﻿92 RICHMOND. 



were conducted with the view of determining the exact conditions condu- 

 cive of the best results in yield, color, ease of bleaching and strength 

 of the resulting pulps ; the conditions of the digestions ; namely, strength 

 of liquor, proportion of free and combined acid, proportion of liquor to 

 material digested, temperatures employed and duration of the cooking 

 are given below. 



SULPHITE BAMBOO PULP. 



Preparation. — Mature and seasoned culms of dwarf bamboo were 

 crushed between rollers and chopped into 3 to 4 inch lengths. Some 

 charges were thoroughly steamed before the sulphite liquor was added 

 and in others the liquor was run in upon the dry chips. Bamboo prepared 

 in the above manner forms dense, flat pieces which lie very close together 

 and which allow of being covered with considerably less liquor than an 

 equivalent weight of chipped wood. In all the digestions the weight of 

 the bamboo to the weight of the liquor used was ^ 5 to \ — that is, 15.12 

 liters (four gallons) of liquor was the maximum amount employed in 

 any case for4.5-|- kilos (10 pounds) of bamboo chips. 



Experiment 1. — Unsteamed chips were gradually heated througli a period of 

 four hours to a maximum temperature of 150° C. and maintained at this point 

 for four hours longer, giving eight hours for the entire digestion. The charge was 

 blown out under pressure; the chips were light, salmon-colored and apparently 

 digested. The yield of air-dry pulp was 56.6 per cent. The liquor carried 3.5 

 per cent of sulphurous acid, all combined as the bisulphite. 



Experiment 2. — Five kilos of well-steamed bamboo were covered with 13.23 

 liters (3.5 gallons) of bisulphite liquor, containing 3.45 per cent of total sulphur- 

 ous acid, and heated up directly to a maximum of 155°, this temperature being 

 maintained for a total period of ten hours. The chips were soft, light-brown in 

 color, and they bleached with difficulty. The yield of unbleached pulp was 51.7 

 per cent; the yield of bleached was 48.4 per cent, with a consumption of 22 per 

 cent of bleaching powder of 35 per cent available chlorine. 



Experiment 3. — Two and one-half kilos (5.5 pounds) each of steamed bamboo 

 and cupang wood were digested with 15.12 liters (4 gallons) of liquor of the 

 following composition: 



German method: Per cent. 



Total sulphurous acid 3.6 



Free sulphurous acid 2.4 



Sulphurous acid combined as monosulphite of calcium 1.2 



Lime, CaO 1.05 



American method: 



Total sulphurous acid 3.6 



Free sulphurous acid 1.2 



Sulphurous acid combined as bisulphite of calcium 2.4 



Lime, CaO ". 1.05 



The cook was heated up to 155° in four hours and maintained at 145° to 

 155° C. for a total period of ten hours. The yield of cellulose from the cupang 

 was 46.76 per cent, from the bamboo 47.32 per cent. 



