NEWSPRINT

261

the newsprint stock usually at the Trimbey or other form of proportioner.
Alternatively it may be measured in boxes of suitable capacity, and added to
the beaters.

Alum, either in the form of kibbled 17 to 18 per cent quality, or as 14 to
15 per cent slab alum, is dissolved in tanks having a perforated false bottom
fitted quite near the top. The alum is loaded on to the false bottom, and water

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PIG. no.—TYHCAL CLAY SLUMPING PLANT, SHOVING Two MIXING TANKS FROM WHICH THE SLDMY
HOWS BY GRAVITY, THROUGH A Dnfflcr-DmvEN ROTARY STRAINER, TO THB STORAGE TANK

is run in until the solid alum is just covered. As tlie alum dissolves, tic denser
solution Ms to the bottom of the tank, thus giving some natural circulation
which helps to speed up the dissolving process* Sufficient alum is added to
the tank to give a solution containing 2 to 5 Ik per gallon. A useful check
of tbc concentration can be had by testing the solution with a TwaddeH
kycfeomefcer.

from the mixing tank, alum flows by gravity to the storage task,
which pipe lines take it to the machines. The feed may be arrangp4
continuously at the breakers or beaters, or continuously at ttje