centrifugal pump fixed at the bottom, and is discharged from it.continuously to the beater-roll, which is erected above the level of the reservoir.

A refining-engine is also used for the beating of wood pulps. It is a conical vessel lined with fixed projecting koives, and fitted with a beater-roll which is also conical. The roll is fitted with knives, and is so constructed that the distance between the rotating knives on the roll and those on the outer casing can be altered at will. This machine is very effective in brushing out the pulp, which is first partially treated in a beater. (Fig. 57.)

Sizing, Loading and Colouring. These operations are similar to those employed with esparto papers. The loading is incorporate with the pulp in

the engine, the rosin soap is then added and precipitated on the fibre by means of alum. Pulps intended for white papers are toned by the addition of traces of aniline blues and reds.

News and Common Printings.-The cheap papers of the present day are made almost exclusively from sulphite wood pulp and mechanical wood pulp blended in varying proportions.

The extensive use of mechanically prepared pulp for paper-making is entirely a inatter of commercial consideration, since the material is cheap and abundant, but from a technical standpoint it cannot be too strongly condemned on account of the deterioration which always takes place in paper containing ground wood.

Among other causes which have contributed to the cheap newspaper of modern times, improvements in machinery and mill organisation required for the production of a cheap paper take a foremost place. There is no special trade secret to be carefully hidden from the observant spectator, for the manufacture of a common news is now almost entirely a mechanical and engineering problem in which chemistry appears to play a secondary part. These improvements are mainly concerned with the machines used for preliminary operations and enlargements and alterations in the Fourdrinier machine. The use of beaters giving

etreater output is one of the most important features of recent development; ah adoption of rotating circular self-cleansing strainers for the beaten pulp

d

Fig. 56.- Tower" Beater.

passing on to the paper-machine is another improvement. (Fig. 58.)

The paper-machines have been increased in width until it is now possible to make a reel of paper 150 to 160 inches wide. The speed of the machine is 420 to 480 feet per minute instead of the modest 250 to 300 feet per minute of ten or fifteen years ago.

The drying-cylinders have been increased both in size and number, and improved in design to meet the extra work of evaporation rendered necessary by the greater speed. Careful attention to the details of transport of raw material, economy in the use of coal, the utilisation of every conceivable waste product, such as the machine backwater, the exhaust steam used for driving the machine engine, the waste heat of the gases in the boiler flues, and many other details of a highly interesting and technical character, has resulted in the production of the cheap newspapers.

Manufacture of news.-The pulp is broken up as usual in some form of disintegrator, such as a breakingengine or potcher. The engine is partially filled with water, and the sheets of mechanical pulp thrown in, together with the proper proportion

of sulphite. The quantities vary according to the quality of the paper, 65 to 75 per cent. of mechanical pulp being an average amount.

In many cases the mechanical pulp is broken up by special machinery instead.

Fig. 58.-Rotating Strainer. Specially suitable for "News" paper.

The pulp after beating is passed through this strainer.

of potchers, such as Wurster's kneading-engine (Fig. 61) or Cornett's breaker, both of which are useful for disintegrating pulp or waste papers.

The pulp is then discharged into the beating-engine, where it is beaten, sized, coloured, and mixed with china-clay.

The conversion of the beaten stuff into paper is a simple matter as far as the general principles of treatment are concerned, but in questions of detail relating

Fig. 62.-Double Drum Reeler. The reels from the paper-machine are
re-reeled, slit and finished off on this machine.

to the running of the paper-machine considerable skill is requisite to avoid faulty paper and undue waste of material.

The manufacture of 100 tons of news requires the following raw material, approximately: