Bulletin of the of Agriculture . creened pulp, yield of screenings, and bleachconsumption. A decrease in the combined S02, other conditions being constant,has a tendency to shorten the duration of the cooking time. In-creasing the amount of combined S02 to 1 per cent has a tendency tomake the pulp fighter, but the color remains constant when thecombined S02 is increased over 1 per cent. The color determinationsfor the machine-made sheets were made by means of a tint photometer(p. 22). The higher the parts black, the darker the sheet. The yield of screenings and unscreened pulp re
Bulletin of the of Agriculture . creened pulp, yield of screenings, and bleachconsumption. A decrease in the combined S02, other conditions being constant,has a tendency to shorten the duration of the cooking time. In-creasing the amount of combined S02 to 1 per cent has a tendency tomake the pulp fighter, but the color remains constant when thecombined S02 is increased over 1 per cent. The color determinationsfor the machine-made sheets were made by means of a tint photometer(p. 22). The higher the parts black, the darker the sheet. The yield of screenings and unscreened pulp remains constantwhen the combined S02 is decreased to 1 per cent, but any decreasebelow this shows a sharp increase in both of these factors. The PRODUCTION OF SULPHITE PULP FROM SPRUCE. 15 yield of screened pulp increases as the combined S02 is increased to1 per cent, but beyond this remains constant. The amount ofbleaching powder necessary to bring the pulp to a standard whitedecreases as the combined S02 is increased to about 1 per cent, but. 80 120 160 200 0 10 20 30 44 46 48 50 PARTS BLACK DURATION Of COOK-HOURS YIELD OF UNSCREENED PULP - PERCENT 1 J_# 1 —,, —t,— - ._. -j-p 4 i| 4. ! ir r 1 —_— ?1 »/ . 11_ _ Pr - \ === k- \ !k. V^C ..... j ., .... ^^ = > —i—i—i— —i— —i— ]— . 42 44 46 48 SO YIELD OF SCREENED PULP -PERCENT 12 3 4 5SCREENINGS-PERCENT 0 10 20 30 40 SOBLEACH-PERCENT Fig. 8.—Effect of varying the amount of combined S02 in the cooking liquor. any increase beyond this point does not produce any further changein color. The amount of combined S02 does not seem to hare much influenceon the different factors studied, provided it is over 1 per cent, butany decrease below this caused marked changes in the character and 16 BULLETIN 620; U. S. DEPARTMENT OF AGRICULTURE. yield of pulp. One cook was made where the cooking liquor con-tained only per cent of combined S02, and the result was thatthe chips came out of the digester looking as
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagriculture, bookyear
