Composition of Wood 



The rosin content was determined by thoroughly 

 extracting 25 gram portions of the very fine chips 

 with ether in a Soxhlet extractor fitted with 

 ground-glass connections. The rosin was finally 

 dried to constant weight by heating in a Freas 

 electric oven at 105. Occasional rolling of the 

 flasks hastened the removal of the ether and turpen- 

 tine. Checks within one or two tenths of a percent 

 were considered satisfactory. 



By drying the above chips at 105 after extrac- 

 tion with ether a figure was obtained representing 

 the percentage of " actual wood" free from mois- 

 ture, rosin and turpentine. This value has been 

 used in computing the true pulp yields. 



To determine the effect on the rosin of extraction 

 by alkali, weighed quantities of the sample chips 

 were heated near the boiling point in dilute caustic 

 soda solution. By repeated decantation and heat- 

 ing with fresh caustic, there was ensured complete 

 saponificationof the rosin and thorough washing of the 

 chips. The combined fractions thus obtained were 

 precipitated with acid and the rosin extracted with 

 ether. To minimize the tendency towards emulsific- 

 ation of the humus and to make the operation as simple 

 as possible, the alkaline liquor was placed in a separa- 

 tory funnel, acidified with HC1 or H 2 SO4, and 

 shaken with ether while still slightly warm. The 

 suspension of humus between the water and ether 

 layers prevented complete removal of the lower 

 aqueous layer, although the greater part could be 

 drawn off directly. The clear, upper portion of 

 the ether extract was decanted through a small 

 plug of absorbent cotton into a second separatory 

 funnel. The residual gelatinous humus was then 

 washed several times by decantation with fresh 

 ether and finally filtered on the cotton and washed 

 with solvent. The small quantity of water was 

 then easily removed in the second separatory and 

 the rosin was determined in the usual way. This 

 cycle gave values for rosin which were a few 

 tenths of a percent lower than the direct ether 

 figure. Possible decomposition of gums by the 

 caustic and slight mechanical losses of rosin during 



27 



