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 22

BULLETIN

309,

U.

S.

DEPARTMENT OF AGRICULTURE.

Screened pulp from the four cooks was combined into one beater charge, heated to about 40° C, and after being thoroughly mixed with bleach liquor to the equivalent of 21 per cent of its bone-dry weight of commercial bleaching powder, was pumped to a bleach chest When the bleach was practically all consumed and the to exhaust.

Fig. 12.— Semicommercial rotary pulp boiler.

was found to be satisfactory, it was drained and washed free from bleach residues. The bleached stock was then beaten with a medium brush for 2

color of the stock

hours, loaded with 25 per cent of clay, sized with a 0.5 per cent resin

and 2 per cent of alum, and run through a Jordan refiner and then to a 30-inch Fourdrinier paper machine speeded to 90 feet per minute. The stock acted very well on the paper machine, giving

size