After washing the half-stuff passes to vats or drainers, and is next brought to the

POTCHING OR POACHING ENGINE,

which in general appearance is similar to the breaking and washing engine, being furnished with a roll carrying paddles (in place of knives) and a drum covered with a finer gauze than that used in the washing engine. At some mills esparto, after boiling, is washed in this engine. A later type consists of a trough having a drum washer but no roll, a centrifugal pump being fitted to circulate the half-stuff, which is here further mixed and brought into a suitable condition for bleaching, a process performed in this engine by means of chloride of lime or some such bleaching agent.

To neutralise the bleach after it has done its work, some antichlor is added, either here or in the beating engine.

The half-stuff is once again passed to chests, vats, or drainers, and then either to the beating engines, or some pulps are passed over sand tables and through strainers as adjuncts to and before being run on to the

PRESSE PÂTE

(Figure 6), which in general details is similar to the paper-making machine after described, but without the drying cylinders, and the thick wet web (in appearance very like a light blanket or thick blotting paper) as it comes off this machine is taken away in trucks and stored ready for use in the beating engines as required, or broken off and dropped once more into a stuff chest, where it is again mixed with water before passing to the beating engine.

CONE BREAKER.

This machine is used for reducing "broke" papers, wood pulp, etc., prior to being fed into the beating engines.

Also esparto, after boiling, may be passed through a breaker, which results in the stuff being thoroughly broken up, so that much of the impurities it contains, such as sand, other grasses, etc., are caught in the sand traps and strainers, on to which it is next run prior to washing; some makers, on the other hand, catch

these impurities after washing. The machine consists of an outer iron casing and revolving inner cone (making about 150 revolutions per minute), both armed with teeth.

KOLLER GANG OR EDGE RUNNERS.

Another and older type of reducing machine is known as the Koller Gang or edge runners, and consists of a cast-iron dish, granite bedstone, and two vertical granite edge runners. We are all of us familiar with a machine of the same type in the common mortar mill.

BEATING ENGINES.

These engines have again a family likeness to the rag engine, being fitted with a midfeather. The roll, however, carries a much larger number of knives, and revolves more rapidly, but there is no drum except in case of compound washing and beating engines. In place of a midfeather another and later type of beating engine is divided horizontally half way up trough, forming an upper and a lower channel. The half-stuff passes through the tunnel and over the top, the roll being fixed in upper part of engine with bed plate beneath. Figure 7 illustrates the exterior of the "Acme" beater, an engine of this type, whilst Figure & clearly indicates the interior, showing the bed plate and roll, the division between the two channels, and the Archimedean screw by which the pulp is raised from the under to the upper channel. In the beating engine the half-stuff, which may have come either from the breaking engine, the potching engine, or the presse pâte, is cleared of bleach, and in turn loading, sizing, and colouring matter are added and worked up with the pulp, the two former for the purpose of producing weight, body, strength, and finish.

To neutralise the bleach some "antichlor," commonly either hyposulphite of soda or hyposulphite of lime, is used. Loading is effected by the addition of china clay, pearl hardening, or some like substance. Sizing (known as engine sizing) is obtained by the introduction of resin soap, to which, for certain papers, starch paste is added, and after the size has been thoroughly mixed with the pulp, to make it fully effective a certain quantity of alum or sulphate of alumina is incorporated. Even pulp having a pure white appearance in the beating engine would have a yellow shade