3 



•unit of length such as can only be given by a fibre bundle, as described above. To this spinning unit 

 it is convenient to give the term " filament," as distinguished from the ultimate fibres, or fibre cells, 

 ©f which it is built up. Given the filament, and confining our attention for the present to mechanical 

 or structural points, the value of a raw material will depend upon the length, together with the re- 

 lative fineness or degree of divisibility of the fibre bundles. 



The value of a yarn or fabric depends upon its strength and durability ; and these qualities in turn 

 upon the ultimate composition, structural as well as chemical. These are expressed by experimental 

 numbers, the results of investigation, and aie what we may term the constants of the fibre, they are de- 

 terminable by laboratory investigation, with the precision which necessarily attaches to scientific mea- 

 surements. First : in regard to the form or structure of the ultimate fibre. What we may call the uni- 

 versal element is the typical Bast fibre of Vegetable Physiology; a fusiform tabulated, elongated, 

 thick- walled cell. These cells vary but little in diameter from plant to plant ( mm.), but on the 

 other hand considerably in length. Comparing flax (25-40 mm.) with jute (1-3 mm.), for instance, 

 the disproportion is very great ; and, as we shall see, a considerable factor of the difference of value of 

 the fibres. Secondly : in regard to the composition of the fibre substances, i.e. the chemistry of the raw 

 materials. The fibre constituents, while they resemble one another generally in composition and properties, 

 nevertheless exhibit certain striking distinctions All the raw fibres are made up of a portion which 

 yields readily to the action of oxidising agents and alkaline solvents — which are in effect the agents 

 universally employed in bleaching the vegetable fibres and a more resistant portion which does not yield. 

 This latter is the cellulose basis of the fibres. The isolation of cellulose is therefore to the chemist what 

 bleaching is to the textile manufacturer. If the operation be followed, in regard to its influence upon 

 structure, with the aid of the microscope, it will be found to be attended by a disintegration, more or less, 

 of the filaments, i.e., that the cellulose obtained consists of the ultimate fibres or fibre-cells. It is the length 

 of these individual cells, together with their proportion in aggregate weight to the raw fibre, which are 

 the primary constants of the fibre. The common chemical feature of the vegetable fibres is, therefore, 

 that when treated exhaustively with oxidising agents and alkaline solvents, they yield a white lustrous 

 residue of cellulose; while on the other hand this constitutes a proportion in weight varying from fibre 

 to fibre, and is made up of ultimate fibre cells varying considerably in length from fibre to fibre. 



The following are the constants for the more important textile fibres : — 



Percentage of Cellulose. Length of ultimate Fibre. 



Flax ... £0.0 ... 25-40 mm. 



Hemp .. 80 ... 25-40 " 



Rhea ... 75.0 ... 60-200 " 



Jute ... 75.0 ... 3 « 



The above fibres are physiologically idenlical : they are the bast tissues of dicotyledonous annuals. 

 The filaments are bundles of from three to fifteen fibres, as seen in sections at any point, more or less 

 compactly welded together. 



The second of the greater divisions of the Vegetable Fibres includes the fibre bundles of the mono- 

 cotyledons, which furnish a large proportion of the raw materials for the rope-making industry. In these 

 the filament is not only a much larger aggregate, and therefore coarser, but is in many cases more com- 

 plex in structure. In place of a homogeneous bundle of bast fibres, we have bast fibres and vessels 

 cemented together and often enclosed in a cellular sheath. The bundles, moreover, as seen in section under 

 the microscope exhibit considerable variations from the cylindrical, which is characteristic of bast fila- 

 ments ; thus in the aloe fibre the crescent form prevails. The bundles, though containing other struc- 

 tural elements, are, however, for the most part made up of the typical bast fibre, of which we can often 

 count as many as 50-100 in the section. The dimensions of these fibres, as well as the percentage of 

 cellulose in the filaments of the more important in this class, are given below : — 



Percentage of Cellulose. Length of ultimate Fibre. 



Manilla ... 63.0 ... 3-6 mm. 



Phormium ... 67.9 ... 8-15 " 



Agave ... 76.0 ... 2-8 " 



So far we have taken the raw fibres as made up of cellulose and non- cellulose, the latter yielding 

 more or less readily to the action of oxidising agents and alkaline solvents. The non -cellulose," unlike 

 the cellulose, is a very characteristic constituent, in the sense that the raw fibres divide themselves into 

 two well-marked groups, according to its composition, viz. :— (1) the pectic ; (2) the lignified. In addi- 

 tion to their being sharply distinguished by their reactions, the union with the cellulose is much more 

 intimate in (2) ; so that whereas boiling with alkaline solutions suffices to hydrolyse and dissolve away 

 the pectic portion of the pecto-celluloses, the ligno- celluloses are not so resolved : in this and in many other 

 respects they have more the chemical characteristic of a homogeneous body. The distinguishing charac- 

 teristics of the ligno-celluloses are (a) direct combination with chlorine, the chlorinates giving an intense 

 coloration (magenta) with solution of sodium sulphite ; (b) a bright yellow colour-reaction with solutions 

 of the aniline salts ; (c) a deep purple with phloroglucol in presence of hydrochloric acid (cone.) ; (d) 

 conversion into an orange-coloured nitrate, on treatment with a mixture of nitric and sulphuric acids. 



Of the above-mentioned fibres, flax, hemp and rhea belong to the first group, jute to the second 

 while the monocotyledonous fibres, as might be expected from their more complex character, manifest 

 the properties of both groups. 



The pectic fibres, as a class, are superior to the lignified in respect of softness and divisibility of the 

 filaments. Moreover, it is remarkable that the characteristics of the latter group are always correlated 

 with shortness of ultimate fibre ; they are also generally inferior in regard to proportion of cellulose. 

 "We are now, therefore, in possession of the equivalents, in science, of the inferior position which they 

 ^occupy in commerce and the arts. Generally, moreover, we find that our constants and the inferences 



