Now although the stems of the "Bamboo," after cutting and crushing, may, as I have shown, be dried (and will when dried give a yield of 60 per cent. of fibre), still their bulk and extreme lightness would preclude importing them to this country in their raw condition, not merely from their heavy cost for carriage, but from their liability to damage from fermentation. For these economical considerations, therefore, I propose to reduce the "Bamboo" into "Fibrous-Stock" where grown or produced.
It may be well, before entering into details of the process, briefly to explain the ordinary system employed for preparing fibres, or fibrous materials, as also rags, for Paper-making. This consists in sorting, cutting, cleaning, and, if need be, roughly opening them, followed by boiling in alkaline leys, after which they are well washed until cleansed from impurities in what is technically termed the rag or breaker engine, during which operation they are disintegrated or reduced into "Half-stuff," or semi-pulp, this being subsequently bleached and converted into pulp and paper.
As the object of my process is to produce a fibrous or tow-like Stock, retaining as far as possible the normal or natural condition of the fibre, and not "Half-stuff" or "Pulp," my system of treatment differs materially from the foregoing, more especially in the boiling and washing processes.
Both of these processes I conduct in a battery, or series of vessels (16, 20, or more in number), such vessels being connected together by pipes, or channels, furnished with valves, or cocks, so that communication between the individual vessels may be maintained, disconnected, and regulated as desired, in such manner that the vessels, being methodically charged in succession with the material to be operated upon, the heated leys (composed of caustic alkali) can be progressively conducted from vessel to vessel of the series, passing over and through the material placed therein.
The leys are thus used again and again, (each successive change, or charge of ley, carrying forward the extractive matters it has dissolved from the fibre with which it has been in contact) until exhausted or neutralized, (when they are discharged), fresh leys being methodically, and successively, supplied, until by degrees, the extractive matters combined with the fibre or fibrous material have been rendered sufficiently soluble, when hot water for washing, or rinsing, is in the same continuous manner run successively from vessel to vessel, over, and through, the material contained therein, until the extractive matters rendered soluble by the previous alkaline baths have been carried forward and discharged, leaving the residuary fibre sufficiently cleansed.
By this system of boiling in continuity, until all the effective alkali in the leys is exhausted or neutralized, I realize an economy of from 30 per cent. to 40 per cent. of soda over the ordinary process of boiling, and by the subsequent washing, or rinsing, in the same continuous manner, without removing the material from the vessels, the normal structure of the fibre is in a great measure retained, waste is minimized, and thus, while being thoroughly cleansed and freed from extraneous matter, the strength and staple of the fibre are preserved; a considerable saving of fuel results from the heated liquors being used again and again, less steam being required, as also less water, while at the same time economy of both labour and power is effected over the ordinary system.
Assuming the boiling and succeeding washing processes to be concluded, and the material ("Bamboo") in one of the vessels of the series in its regular succession, to be found sufficiently treated and cleansed, a final cooling water is run on and through the fibre, which is then drained, and the contents of the vessel (disconnected for the time being from the series) emptied into a waggon running on a railway, by which it is conducted to a press or otherwise to abstract all the remaining moisture possible.
The dry, or semi-dry fibre, is then submitted to the action of a willow, or devil, by means of which it is opened or teazed out, and converted readily into a tow-like condition, when it is dried by a current of heated air, induced by a fan-blast, and finally baled up for storage or transport, in a similar manner to Cotton or Jute.
In this condition of "Paper-Stock," it may be kept an indefinite length of time without injury, and when received by the Paper-manufacturer requires merely soaking down and bleaching, to fit it for making into paper, either by itself, or used as a blend with other materials, as desired.
The minuter details of my process for treating raw fibres, or fibrous material, for the manufacture therefrom of Fibrous "Paper-Stock," are fully described in my several Patents, the only variation so far as relates to "Bamboo" being the preliminary preparation of the young stems, the other portions of the process being substantially the same as in daily operation at the Ford Works, Sunderland, for the treatment of "Esparto," and other "raw fibres."