278 MODERN PAPER-MAKING

have been fitted with this rather expensive system, the experiment was a very
courageous one, and recently it has been applied successfully for pulp drying.
In the Minton dryer all the cylinders are enclosed, so that they operate in a large
air-tight compartment where the pressure can be reduced to about 73 inches
of mercury. Working under these conditions, water can be boiled off, and
thus no ak circulation is required. Drying is therefore quite uniform provided
the sheet is uniformly heated on the drying cylinders. Newsprint made on

[Edward Lloyd, Ltd., and Walmleys (Bury), Ltd.
FIG. 122.—VIEW OF THE WORLD'S LARGEST PAPER MACHINE

machines fitted with Minton dryers is more bulky and absorbent than ordinary
newsprint, and it takes the ink very well.
• Finishing.—Newsprint made in this country has achieved a very high
standard of quality, and one of the factors responsible for this is the super-
calender. To obtain the best results from the super-calender the moisture
content has to be carefully controlled. Because of the difficulty, already re-
ferred to, of drying paper really uniformly, it is necessary to over-dry slightly,
and then to damp the paper to the desired moisture content to give the best
results from the super-calender. It is difficult to give any very definite figures
for moisture content, but normally, after drying and before damping, there
should be about 6 to 8 per cent of moisture in the sheet, and the finished paper
should contain at least 8 per cent of moisture.