Chemistry of pulp and paper making . cooks there have been condensed a small amountof oil and a hquid containing aldehydes, ketones, alcohol, ace-tone, etc. From small scale cooks Bergstrom has obtained thefollowing yields of alcohol based on the dry wood used. Per cent Fichte (Picea excelsa) o. 67 Kiefer {Pinus silvestris) o. 67 Pinus palustris o. 68 Pinus echinata ; o. 66 Aspen {Populus tretmdoides) o. 67 Birch (Betula alba) o. 81 Gum (Eucalyptus) o. 83 Bates: Dissertation, Columbia University, 1914. Veitch and Merrill: Bureau of Chem., Bull. No. 159. s Saylor: Fr. Pat. 428,678, April 19, 19
Chemistry of pulp and paper making . cooks there have been condensed a small amountof oil and a hquid containing aldehydes, ketones, alcohol, ace-tone, etc. From small scale cooks Bergstrom has obtained thefollowing yields of alcohol based on the dry wood used. Per cent Fichte (Picea excelsa) o. 67 Kiefer {Pinus silvestris) o. 67 Pinus palustris o. 68 Pinus echinata ; o. 66 Aspen {Populus tretmdoides) o. 67 Birch (Betula alba) o. 81 Gum (Eucalyptus) o. 83 Bates: Dissertation, Columbia University, 1914. Veitch and Merrill: Bureau of Chem., Bull. No. 159. s Saylor: Fr. Pat. 428,678, April 19, 1911. ^ Aktchourine: Fr. Pat. 433,424, Aug. 11, 1911. ° Williamson: U. S. Pat. 1,025,356, May 7, 1912. ii8 THE SODA PROCESS At the completion of a cook the contents of a rotary digesterconsists of material thoroughly reduced to the fibrous condi-tion while that in the stationary digester still retains verylargely the shape of the original chips. Rotary digesters aredischarged by blowing off pressure until the heads can be re- Baffle. Discharge Piipe Fig. i6. Blow Tank or Separator moved and then emptying the contents by revolving the digesters are emptied by blowing the entire chargeunder full pressure through a pipe leading from the bottom ofthe digester to a blow pit or some form of steam separator. Avery satisfactory device of this sort is shown in Fig. i6. Thestock enters tangentially at such high speed that it hugs the WASH PITS 119 wall of the separator while the steam escapes to the center andout through the ventilator. On blowing the charge the sud-den release of pressure causes violent evolution of steam fromthe moisture in the chips and this, together with the mechanicalaction of passing through the discharge pipe, causes completedisintegration into the fibrous state. The blowing of a digester causes a very large waste of has been estimated that in blowing a digester thereescape into the atmosphere 34,400 lbs. of steam within a peri
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