C—3A

noticed here. With a furnish of 101b. the consistency was very low, and the treatment given the pulp so drastic that the full strength was not developed. The colour was satisfactory in both runs, but the specks and shives were not thoroughly broken up, and the sheet was dirty. In a later run (No. 42) the furnish was beaten a longer time in the beater, and given a lighter brush, with the hope of breaking up more of the fine specks. A fairly clean sheet was produced, which was apparently satisfactory for a news sheet. Satisfactory strength and printing-qualities were shown by this sheet when run through the press of the Wisconsin Stale Journal. Run No. 29 was made, using sulphite cook No. 3277-1, in which insignis pine and tawa were cooked together. The pulp was overbeaten, however, and the strength was low. Substitutions of Rimu and European Larch for Insignis-pine Sulphite. Runs Nos. 31, 33, and 42 were made with substitutions of rimu and European larch for insignis pine. Run No. 31, in which 15 per cent, of bleached larch was substituted, gave a low bursting and a high tearing strength, indicating that more beating would have made a satisfactory news sheet. The colour was above the average. A considerably smaller amount of bleach should produce a colour satisfactory for this furnish. In run No. 33 15 per cent, unbleached rimu was substituted. The strength was low and the colour was rather dark. It would probably bo necessary to partly bleach the rimu pulp to give the desired colour, if used in the amount necessary to give the required strength. In run No. 43 15 per cent, of bleached rimu was used, with an improvement in colour, but the sheet was not up to the desired strength standard. Newsprint Runs using Semi-chemical Pulp. Run No. 35 was made on a furnish of 80 per cent, tawa cooked by the semi-chemical process, and 20 per cent, tawa groundwood. The strength and colour were poor, and it was impossible to run a lightweight sheet. Runs Nos. 36 and 40 were made on a furnish of 100 per cent, semi-chemical pulp. The strength was satisfactory, but the colour was dark and the sheet rather brittle. In run No. 41, 55 per cent, of semi-chemical pulp was substituted for the tawa sulphite in the news furnish with bleached larch. The strength and colour were slightly below the desired limits, and the paper was less opaque than some of the other samples. It is quite possible, however, that a satisfactory paper can be made by using the semi-chemical pulp in smaller amounts. One of the main difficulties in making a newsprint paper from semi-chemical pulp has been brittleness and hardness. In the tawa runs a consistency of 9 per cent, was used in refining the chips in the rod mill, which seemed to give a softer and less-hydrated stock that could be worked up in the beater. COMMERCIAL PAPER-MILL TRIALS. General. So far as the Forest Products Laboratory was concerned, only one factor was not covered in the experimental semi-commercial tests —namely, the translation of certain phases of the papermaking experiments to a mill-scale basis. As this is the customary practice of the laboratory, and all projects are considered incomplete until such times as a mill-scale test is possible, it was recommended that arrangements be made to establish commercially the results already reported. This recommendation was adopted by the co-operator, and arrangements made accordingly for the pulping and papermaking tests on a commercial scale. Previous laboratory experience had shown that the two major problems in connection with the production of a news-grade paper from tawa and insignis pine would be—(l) The development of sufficient strength from the tawa sulphite to offset the complete lack of this quality in the finely ground tawa mechanical pulp ; and (2) the elimination of shives from the tawa sulphite in the interests of a clean paper. The laboratory tests previously reported had shown that the first requirement involved hydration or beating of the tawa-sulphite stock, and the second a refining action of some sort by means of either Jordan, beater or rod mill. It had been demonstrated on a laboratory scale that both of these objectives could be accomplished by proper processing with any of the above-mentioned machines. The rod mill, however, was found to possess certain advantages, particularly in the elimination of shives. Paper-machine Run at the Great Western Paper Co. Mill. The operations of the Great Western Paper Co. at Ladysmith, Wisconsin, may be considered as typical of a newsprint or catalogue-paper mill. The sulphite and groundwood furnish is mixed in beaters, but all hydration and refining depends upon the action of the Jordan. Previous to carrying the laboratory results to the mill scale, papermaking runs had been successfully carried out at the laboratory, using the small Jordan for all of the necessary beating and refining. The results of these tests are shown in Table 22 under machine-runs Nos. 1 and 2. On the basis of these tests it was decided to make a trial run at the Ladysmith mill, and compare the processing possible in a newsprint mill, having only Jordan equipment, with results obtained at the laboratory. Accordingly several attempts to produce news-grade paper were made at Ladysmitb, as shown in Table 25.

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