Fibres. 



296 



(October, 1911. 



the above experiment showed that the 

 objectionable colours were reducible, 

 the sulphate method of digestion seemed 

 to be clearly indicated. Before deciding 

 to follow it up it was necessary to give 

 some consideration to the rival method 

 of digestion by the sulphite process, 

 which does its work by sulphur dioxide, 

 partly in solution and partly in combin- 

 ation with lime as calcium bisulphite. 

 It does undoubtedly give good results 

 with coniferous pulps, not only in 

 quality and colour of product but in 

 economy also, though the latter is less 

 in comparison with sulphate than with 

 soda; but it is doubtful whether it 

 would give equally good results, so far 

 as colour is concerned, with the class of 

 woods now under consideration. In the 

 case of bamboo, which presents a colour 

 difficulty similar to the one we are now 

 dealing with (both, it will be noted, 

 being low country, tropical products), 

 the results have not been quite satis- 

 factory, as attested by the experiments 

 of Richmond (American Bureau of 

 Science, Manila), Coventry (Forest 

 Institute, Dehra Dun), and ourselves. 

 Then it is doubtful whether the sulphite 

 process is practicable in a tropical 

 country without the aid of a system of 

 refrigeration which would seriously 

 discount its economy. Its success de- 

 pends mainly on the absorption by 

 water or lime water, of sulphur dioxide 

 gas, an operation which is considerably 

 handicapped by any increase in the tem- 

 peratures of both water and atmosphere 

 over those normal intemperate latitudes. 

 On the whole, the balance inclined in 

 favour of sulphate, so it was resolved to 

 follow this up, leaving sulphite to be 

 enquired into on a future occasion. 



The success of sulphate digestion de- 

 pends largely on obtaining the proper 

 balance or proportion between the two 

 chief constituents of the liquor, and 

 a series of preliminary trials were 

 necessary to arrive at this. It may vary 



Hygroscopic moisture 



The following on the dry sample :— 

 (a) Water extract tannin, gum, mucilages 

 \b) Alcohol and benzine extract Rosin, 

 oil, wax ... 



(c) Hydrolysis by treatment for one hour 

 in 1 per cent, boiling sodium hydrate 



(d) Ash 



(e) Cellulose 



(J) Lignin, by difference 



considerably for different classes of 

 material. Ultimately a proportion of 

 6 of hydrate to 2| of sulphide appeared to 

 give the best results with these woods. 

 For want of time, no attempt was made 

 to fix the minimum quantities necessary. 

 These would certainly vary in each case 

 and will have to be subsequently deter- 

 mined. The present object was to solve 

 the colour problem of a whole class of 

 woods showing similar characteristics as 

 regards colour, and which could appar- 

 ently be dealt with by liquor contain- 

 ing hydrate and sulphide in the above 

 properties. The quantities required will 

 probably differ with each individual of 

 the class, but the proportions not ; so all 

 that was necessary was to secure a 

 standard liquor of sufficient density to 

 ensure reduction of the most difficult of 

 the species selected for trial, After 

 the class problem has been solved, it will 

 be comparatively easy to work down- 

 wards from tfce maximum density in 

 order to settle the requirements of each 

 individual. 



From the pulps scheduled as second 

 class in quality, a selection had to be 

 made of those which best combined the 

 commercial requirements of quality of 

 product with abundance and cheapness 

 of raw material. Having regard mainly 

 to the Tarai districts of the united Pro- 

 vinces, Mr. Clutterbuck selected Bombax 

 malabaricum, Salix tetrasperma and 

 Trervia nudiflora as those best fulfilling 

 the latter considerations. The selection 

 is a fortunate one from the other point 

 of view, for these also happen to be 

 among the best of their section in 

 quality and yield. The coniferous pulps, 

 scheduled as first class, were for the 

 present set aside, as it is already known 

 that they behave well under sulphate 

 treatment. 



These three were first submitted to 

 analysis, after being reduced to an air- 

 dry condition, with the following 

 results : — 



Bombax mala- Salix tetras- Trewia nudi- 

 baricum. 

 Per cent. 

 9.26 



510 



2-90 



13'30 

 2-60 

 49-00 

 27 10 



100-00 



perma. 



flora. 



Per cent. 



Per cent. 



11-38 



12-7 



4-75 



4-00 



290 



3-00 



8-00 



8-50 



1-00 



2-30 



53-20 



52-00 



30-15 



30-20 



100-00 



100-00 



Total to be removed by chemical action, 

 viz„(&),(c), (rf)and <J) 



