SUITABILITY OF LONGLEAF PIISTE FOR PAPER PULP. 7 



in ten-thousandths of an inch, and also as a ' 'strength factor/' which 

 is the average of the five pop tests divided by the weight per ream 

 of 500 sheets of paper, each measuring 24 by 36 inches. The relative 

 resistance of the papers to wear was determined by crumpling the 

 sheets in the hand, and all other properties mentioned, except 

 strength, were determined by feel or by observation without the aid 

 of instruments. 



DEFINITIONS OF TERMS USED. 



While the significance of most of the terms used in recording the 

 test data (Tables 1 to 10, inclusive) is either self-evident or sufficiently 

 clear in view of the previous discussion, there are several which may 

 require explanation. 



Water in cMps. — The amount of moisture is expressed in per- 

 centage of water, based on the calculated bone-dry weight of the 

 chips. 



All sodium compounds as Na^O. — This is the sum of the sodium 

 oxide (NagO) equivalents of the amounts of the several constituents 

 entering into the chemical charge. ''Total NajO" has an analagous 

 significance in the soda process. 



SulpJiidity.— The sulphidity of the liquor charge is the percentage 

 ratio of the NagO equivalent of the amount of sodium sulphide 

 (NajS) used to the amount of all sodium compounds present expressed 

 as NagO. 



Causticity. — This has a similar significance with respect to the 

 amount of caustic soda (NaOH) used. 



Initial volume of digester liquors. — The digester liquors include the 

 water in the liquor charge, together with the water in the chips and 

 the water condensed from the steam passed into the digester during 

 cooking. This condensation, of course, does not enter into the calcu- 

 lation of the initial volume. 



Apparent condensation. — The apparent condensation is the differ- 

 ence between the calculated i^nitial volume of the digester liquors and 

 the observed volume, as read from a water gauge, at the end of the 

 cook. It roughly represents the amount of steam condensing in the 

 digester during cooking, but does not take into account the volume 

 of the pulp and the differences in temperature of the initial and final 

 liquors, nor the steam and liquid lost during relief. 



SEMICOMMERCIAL TESTS. 



SULPHATE PROCESS. 



The object of the semicommercial sulphate cooks was to secure the 

 best quality of pulp with the highest possible yield. The severity of 

 cooking employed depends largely upon the use for which the pulps 

 are intended. If bleaching or easy bleaching pulps, such as are used 

 in book and other white papers, are desired, more severe cooking 



