Bulletin of the of Agriculture . mation of the sheet, heat in the driers, humid-ity at which the strength tests are made, and probably other factorsmust remain constant. Most of these, then, depend on the personalequation of the machine tender, and where some of the runs may bemade a week apart, conditions are likely to vary. This probablyexplains the irregularity of the strength results as given in Table they show anything at all, it is that above per cent the amountof combined S02 has no influence on the strength of the paper pro-duced but below that there is a tenden
Bulletin of the of Agriculture . mation of the sheet, heat in the driers, humid-ity at which the strength tests are made, and probably other factorsmust remain constant. Most of these, then, depend on the personalequation of the machine tender, and where some of the runs may bemade a week apart, conditions are likely to vary. This probablyexplains the irregularity of the strength results as given in Table they show anything at all, it is that above per cent the amountof combined S02 has no influence on the strength of the paper pro-duced but below that there is a tendency to decrease in strength. Photomicrographs of the pulps secured in cooks 75, 74, 72,. and 71are shown in Plates I, II, III, and IV. It will be noted that there isa gradual change in the appearance of the fibers. Cook 75 was madewith liquor containing per cent of combined S02, and cook 71with per cent. The former contains much lignified fiber, whilethe latter seems to be thoroughly cooked. Bui. 620, U. S. Dept. of Agriculture Plate. Pulp Produced in Cook 75. Jul. 620, U. S. Dept. of Agriculture Plate II.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagriculture, bookyear
