After 12 hours the 166 gallons (750 litres) are converted into electrolytic bleach liquor containing 26¾ lbs. of active chlorine (12·15 kilos.).
Beating.—Although the rags are reduced by the breaking engine to a condition of fibrous lint, called “half-stuff,” they are not fit for conversion into paper. They have to be beaten in special machinery until a complete separation of the single fibres has been effected, and this process is rightly regarded by many paper-makers as the most important stage of manufacture.
Fig. 12.—Oettel and Haas' Apparatus for the manufacture of Electrolytic Bleach Liquor.
The beating engine is similar in construction to the breaking engine, but there are certain essential differences in arrangement and manipulation. There is usually no drum-washer; the roll contains a large number of knives which are fixed in clumps or sets of three round the circumference; the lowering of the roll upon the bed-plate is carefully watched and controlled, and the desired effects are only obtained by strict attention to the condition of the pulp during the whole process.
Fig. 13.—The “Hollander” Beating Engine.