502 abstracts: forestry 



It was found that the four conditions of cooking named influenced 

 the yield and properties of the pulp by influencing the severity of the 

 cooking reactions. Severity of cooking is an effect mainly of the amount 

 of caustic soda consumed per unit of wood. Increasing the amount of 

 concentration of the chemical or the pressure of cooking produces a 

 quicker reaction and hence one more complete in a given length of time. 

 Increasing the duration results in a more complete reaction because 

 of the longer time allowed for the available caustic soda to be con- 

 sumed. Greater severity of cooking is accompanied by a decrease in 

 the yield of crude pulp, and usually of screened pulp unless screenings 

 are present in considerable quantity. The decreased yields obtained 

 on more severe cooking result in a greater cost of wood and soda ash 

 per ton of pulp. As a rule, the small cost of bleaching powder incident 

 to the more easily bleached pulp produced by thorough cooking only 

 partially off'sets the greater cost of soda ash and wood. While the amount 

 of bleach required decreases with an increase in the severity of cooking, 

 a point is soon reached where the decrease in bleach is not commensurate 

 with that in yield. Increasing the initial amount of digester liquid 

 increases the condensation and steam consumption (and hence the cost) 

 because of the greater volume to be heated ; increasing either the dura- 

 tion or pressure has a similar effect because of the greater losses of heat 

 by radiation. Yields (bone-dry basis) of well-separated, unbleached 

 pulps as high as 56 or 58 pounds per hundred pounds of wood can be 

 obtained from aspen if the wood is of the best quality. Yields of from 

 54 to 55 per cent were obtained which required only from 10 to 11 per 

 cent of bleach. Yields under different cooking conditions varied from 

 46 to 58 pounds per hundred pounds of wood, or about 26 per cent. 

 Aspen may be successfully cooked with total durations of from 3 to 4 

 hours, and with from 20 to 25 pounds of caustic soda charged per hundred 

 pounds of wood, provided the other cooking conditions are properly 

 maintained. 



FiNDLEY Burns. 



FORESTRY. — Suitability of longleaf pine for paper pulp. Henry 

 E. Surface and Robert E. Cooper. Bulletin of the U. S. Depart- 

 ment of Agriculture, 72: 1914. Pp. 26. 

 The recent development in Europe of the sulphate process of paper 

 making, and the superior quality of the product made from resinous 

 woods, has turned attention to longleaf and other Southern pines as a 

 possible source of pulp in this country. These pines have long, thick- 

 walled fibers, and also high specific gravities, implying large yields per 



