October, 1911.] 



297 



Fibres. 



The loss by hydrolysis (c) was deter- 

 mined after exhaustion by (a) and (6), 

 and may be taken to cover pectous 

 matter and the weaker forms of cellu- 

 lose which, under any method of treat- 

 ment, would be lose by being hydro- 

 lysed into soluble matter. The larger 

 amount of this in Bombax, coupled with 

 the smaller quantity of lignin, would 

 indicate that this wood can probably 

 be successfully treated with weaker 

 liquor than the other two. 



A sulphate liquor was now prepared 

 containing hydrate and sulphide in the 

 previously mentioned proportions and 

 also small quantities of carbonate, sul- 

 phite and sulphate of soda in the 

 proportions usually found in factory 

 liquor prepared by aid of a recovery 

 plant. This was done in order to work 



as closely as possible to factory condi- 

 tions. The two first, however, are in- 

 sufficient in amount to have any appreci- 

 able effect on the operation, while the 

 sulphate remains quite inert. The 

 total strength of the liquor expressed 

 as alkali (Na2 0) was 7 '4 per cent., which 

 would include all but the sulphate. The 

 density 19° by Twaddles' hydrometer, 

 and sufficient liquor was used to just 

 cover the material after it had been well 

 tamped down in the digester. Although 

 the same liquor was used for each of 

 the three, the minor points of duration, 

 temperature and pressure were varied 

 in each case in accordance with their 

 behaviour as observed in preliminary 

 trials. The details of digestion, together 

 with a bleaching comparison of soda 

 process results, and the microscopic 

 examination, are as follows :— 

 Bombax Salix Trewia 



malabaricum. tetrasperma. nudiflora. 



(a) Quantity of liquor per kilo of wood.., 3,000 cc 



2,500 cc. 



2,500 cc. 



(6) Duration, temperature and pressure! 4 hrs. 120 lbs. 3 hrs. 140 lbs. 2 hrs. 140 lbs 

 above atmosphere 170° c. 183° c. 183° c 



J 176° c. 



(c) Yield of unbleached air dry pulp 



(d) Quantity of bleaching powder of 35 % 



strength percentage on weight of 

 the unbleached pulp ... 



(e) Colour obtained 



(/) Quantity of bleaching powder requir- 

 ed to produce a similar colour after 

 soda treatment 



(g) Microscopic examination : —Average 



length of ultimate fibre 

 Average diameter of ultimate fibre ... 



(h) Average weight of wood per cubic 



foot 



(i) Quantity required for one ton of pulp 



in cubic feet 



In each case the resolution of the wood 

 was complete and the pulp entirely free 

 from chips or undigested particles. It 

 was evident in the case of Trewia that 

 the treatment was somewhat in excess 

 of that necessary and probably as good 

 results would be obtained by digestion 

 at lower temperature. In the case of 

 Bombax it was considerably in excess, 

 with some loss of yields, in spite of both 

 duration and temperature being less 

 than in the other case. We may there- 

 fore expect that further experiment will 

 show it cau be reduced with weaker 

 liquor with an improvement in the yield. 



The remarks as to blea2hed colour 

 have the following significance : — 



Good white.— Suitable for fine printing 

 paper and common writings. 

 38 



37-47. 



183° c. 

 followed by 

 4 hrs. 100 lbs. 

 150° c. 



401 7. 



183° c. 

 followed by 

 5 hrs. 80 lbs. 

 162° c, 



41-3% 



14% 18% 13% 



Good white Cream white Good white 



24% 



Unbleachable 



22% 



2 m/m. 

 03 m/m. 



1*6 m/m. 

 025 m/m. 



1*8 m/m. 

 03 m/m. 



23 lbs. 



31 lbs. 



28 lbs. 



260 



180 



194 



Cream white.— Suitable for common 

 printing and newspaper. In regard to 

 strength and quality generally, I would 

 place these pulps as follows : Taking 

 spruce pulp as the type of European and 

 American first class pulps, and poplar 

 pulp as the type of those of the second 

 class, then Bombax comes out slightly 

 superior to poplar, and the other two 

 equal to it. The average length of the 

 ultimate fibre in all cases exceeds that 

 usually found in deciduous trees, and in 

 the case of Bombax approaches that of 

 the Conifers. The claim of the sul- 

 phate method to produce a stronger and 

 tougher as well as a better bleaching 

 pulp, is fully borne out by a comparison 

 with the results obtained by soda treat- 

 ment, and the most interesting feature 



