GROUND-WOOD PULP. 



15 



tion of steamed wood pulp occurs in the grinding process, either due to 

 the dissolving of material which has been converted to a soluble state 

 or the grinding of the softer portion of the wood — the springwood — 

 to flour and the subsequent loss of it in the white water. There is a 

 characteristic odor of burned sugar during the steaming of wood, and 

 possibly some of the wood fiber is converted into sugar. 



The condensed liquor from the steamer has a very corrosive action 

 on the iron and it is possible that in order to satisfactorily protect 



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HOURS OF STEAMINQ 



Fig. 7.— Effect of duration and pressure of steaming on the yield of pulp. (Spruce runs 103 to 107 and 114 



to 119, inclusive.) 



the metal it might be desirable to add small quantities of sodium 

 carbonate to the water when the boiling process is used. This, of 

 course, would not apply when the wood is steamed. 



The liquors which condense during the steaming of the woods 

 may have considerable commercial value, particularly when resinous 

 woods are used. The equipment employed in the Wausau laboratory 

 was not of sufficient capacity to make it possible to study this 

 problem carefully, but an indication of the nature of the condensed 

 liquor can be obtained from the following analyses of material 

 secured from a mill steaming wood commercially, in which case 

 approximately 5 cords of wood were used for each charge. Un- 

 fortunately no means were available for measuring the total condensed 



