﻿PHILIPPINE FIBERS. 91 



was employed. The heat was applied by direct flame and the charge was 

 always left in the digester after the completion of the cook until the 

 following morning. The chips of all the experiments reported in the 

 above table were of a light, salmon color when discharged, and the liquor 

 was a clear brown and still contained free sulphurous acid. The pulp 

 washed and beat easily to nearly white, soft fiber. Analyses of the 

 unbleached fibers given in Table jSTo. 9, page 93, serve to indicate the 

 extent to which the incrusting matters were removed, under the corre- 

 sponding digestion conditions. 



SULPHITE PULP FROM FIBEES OTHER THAN WOOD. 



Within recent years numerous attempts have been made to apply the 

 bisulphite or acid treatment to the manufacture of cellulose from the 

 cereal straws ; this was pointed out in a previous paper n but the siliceous 

 nature of straw has heretofore stood in the way of a satisfactory isolation 

 of the cellulose by this method. 



Dietz 12 proposes first to remove the greater proportion of the ash 

 content of the straw before submitting it to the action of the sulphite 

 liquor. He has shown that a preliminary treatment with the theoretical 

 quantity of hydrofluoric acid, calculated on the basis of the silica content 

 of the straw, in the form of a 0.5 to 1.25 per cent solution, is capable of 

 reducing the 1.5 to 3.7 per cent of silica normally present to less than 

 0.05. After such treatment, the straw is said to be quite suitable for 

 digestion with bisulphite liquors. The best conditions for boiling the 

 straw thus purified are given by an oi'dinary calcium bisulphite liquor con- 

 taining 3.6 per cent total sulphurous acid, of which 2.4 per cent is free 

 and 1.2 per cent combined. The boiling should be regulated so that 

 a pressure of 3.5 atmospheres is reached in an hour and maintained for 

 three hours. By this procedure the author obtained a 42 per cent yield 

 of pulp which bleached well with 13 per cent of bleaching powder. 

 Whether the partial removal of the silica in this manner will prove 

 to be economically practicable remains to be seen. The increased yield 

 of straw cellulose and the short time required to produce it, should 

 be considered to be very attractive on the continent, where this material 

 is quite highly prized for paper stock. In view of some results to be 

 described later, obtained in pulping bamboo by means of sulphurous acid, 

 I do not believe it to be necessary partially to remove the mineral constit- 

 uents from highly silicated materials, before their treatment with sulphite 

 liquors. 



Other raw materials besides the Philippine woods already described, 

 from which sulphite pulp has been prepared in this laboratory are hemp 

 waste, old rope, jute gunny sacks and dwarf bamboo. The experiments 



11 This Journal ( 1906 ) , 1 , 437. 



^Ztschr. f. angew. Ghemie. (1905), 28, 648. 



