The tailings are recovered to be re-passed through the mill, and, in time, for the most part are also ground to the desired degree of fineness. A certain proportion of residue defies reduction in this manner, but it is not discarded. It is retrieved to be used in the manufacture of coarse brown paper. Two methods of grinding, even in the vertical mill, are practised. The one known as the wet process involves the addition of water to the dust, which thus becomes hydrated, the resultant saw-pulp, as it is called, being somewhat similar to the familiar wet mechanical pulp. The alternative process is described as dry grinding, the sap in the wood constituting the only moist agent. It may be mentioned that, in the very earliest attempts to emulate the wasps’ paper-making process, the experimenter ground the wood to dust by applying the log to the face of a grindstone which was revolving, water being the lubricant, the practice recalling the grinding of tools. The particles of wood fell, with the water, into the trough beneath. The surplus water was drawn off, leaving a mashy residue or pulp--hence the name. In grinding the sawdust the coarse material is reduced to a fine powdery substance, soft and silky in texture when dry, but which retains the essential fibrous characteristic, though naturally the length of the individual fibre is extremely minute. But pulp so produced possesses one advantage for the paper-maker--it demands no preliminary boiling. It can be discharged direct into the beater, as the machine which prepares the raw material for the paper-making machine is called, with the waste-paper, sulphite or mechanical pulp, or a mixture of both, it only being necessary for the agitation of the contents of the beater to be conducted thoroughly to bring about the perfect blending of the ingredients. I have emphasized the circumstance that this saw-pulp may only be considered as a diluent. This may be varied from 10 to 35 per cent. according to the quality of the paper desired. The issue of the _Times_, dated June 15, 1918, was printed on paper containing 20 per cent. of this saw-pulp, but I have seen other newspapers the paper for which was prepared from pulp diluted to the extent of 35 per cent. with the saw-pulp. With the accumulation of experience in the working up of this material marked improvements are to be recorded in regard to quality of the resultant paper which has enabled dilution to be carried to an enhanced degree without imperilling the factor of strength which the finished product must possess to enable it to be passed through the newspaper printing machine at a speed of 500 feet per minute without breaking. Under modern conditions it is difficult to determine whether or not saw-pulp has been introduced into the composition of the paper, which testifies conclusively to the perfection of production.