The principal methods now in use in England of preparing paper pulp by chemical means are those of Sinclair, Houghton, Lee, Deininger, Ungerer, Thode, and Lahousse, and the special processes of Belgian and Alsatian manufacturers, such as Orioli, Jarosson, and Bushaert,effect such a desirable result.
Many attempts have been made to recover the alkali, and, although as high as eighty-five per cent of the alkali was recovered by Sinclair, others failed altogether or produced very unsatisfactory results, and now the processes of boiling with alkaline solutions have become so much improved, that thence it is drawn off by appropriate cocks.
The disintegrating effect, though not so thorough as that produced by alkalies, is yet sufficient for the purpose.
Sinclair's method is employed in reducing wood, bamboo, straw, thistles, etc. The material partially comminuted is treated with a solution of caustic soda at a temperatur
e handle B, being prevented from falling out while one shaft is substituted for the other by a screw F entering a slot in the pawl.
A drill whose rotatory movement is derived from a ratchet and pawl actuated by a lever.
The movement is usually intermittent, the pawl engaging the teeth only when the lever is pushed in one direction, and slipping over them when drawn backward.
In some, however, a continuous rotary motion is imparted to the drill.
Sinclair's (Fig. 4177) is of this kind.
The spindle A has a ratcheted shoulder F which holds the forked handle E E and disk handle D D in place, and in which the pawl G engages when this handle is worked in one direction.
When the movement is reversed a second spring-pawl on the handle E engages the teeth of the wheel C, which are inclined in a direction opposite to those on the disk F. Pins on this wheel engage the pinion e, which rotates the wheel I; during this movement a spring-bolt J in the d