commercial size, and, 

 as penetration of wood proceeds most readily along 

 the grain, the conditions for alkali extraction were 

 certainly as severe as industrial practice would 

 necessitate. The chips used in Experiment 6 were 

 prepared from the main supply by reducing the 

 size to approximately 1J in. x J-f in. x Vie in. 

 The main supply of chips was thoroughly mixed 

 and a representative sample obtained for analysis 

 by quartering and subdividing. 



26 



