ions of fyt J "A very interesting and elaborate monograph, valuable both from a scientific and an industrial point of view. ... A most valuable contribution to tinctorial literature." Chemical News. "It is rather singular that Yorkshire, the county most thoroughly identified with wool, should send forth a good scientific essay dealing with the structure of the cotton fibre, the speciality of Lancashire. We are afraid the County Palatine will not be able to return the compliment. Be that as it may, every one will be quite satisfied to accept a gift from any good source. It is probably owing to the accident that Dr. Bowman, whose many scientific acquirements peculiarly fit him for the task, though a resident of Yorkshire is a cotton spinner of high repute. . . . We cordially advise that all our readers interested in the subject dealt with should procure the work at once, as its perusal will be found highly gratifying. " Textile Manufacturer. "Dr. Bowman is a practical cotton spinner as well as a scientific man. We have probably said enough to show those of our readers who are interested in cotton spinning that the volume is worth their attention. Apart from the learn- ing and labour involved in the production of the work, few readers will fail to be struck with the enthusiasm of thoroughness that possesses the author, whose inculcation of conscientiousness in technical industry is enforced even more by example than by precept." Manchester Examiner and Times. "In this elaborate monograph Dr. Bowman gives, with additions, the substance of three lectures delivered by him before the Conncil of the Bradford Technical School. His work is a guarantee that in the matter of technical education nothing is likely to be wanting. ... A highly meritorious attempt to bring wide scientific and general knowledge to bear upon a trade question of the highest importance. " Manchester Courier. "Dr. Bowman may be congratulated on having produced a work which is likely to be useful, not merely for the technical information which it conveys, but because of its suggestiveness and the intelligent interest in the materials and process of the cotton manufacture which it may awaken." Manchester Guardian. "Those who are connected with the cotton manufacture, however wide may be their knowledge of the material in which they are working, will no doubt learn something from the teachings of Dr. Bowman, who goes over a wide field, and who works with the idea of stimulating those who are young and energetic, and who have life before them, to give their attention to the first principles of the processes in which they are engaged, so as to find out the best means of giving perfection to the most minute parts of the raw material." Glasgow Herald. "Undoubtedly the very best yarns which can be produced are a long way from anything like perfection, and our cotton manufacturers have been too much inclined to neglect the scientific side of their business. Dr. Bowman's work, which by the way is illustrated with some really excellent diagrams, will serve a useful purpose if it has the effect of drawing their attention to this fact." British Trade Journal. OPINIONS OF THE PRESS. "The author possesses the unusual advantage of having both a scientific and a practical acquaintance with his subject. We must pronounce the book valuable not merely to the student, but also to the experienced practical man." Chemical Review. "The book is a valuable contribution to the literature of cotton, and no spinner can read it without profit and pleasure." Manchester City News. "Few persons hare more actively contributed, either in the laboratory or in the workshop, to the advancement of science, as applied to cotton spinning and its cognate industries, than the author of the work referred to. It is well worth study, and as a work of reference it should find a place in every establishment where the manufacture of cotton is carried on." Yorkshire Inventor and Manu- facturer. "All who take an interest in the progress of our two leading manufactures will join us in the hope that the present volume is but number one, and that in due course a similar work on the wool fibre will follow, as volume two, from the same talented pen. The work will form a valuable addition to the library, and a most useful adjunct to the cause of technical education. . . . The work is most beautifully got up, and it is at once a credit to the author, and an evidence of his zeal in the cause of technical education." Halifax Guardian. "Not slothful in business we knew was Mr. Bowman's characteristic, but this work on the cotton fibre indicates a rare devotion ; he has endeavoured to master his calling in all its details, and has striven to solve difficulties which, once mastered, will give fresh impetus to this gigantic and ever increasing industry. . . . The book is admirably printed, and the illustrations are excellent. It deserves a large sale amongst cotton manufacturers, dyers, and other tech- nologists." Halifax Courier. "La recherche toujours croissante de connaissances techniques dans les differentes branches des arts et manufactures a provoque dans ces derniers temps 1'apparition d'ouvrages speciaux sur les multiples genres de 1'industrie textile. Le plus recent est le volume que nous annon9ons du docteur Bowman, qui est une monographic complete de 1'etat de nos connaissances actuelles touchant la fibre du coton, considered comme matiere premiere des produits manufactures. La haute situation scientifique de 1'auteur, sa collaboration a une des plus grandes manufactures de coton d'Angleterre, dont il est le chef, 1'ont tout particuliere- ment mis a meme de traiter ce sujet au double point de vue scientifique et pratique. ... En Angleterre, on apporte une attention croissante aux sciences, qui sont la base de tous les precedes manufacturiers. Seule, cette connaissance peut permettre de lutter avantageusement sur tous les marches du globe. Kien ne pouvait paraitre plus a propos que cet ouvrage d'un homme qui est une autorite comme le docteur Bowman : tous devraient 1'avoir, tous devraient le lire^ y compris les ecoles techniques, qui do ivent 1' adopter partout ou elles existent." Moniteur Scientifique. Quesneville. Siroctore 0f % oitan Jfihrt. O EH EH O HI THE STRUCTURE OF THE COTTON FIBEE IN ITS RELATION TO TECHNICAL APPLICATIONS; O3 CO C^l ""3* OO OS l> O O O O i-H o o o o o 9 > S I I From this table it will be seen that there is con- siderable variation both in the length and diameter VARIATION IN FIBRES. 21 of the fibres of cotton grown in the same district a difference which we shall afterwards see arises from a variety of causes, and is influenced also to a larger or smaller extent by the character of the seasons from year to year. As a rule, also, we see from this table that the longest fibres have also the smallest diameter, and are therefore finer and silkier in the staple. The extreme variation in the length of staple is as follows : American( Orleans) '28 of an inch. Sea Islands 0*39 Brazilian 0'28 Egyptian 0'22 Indian (Surat) 0'25 The extreme variation in the diameter of the indi- vidual fibres is Inch. Fraction. American (Orleans) 0-000390 Sea Islands 0-000360 Brazilian 0-000340 Egyptian 0-000130 Indian (Surat) 0-000391 From these tables it appears that Egyptian cotton is the most regular both in length and diameter of the fibre, the greatest difference being -$$ of an inch and -^V^ of an inch respectively ; while Sea Island cotton, although possessing the greatest length and fineness of fibre, exhibits also the greatest variation, viz., -^j of an inch in length, while it varies YTTT f an inch in the diameter of the individual fibres. It will also be seen that the variation in the diameter is proportionately very much larger than 22 STRUCTURE OF THE COTTON FIBRE. the variation in the length ; and indeed this pecu- liarity strikes the eye at once when looking down into the tangled plexus of a lock of cotton placed within the field of the microscope, and the feeling seems almost irresistible, that considering the varia- tion in the fibres, it is a matter of astonishment that cotton yarns can by any mechanical process be made with the regularity in the diameter of the threads which is usually obtained. These figures are not very easy to carry in the mind, or indeed to picture to the mind as a distinct idea, especially to those unaccustomed to microscopical investigations and measurements ; and we can perhaps best conceive of the relative dimensions of a cotton fibre if we remember that supposing we were to magnify a single fibre of American cotton until it was one inch in diameter, it would be a little over 100 feet long, while a Sea Island fibre of the same diameter would be a little over 130 feet. Each individual fibre, also varies in diameter in different parts of its length, being, however, when fresh from the boll, as a rule pretty uniform until about three- fourths of its length is reached, when it gradually tapers off towards the end farthest from the seed to about one-fifth of its maximum diameter, and ends somewhat abruptly not unlike the extremity of a worm, the end usually exhibiting a somewhat more cylindrical form than the general length of the fibre. If we examine a sample of ordinary cotton, however, we find that very few of the fibres are perfect, as they THE COTTON POD. 23 get broken in the process of ginning, which separates the cotton from the seed, and they usually therefore terminate in a ragged edge which is sometimes very useful to show the structure of the tube when treated with various reagents. We may have some idea of the tenuity of the cotton fibres when we remember that from 14,000 to 20,000 individual filaments of American cotton only weigh one grain, so that there are about 140,000,000 in every pound, and each hair only weighs on the average about the xri*r^ P ar ^ f a grain, and if the separate fibres were placed end to end in a straight line one pound weight would reach 2,200 miles. If we examine a cotton pod in the earlier stages of its growth, we find that it is attached to the stem of the parent tree by a small stalk. Immediately below the pod itself we have a ring of leaves, four or five in number, forming what botanists call a polysepalous calyx, and between which and the seed vessel itself there are the withered petals of the corolla which formed the coloured part of the flower of the tree. The pod or capsule itself is the developed ovary, and consists of a hard outward sheath, which is divided longitudinally into a series of valves differ- ing in number in the different varieties of cotton (usually three in Egyptian and four or more in American). These valves have each a rib or septum projecting inward from the inner surface and dividing the capsule into separate compartments in which the seeds are confined. 24 STRUCTURE OF THE COTTON FIBRE. In the earlier stages of growth the seeds appear to be attached to the inner margin of the carpilliary septa at the point of junction of these septa, that is to say, at the inner side of the carpel where the two edges of the carpilliary septa unite, and they are con- nected to it by vascular bundles which proceed from below upwards, traverse the carpels, and send a branch to each seed. At the same time, there is also a considerable development of cellular tissue forming a ridge or placenta on the margins of the septa to which the seeds are attached. The seeds continue this attachment until they have attained their full size and the growth of hair on the outward surface of the seed has commenced. It then becomes gradually absorbed, and the seeds themselves are forced into the centres of the cavities by the gradual development of the hairy covering. The structure of the cotton pod will be readily understood by a reference to Plate II., where we have a longitudinal and transverse section of an Egyptian cotton pod. Here the seed vessel or carpel is divided into three separate compartments which each contain a lock of cotton surrounding the seeds which are contained in them. The method of growth of the seed appears to be like that of a nut, viz., by the successive deposit of concentric layers on the inner surface of the outer envelope. In a growing seed these successive layers are distinctly visible even to the naked eye when the seeds are cut in two, the layers growing less dense as we proceed inwards until we come to the oleaginous, milky fluid which Plate II E E Fi c. 2 Longitudinal and Transverse Section of Egyptian Cotton Pod. A. Stem. B. Section of Calyx. C. Section of Carpel D.Midweb with, seeds attached. E. Section of Seeds. G Plexus of young Cotton fibres. DEVELOPMENT OF FIBKE. 25 fills the centre cavity, and which gets smaller and smaller as the stage of maturity is reached. The development of hair commences at the further end of the seed from its point of attachment, and gradually spreads over the surface as the process of growth continues. The first appearance of the cotton fibre itself occurs a considerable time before the seed has attained its final growth, and commences by the successive develop- ment of cells from the surface of the seed. These cells appear to have their origin in the second layer of cellular tissue, and force themselves up through the epidermal layer itself, making good their attach- ment to the outer layer by the gradual absorption of the cell walls of the outer layer which they displace, and form a larger cell from the outer surface of which the linear propagation of cells commences. This point, however, needs further investigation, as, unfortunately, I have had few opportunities of watch- ing the method of growth in the earliest stages. These germinal cells are distinguished in their earlier stages by the thickness of the cell wall in proportion to the diameter of the cell, and the method of growth is by the successive linear development of cells, the cell wall at the point of junction being gradually absorbed until an exceedingly elongated cell is pro- duced which constitutes the cotton fibre. During this period of growth the cell walls are continually becoming more and more attenuated, and gradually fill up the whole interior of the seed pod with an 26 STRUCTURE OF THE COTTON FIBRE. apparently tangled plexus of young cotton fibres, whose growth and the increase in the number of the fibres, as the seed continues to throw them off, tend to assist in bursting open the seed pod when the time of maturity arrives. The length of the hairs vary considerably on differ- ent parts of the seed, and indeed it appears doubtful whether they ever attain their full length until after the pod has fully opened and the fibres themselves have been exposed to the drying and ripening effect of the air and sun. As a rule, the longest fibres are those which grow on the crown of the seed where the cell development makes its earliest appearance, and the shortest are always found at the base of the seed. These very short fibres usually remain attached to the seed after the process of ginning is complete, and when examined under the microscope appear to exhibit signs of having been arrested in their growth by the gradual drying-up of the seed, arising from the lessened activity of the vital action, when the inward growth of the seed itself was completed. Unfortunately, how- ever, some of these short immature hairs also are removed by the gin along with the longer fibre, and when they exist in large quantity in any sample of cotton are difficult to remove, and form a source of great trouble and annoyance in the carding process, when they aggregate into small clusters and lumps called technically by the trade "neps." It ought, however, to be mentioned that these "neps" can also be produced in cotton which is perfectly free from EAELY GEOWTH OF FIBRE. 27 them by imperfect mechanical manipulation in the earlier stages of manufacture, but there is no difficulty in detecting in any sample of cotton from which of these causes the "neps" arise, as in the case of artificially produced "neps" the cluster consists of fragments of broken fibre, while in the natural "neps" the short fibres are comparatively whole and unbroken. In their earliest stages the young cotton fibres appear to have a circular section arising from the comparative thickness of the tube walls ; but as these walls gradually become thinner by the longitudinal growth of the hair and the pressure to which they are sub- jected by the contact of surrounding fibres enclosed within the pod, they gradually become flattened, and just before the pod bursts the outer wall of the cells have become so attenuated in the longest fibres as to be almost invisible even under high microscopic powers, and present the appearance of a thin, pellucid, transparent ribbon. With the bursting of the pod, however, a change occurs. The admission of air and sunlight causes a gradual unfolding of the hairy plexus, and the rapid consolidation of the liquid cell contents on the inner surface of the cell wall give them a greater thickness and density, which is further increased by the gradual shrinking in of the walls themselves upon the cell contents. There is also a gradual rounding and thickening of the fibre, which increases by the deposition of matter on the inner wall of the cell. As this action is not perfectly uniform, arising from the unequal exposure of different parts of the fibres 28 STRUCTURE OF THE COTTON FIBRE. to light and air, it causes a twisting of the hairs, which is always a characteristic of cotton when viewed under the microscope, and the flat collapsed portions of the tube form so many reflecting surfaces, to which the brightness of the fibre when stretched tight in the fingers is no doubt due. Another change also occurs at this stage, a change which corresponds to the ripening of fruit. In the earliest period of their formation the growing cells are filled with juices which are more or less astringent in character, and which can be readily tested by applying the tongue to the juices which flow out of the cells when a young pod in its immature form is cut in section. Under the influence of the light and air these cell contents undergo a chemical change, in which the astringent principles are replaced by more or less saccharine or neutral juices, until in the perfectly ripe cotton fibre the cell walls are composed of almost pure cellulose, which is one of the most neutral of all chemical substances, and of which we shall have to speak more hereafter. The ripening of the fibre and the opening of the boll permitting the natural expan- sion of the hairy contents, draw out the seeds from their original position, and when the boll is fully expanded it is exceedingly difficult, if not altogether impossible, to separate the hairs which have their attachment to each particular seed from each other, the whole forming a feathery fibrous mass within which the seeds are enshrined in the most irregular manner. The appearance of the fibre when examined under DESSICATION OF FIBKE. 29 the conditions in which it is usually received for commercial purposes, viz., after separation from the seed by the process of ginning, and after it has been subjected for some time to the pressure which has been put upon it by the hydraulic press used in pack- ing the bales, undoubtedly differs very widely from the appearance of the fibre when it is in the process of growth and attached to the seed pod. It differs indeed in the same way that hay does from grass, since after the separation of the fibres from the seed upon which they grew a gradual process of dessication sets in, accompanied by the gradual shrinking of the fibre, arising from the drying up of the various cell contents and consequent shrinking of the cell walls. Microscopical investigation was first applied to the cotton fibre by Mr. Bauer, in the year 1834, in order to illustrate a paper by Mr. Thompson, of Clitheroe, on the "Mummy Cloth of Egypt," but the drawings were not accurate, and it was not until some time later that Mr. Yarley, of London, and afterwards Mr. "Walter Crum, F.E.S. of Glasgow, in 1863 made a much more thorough and scientific examination, and published drawings which are remarkably accurate and exact in their delineation of the appearance of the fibre. When examined under the microscope the general appearance is that of an irregular, flattened, and somewhat twisted tube, the tubular form in some cases being entirely lost, and the appearance resembling, more than anything else I can think of, that of a wrinkled, twisted, irregular ribbon. A twisted 30 STRUCTURE OF THE COTTON FIBRE. collapsed tube is, however, the most general form, and from the fact that the shrinking and collapsing is in the greatest number of instances due to the dessicating process which we have already named, the edges of the tube still preserve a somewhat rounded appearance, so that the form is not unlike that which would be pre- sented by twisting and creasing a double-headed T railway rail, the same as is in common use on all the railways in this neighbourhood, supposing that the two heads had a circular opening in the centre of their section, with a thin slit down the centre of the junction between the two. This peculiar form of the cotton fibre renders it very easy to detect cotton when mixed along with other hairs or fibres, such as wool or silk, as they each present very marked individual charac- teristics when compared with each other. This will be readily seen in Plate III., where I have exhibited side by side the appearances presented by fibres of wool, cotton, and silk. The Chinese wool presents us with the appearance of a number of cups with thin irregular edges placed one within the other, and forming by their successive extensions the length of the hair. These cup-like rings are really a series of plates or scales developed on the outer surface of the epidermal layer which forms the sheath or cover- ing of all animal hairs. The peculiar property which wool possesses of matting or felting arises from the catching of these serrated edges one within the other, or rather a kind of interlocking action; and this also renders wool peculiarly fitted for spinning into Plate 325 DIAMETERS. A. Fibre of Chinese Wool. B C D E. Leicestershire Wool Cotton. Silk. Mohair. SEKKATIONS ON WOOL. 31 threads, as these interlocking plates or scales prevent the fibres from slipping or drawing out when once the twist has been put into them. We shall afterwards see that this action is accomplished in the cotton fibre in a different manner. The other two fibres of wool Leicestershire hog and mohair also exhibit a similar scaled or serrated structure, but in each case the markings are finer and less regular. In the Leicester- shire wool there are about 1,450 of these serrations in a single inch, while in the finest class of mohair and Saxony wool they reach between 2,000 and 3,000 to the inch. It may not be uninteresting to notice the difference in the number of these serrations per inch in other classes of wool, and also the difference in the diameters of individual fibres of these different wools and hairs, so that we may be able to compare them with cotton. These measures are taken from average hairs from the middle of the fleece, since I have found them to differ considerably in different parts of the animal, especially on the neck and hind quarters. They may be roughly tabulated thus: Number of scales Diameter per linear inch. of fibres. East Indian wool 1,000 -^ of an inch. Chinese 1,200 Lincoln 1,400 Leicester 1,450 , South Down 1,500 Merino 2,000 Saxony 2,200 Calf hair China grass , English flax 32 STKUCTUKE OF THE COTTON FIBRE. Silk presents an entirely different appearance. It looks like a transparent glass rod with few surface markings, and is really a rod of consolidated flexible gum, composed of a material called "sericin" by chemists, which is secreted from two large glands, one on each side of the body of the silkworm, and the grooved form which the silk fibre often presents under the microscope arises from the joint or partition where the product of the two large glands are made to adhere together so as to form one long fibre, which is sometimes continuous for more than 1,500 feet. The cotton fibre is quite different from any of these even in other respects than the peculiar twisted character of the filaments. When examining the fibres under the microscope with reflected light, the whole surface of the tubes seems to be covered over with transverse and longi- tudinal ridges or creases. So much so is this the case, that not unfrequently the tubes appear to be corrugated in the direction of their length, but the corrugations are very seldom continuous, and very frequently broken by ridges in the transverse direction as though there had been originally strengthening rings within the tubes which had resisted the collapse, and those portions of the tube are therefore prevented from collapsing to the same extent just there as in the intervals between them. These apparent rings are, however, so very fre- quently absent that it does not seem to me that we can take them as a necessary part of the structure of APPEAKANCE OF FIBKES. 33 the tube. In others the surface seems to be more or less cracked all over in very irregular patches, as though the shrinking and collapsing of the fibre had been accompanied by an actual rending of the external sheath of the tube. This appearance is most frequently observed when the fibre presents the least appearance of tubular structure, that is to say, when the edges appear to be almost as flat as the centre, as though, if it ever possessed a tubular structure at all, it was so thin in the thickness of the tube walls that it was capable of. a complete collapse at the edge as well as the centre. In samples of cotton fibre taken from the growing boll, the appearance when viewed with reflected light, or as an opaque object, is like a tangled series of silver rods or twigs, with more or less corrugated marking along them in the direction of their length, formed by the folds of the outer cell wall, with its waxy sheath, and exhibiting much less of the twistings which are such a peculiar characteristic of the fibre when in a dryer and more inspissated condition. If transmitted light be used an entirely different appearance is immediately presented. The surface markings become almost invisible when compared with the complicated structure which is revealed within the tubular walls, and which is quite visible through the transparent pellicle which forms the outer coating of the fibre. Indeed, the transparency of the whole fibre is so great that, except in certain cases in D 34 STRUCTURE OF THE COTTON FIBRE. which there appears a slight endochrome or colouring matter in the cell contents, the plexus of lines occasioned by the dark shades of the creases on the two surfaces renders it extremely difficult to make out the nature of the internal structure, without sub- jecting the fibre to some process which will colour the interior cell walls, and thus enable their structural peculiarities to be discerned. So great is the diversity in nature that we may say with truth that each fibre has a structure of its own, and differs in many particulars from all its fellows. Generally speaking, however, I have found that they may be divided into three classes : 1. Those where no internal structure is apparent. 2. Where the structure seems to be simply tubular, with a well defined transparent cell wall. 3. Where the structure is tubular, and the interior of the cell filled with secondary deposits which almost entirely fill up the internal cavity, giving the fibre a dense, almost opaque appearance. Of course there are various degrees in the distinct- ness with which these characteristics are manifested in different filaments, and some observers have made many more divisions dependant upon the length, thickness, and number of convolutions or twistings present in the various fibres in a given length ; but it seems to me that for practical purposes these divisions are sufficient to cover all the various appearances presented, at any rate in the cultivated cotton. The first of these classes occur most frequently in CLASSIFICATION OF FIBRES. 35 early and unripe cotton, and, singular to say, also apparently in cotton which is over ripe, or has been left on the tree for some length of time after the full maturity of the opening of the boll has been attained. In both these cases the outer sheath of the fibre appears to be of extreme thinness. In the one case arising no doubt, as we have already seen, from the fact that the fibre has been detached from the seed before the period when the filling up of the interior of the elongated cellular sac which forms the fibre has commenced, and the other by the process of re-absorption, which always sets in when any organic structure has reached maturity, and which gradually while it may give an increased density to the outer wall materially decreases its thickness. There is yet another form in which this want of internal structure is observed, and which is of peculiar interest to us as technologists, by the tendency which some of the fibres appear to have to form certain portions of their length with a solid structure which seems quite homogeneous and transparent, but quite incapable of permeation by any of the ordinary pro- cesses which will inject the other parts of the fibre. We have an analogous case in the formation of what are called " kemps " in the wool fibre, where the fibre exhibits no indication of internal tube, but seems to consist of a hard structureless I had almost said an ivory-like consistency, where the cell lengths which form the fibre appear to be smaller and closer together, and where the thickness of the cell walls 36 STRUCTURE OF THE COTTON FIBRE. and their smoothness quite prevent any of that mat- ting or felting action which is essential when it is to be used for textile purposes. Sometimes, but not very frequently, I have found this kempy structure to be continuous throughout a whole fibre, and in nearly all these cases I have observed that such a fibre has resisted, as might have been expected from the greater hardness and density of the hair, any twisting or shrinking action, and appears more like a trans- parent glass rod with more or less surface markings almost like silk. Usually this kempy structure is very irregularly distributed through the fibres, and I have reason to believe that it is much more frequent amongst short than long fibres, and in all probability varies with the character of the weather during the year, and to some extent with the nature of the soil and geographical position of the place of growth. We shall afterwards see that this structure is possibly a case of reversion, a tendency to reproduce the form of the wild variety from which the domesticated or cultivated cotton was originally derived, since in the wild varieties of cotton this kempy structure is much more frequent. We can, however, easily see how very important it is that further experiment and observa- tion should be made in reference to this matter, as since these solid fibres are quite incapable of receiving any dye, except mechanically on the surface, they may be the cause of irregularity and variation in the colour of yarn and goods. So inert are these kempy fibres that if a number of them be separated they resist the SOLID STRUCTURELESS FIBRES. 37 dyeing action of those colouring matters which seem to have an affinity for the fibre itself, and the action of which form ihe strongest argument in favour of a chemical rather than a mechanical theory of cotton dyeing, and however firmly the colour appears to be fixed upon them it can be almost entirely removed by the action of running water or mechanical friction. I once examined a sample of Surat cotton where almost every fibre exhibited irregularities in structure of this character, occurring at intervals throughout their length something like the knots on a corn stalk, where it appeared as if their office in the economy of the plant was to strengthen the tube which was quite visible in the interval between these kempy rings. I have very seldom found them in Egyptian cotton. The thin, ribbon-like structureless fibres, however, spoken of before, occur more or less in all cottons, and are capable of receiving a slight tinctorial tinge under the action of dyes, which however never seem to be able to bring them up to the full standard of colour which can be attained in the perfect cellular cotton. The probability is, therefore, that in all bolls of cotton some of the fibres never attain maturity from some cause or other, either their position on the matrix preventing their getting a sufficiency of light or nourishment, or some other reason interfering with the perfect development of the hair, and the proportion of this fibre being more or less dependent on the character of the season and the health of the plant. The second class of fibres exhibit a distinct tubular 38 STRUCTURE OF THE COTTON FIBRE. structure, in which the walls of the tube are well defined, but where they differ in the thickness of the wall from a thin, apparently structureless transparent pellicle to a solid, well-defined tube thickness, where they shade into the third variety. This third class of fibres appear to me to be the typical cotton fibre, since they seem to possess the power of permitting various dyeing materials to pass through into the in- terior of the tube walls, where in some cases, they appear to be retained in dense crystalline masses. When acted upon in this way by many chemical reagents the rigidity and solidity of the tube walls appear to be increased, and in many instances its thick- ness also. It seems as if in this fully-matured fibre the central cells up which the sap passed during the period of growth had been fully absorbed into the tube wall, when the full length of the hair was reached, and the vital action which kept the cell contents in activity arrested, and while the interior cells are fully matured they are shrunk in towards the denser walls which form the outer sheath, but without losing their structure, so that they are ready to be expanded again inwards when their interior is filled either with fluid or solid contents, as the case may be. In this class of fibres the central tube is always well defined. Of course, as in the case of the second class, the irregularities and twists in the fibres are quite visible, and they shade into the first and second varieties, but they form by far the largest portion of every cotton sample; and hence, as we TYPICAL COTTON FIBRE. 39 have stated above, may be taken as the typical fibre. In Plate IV. we have a fair representation of these three classes of fibre. The glassy, structureless fila- ments which have resisted almost all twisting action, and only in certain parts indicate the existence of a tubular structure; the thin, pellucid unripe fibres which have such attenuated walls that they look like a flattened ribbon, shading into a well-defined tube wall and twisted into corkscrew form; and the fully matured fibres, where the tubular form is perfect and the twisting regular and symetrical, while the tube walls are solid and present distinct evidences of cellular or laminated structure. We may therefore define a typical cotton fibre as a long tubular compound vegetable cell, from 1,200 to 1,500 times as long as it is broad. The outer or enswaithing sheath of which appears to be a con- tinuous liber cell of pure cellulose, similar to those which occur at the -outside of the cambium-layer of dicotyledons, or the cells which form the outer part of the fibro-vascular bundles of monocotyledons, and which are also found in the branches of those contain- ing no spiral structures; and the inner or thickening layers of the tube consist of secondary cellular deposits upon this outer epidermic layer, or else are formed by a gradual thickening of that layer itself arising from the consolidation of the protoplasm or juices which supply nutriment, and which by in some measure preventing the collapse of the thin outer 40 STRUCTURE OF THE COTTON FIBRE. sheath, strengthen and render it more elastic and expansible. The extreme outer layer appears to be formed of a continuous membrane, since no power which I have been able to apply to the microscope has enabled me to detect even the most minute openings through its substance, and it is on to this elementary pellicle that the cellular layers which appear to form the thickness of the tube walls are deposited in such a manner that they are, while united to it, still capable of being separated from it into distinct laminae. I am aware that there are many botanists who make a distinction between the primary layer of liber cells and the thin pellicle which forms the sheath of such a vegetable hair as cotton, but after all the difference is only one of degree not real kind, since it is extremely probable that the thickening of these hair walls arises from the successive deposits which occur within them during the process of growth, exactly in the same way as within the liber cell of wood fibre, only that these secondary deposits are not concentric like the layers within the liber cell of wood fibre, but consist in the development of a series of cells one over the other, but whose walls are collapsed in upon each other, and which do not, except with the use of reagents, usually exhibit any signs of cellular structure ; and in section, from their extreme tenuity, they can hardly be distin- guished from a thickening of the outer pellicle or sheath itself. Hence, in the process of growth from the first formation of the hair within the boll to the mature fibre as it is fully ripe and ready for picking, we Plate IV 325 DIAMETERS. A. Glassy, Structureless fibre. B. Thin,pelucid, unripe fibre. C. Half ripe fibre, with thin Cell wall. D and E . Fully Mature and ripe fibre with full twist and thick, well defined cell wall. SECTIONS OF COTTON FIBRE. 41 have every possible stage of this formation presented to us, from the immature fibre, where the thickening of the outer sheath has not yet begun, up to the perfectly ripe cotton. In that stage of early growth, either within the unopened boll or just after its first opening, where the length of the tube is almost reached, a cross section of the hair presents us with only a single line like the cross section of a steel band, presenting no structure, or at most only a single line to indicate that it has any internal opening, the same as would be exhibited by an exceedingly thin tube squeezed flat under such pressure as to completely collapse the tube and form it into a ribbon. As the develop- ment of the hair proceeds the thickness of the tube wall increases, and the ribbon-like structure gives place to a more and more distinct tubular form, when a central opening appears down the centre of the oval hair section. In the perfectly ripe cotton the tubular form is distinctly seen in section, although from the want of strengthening layers or rings, or the deposit of the secondary layers in the spiral form, which always gives increased rigidity, the shape is very seldom cylindrical; indeed, I have never seen it so except at the extreme end of the fibre, where there appears to be a tendency to form a more solid structure on account of the less diameter of the tube in proportion to the thickness of the walls. Plate V. exhibits a number of these sections, where 42 STRUCTUEE OF THE COTTON FIBRE. the different stages of growth are clearly seen. The young unripe fibres which show no indications of tubular structure, or only a faint line at the edges of the ribbon, and the half-developed filaments where the attenuated tube walls have a certain thickness, but are quite distinct from the full round tube walls which mark the perfect maturity of the fibre. In all cases, except at the extremity of the hairs, however, even the fully-matured fibres exhibit a more or less collapsed condition of the tube, which evidently arises from the drying-in of the cell contents, and we shall afterwards see that under the action of certain reagents the sections may be made to assume a much more rounded and full appearance. It is extremely difficult, on account of the disad- vantage under which I have laboured in not being able to examine the cotton pods as they present their various aspects of growth upon the trees in their native fields, to say exactly the whole of the conditions which the fibres present in their various stages of development; and when the cotton has been picked, ginned, pressed, and transhipped, it is not unlikely that the cells composing the inner layers will have shrunk from the gradual drying up or transfusion of their cell contents, and become closed in upon the wall formed by the outer epidermic layer, when they will form along with it by the gradual drying up of the gummy matter which forms the residuum of their inspicated juices, a more or less homogeneous structure, in which it is only to be expected it would be all but Plate V 450 DIAMETERS. Sections of Cotton Fibre. A. Unripe unmatured fibres. B. Half ripe fibres. C. Fully matured and ripe cotton. D. Section of fibre showing laminated cell walls. LAMINATED STRUCTURE OF FIBRE. 43 impossible to make out these thin secondary cell walls, especially in cross section. This indeed appears to be the case, and in no single instance have I been able to make out clearly the exact mechanical form which this thickening of the fibre in ripening assumes in cross section, although I have had several instances when a more or less laminated appearance has presented itself. This appearance of lamination of the tube thickness in cross section has to be carefully distinguished from the lines which are produced by the interference of the luminous rays, and which, as all microscopists know, are very apt to be formed at the edges of objects which present a sufficient thickness to cause a sensible retardation of the rays of light passing through the object and those passing close by the edge of it; and especially when the object glass is not quite in focus, or not quite corrected for the thickness of the covering glass. Making all allowance, however, for these optical illusions, I have met with several instances where a distinct lamination has been visible when examined by direct sunlight, especially when the tube walls have been injected with coloured solutions as when in the dyed state; and they have been easy to distinguish from these diffraction lines by the fact that they were not continuous, but irregu- larly distributed through the cell wall, where they made themselves manifest by the more or less shady appearance which the illuminated tissues presented when compared with the enclosed spaces. In a series of experiments, which I shall in my 44 STRUCTURE OF THE COTTON FIBRE. next lecture more fully detail, I found that certain chemical reagents acted unequally upon all parts of the cell walls, some portions of which were more readily dissolved than others. It seems, therefore, probable that in the tube wall the inspissated juices which formed the cell contents, and which were arrested in their change when the vital action of the cell was stopped, form a cementing gum which closely unites the cell walls together, and, while they confer a certain amount of rigidity to the tube walls, also resist the entrance of any fluids, and render any process of dyeing more difficult and uncertain. They also form a medium through which the light is more perfectly transmitted than if the cell walls were in the form of separate laminae, and thus render the optical examination of the structure of the fibre much more difficult and uncertain. INTRODUCTION. 45 LECTUKE II. IN our last lecture we considered the general scope of our subject, and went more particularly into the botanical relations of the cotton fibre and the method of its growth. We also looked at the general structure of the fibre as it is presented to us in the ordinary cotton of commerce, and saw that such cotton really consists of fibres which differ considerably in their charac- teristics, and which differences arise from the various stages of growth of the fibres, as well as from malformations and other accidental circumstances. We saw that the fibres usually present in any sample of ordinary cotton might be divided generally into three distinct classes, which shade into each other, and the general characteristics of each of these classes may be seen from the examples figured in Plate IV. We also arrived at the conclusion that the fully ripe and typical cotton fibre consists of a hollow cylindrical tube, with well-defined walls composed of cellulose, and which walls appear to increase in 46 STRUCTURE OF THE COTTON FIBRE. thickness as the ripening process advances towards maturity. It is a matter of considerable difficulty to determine the exact method in which the tube walls become thickened in the ripe fibre, because previous to the bursting of the pod within which the seeds with their hairy filamentous covering are enshrined, the cotton fibres themselves present the most attenuated appear- ance without the least indication of any well-defined tube wall, and it is not until they are exposed to the sun and air that the swelling and thickening up of the thin pellicle which forms the outer sheath of the cotton fibre takes place. It was formerly supposed that there was a variation in the method in which this occurred in the cotton fibre from that which is the general rule amongst ordinary vegetable cells, and which consists in the formation of secondary deposits within the liber walls which constitute the exterior envelope. This appeared all the more probable, because there was an apparently entire absence in the cultivated cotton fibres of any of those special forms of deposit which confer rigidity and strength upon the cell wall, and which it seemed, judging from analogy, would have been present more or less in such an elongated cell as a cotton fibre. These special characters generally present themselves under two different types, accord- ing to the extent to which they cover the primary membrane. In one case they are applied as a general layer over the cell wall, absent merely at dot-like or ACTION OF EEAGENTS ON FIBRE. 47 slit-like points where they do not cover the primary membrane, and thus give rise to a pitted structure sometimes appearing even reticulated. In the other case, the secondary deposits are more sparing in quantity, and are applied over lines which form a definite pattern upon the primary liber wall, and which generally assumes a spiral form in the direction of the major axis of the cell. The absence of any indication of this spiral form of deposit within the walls of the ordinary cotton of commerce seemed to indicate that there was a special method in which the thickened cellulose membrane was formed, and I carefully examined a very large number of fibres with a view to determine how this took place. In working at this subject, I may mention, for the information of those who wish to follow up the work, that I found a solution of iodine, chloride of zinc, and iodide of potassium, treated with sulphuric acid (as recommended by Professor Schultz), a very useful reagent, and with it was able to detect a distinct spiral tendency in some samples of Austrian gun cotton, which of course had previously been treated to change it from ordinary cotton into gun cotton with a strong solution of sulphuric and nitric acid. Through the kindness of Mr. Higgin, of Liverpool, I was supplied with a very fine collection of mounted specimens of cotton fibre, which were collected by him some years ago, and which range from the wild cotton of Africa to the finest Sea Islands cotton from Edisto; and the result of this examination 48 STRUCTURE OF THE COTTON FIBRE. has modified the opinions which I formerly entertained respecting the possibility of secondary deposits in the spiral form occurring within the cotton fibre, since there is no doubt but that it is distinctly visible both in the wild African cotton and in a specimen of rough Peruvian. In the latter it is especially noticeable. It therefore appears that cotton is no exception to the ordinary growth of vegetable structures, and that the thickening of the tube walls arises from the presence of secondary deposits which, in the wild state, may assume a spiral form, so much so that they prevent the collapse of the tube walls, and resist any bending or twisting of the fibres themselves, which look more like hairs or some other vegetable fibre than cotton. Cultivation seems to produce a lessening of . this tendency to the spiral form in the secondary deposits and a greater liability to the collapsing of the tube walls from the fibrillse being disposed more or less longitudinally. The twisting of the fibre itself, which is so marked a feature in the ordinary commercial cotton, especially when fully ripe, may therefore be the indication of a remote ancestoral tendency, and is a characteristic which we shall after- wards see is of great importance in cotton as a raw material for technical purposes. The fibres of wild cotton exhibit the appearance of very large and weak tubes when compared with cultivated specimens, and while they are somewhat curved, and possess traces of joints at irregular intervals, their rigidity and inflexibility render them Plate VI 300 DIAMETERS. Cotton Fibres showing Spiral Structure A and B. Fibres of Wild African Cotton. C and D. Fibres of Coarse Peruvian Cotton. CONSTRUCTION OF CELL WALLS. 49 quite unfit for manufacturing purposes. Plate VI. gives a general idea of the appearance presented by the wild fibres, in which the spiral structure is distinctly visible, and the fibres of rough Peruvian cotton probably supply us with an example of the tendency which all domesticated plants exhibit to revert to the original stock when more or less neglected in cultivation. In the cultivated cotton it is not easy to determine the exact manner in which the cell walls of the fibre are mechanically constructed, for there are strong reasons for believing that the secondary deposits are not concentric, but probably form a series of extremely flattened cells, which can by dessication close in upon the original membrane, so that they cause the wall to appear extremely thin when in the dried state, but form a more or less spongy form of cellulose, which readily increases in volume by the imbibation of any soluble matter with which the fibre may be brought into contact. I have not, however, been able to make out so distinctly as I should have liked the exact structure of these walls, on account of the fact that the great transparency of the cellulose pellicles which form this compound inner sheath, resists, even when treated with reagents, the highest microscopic powers, but it is quite clear that they must be built up in some way which permits of their being increased in thickness by the action of certain reagents upon them, which force asunder the layers or cells of which they must be composed, E 50 STRUCTURE OF THE COTTON FIBRE. In 1863 a series of experiments, with a view to determine this point, were made by Mr. Chas. O'Neill, of Manchester, who treated the cotton fibres with a reagent suggested by Schweitzer, viz., an ammoniacal solution of oxide of copper, which possesses the power of dissolving cellulose without decomposing it. Writing on this subject, he says: "I believed that in cotton hairs I could discern four different parts. First, the outside membrane, which did not dissolve in the copper solution. Second, the real cellulose beneath, which dissolved, first swelling out enormously and dilating the outside membrane. Thirdly, spiral fibres, apparently situated in or close to the outside membrane, not readily soluble in the copper liquid. These were not so elastic as the outside membrane, and acted as strictures upon it, producing bead-like swellings of a most interesting appearance ; and, fourthly, an insoluble matter, occupying the core of the cotton hair, and which resembled very much the shrivelled matter in the interior of quills prepared for making pens. It is interesting to note that the outside membrane, which was insoluble in the men- struum, and impermeable to it, could not be found on cotton which had been submitted to the treatment of the usual bleaching process ; it had either been dissolved away, or, what seems most probable, some protecting resinous varnish had been removed, and then it became soluble. The same general results were obtained by acting upon cotton with sulphuric acid and chloride of zinc, and by acting upon certain EXPERIMENTS WITH SOLVENT. 51 kinds of gun cotton with ether and alcohol. Mr. Dancer, of Manchester, an experienced microscopist, repeated these experiments- some time after, and he saw all that I described, but considered that the spirals seen did not exist in the cotton hair, but were formed by the twisting or rotating of the hair under the influence of the solvent. "* In repeating these experiments, I found that the appearances varied with the nature of the cotton and the degree of maturity which the fibre had attained. In the thin, pellucid hairs, where the ribbon-like structure pertained, most of them were dissolved without showing any indication of structure whatever, but they curled up under the influence of the solvent, almost looking as if they were alive. The distinctly tubular fibres swelled out something in the same way as when treated by the Mercerising process of which we shall have shortly to speak and then dissolved, without showing any traces of structure or cell con- tents; but in some of the more opaque and sturdy fibres a distinct separation into layers was visible, and a coagulation of the inner cell contents not unlike the pith in a quill pen described by Mr. O'Neill. In treating the fractured end of a rough Peruvian fibre, where the inner layers of cellulose were drawn out from the outer layer, there was a distinct separation into fibrous bands, which resisted the action -of the solvent longer than the enclosing layers, and in some * Calico Printing, Bleaching, and Dyeing. By Charles O'Neill, F.C.S. Vol. ii., page 2. 52 STRUCTURE OF THE COTTON FIBRE. even an indication of a double spiral structure; but no power at my command with the microscope, and no reagent which I could use, revealed to me a cellular structure either in the cellulose layers amidst which these spirals were embedded or in the outer sheath or membrane which enclosed the whole fibre. I was specially anxious, if possible, to resolve this outside membrane into its constituent cells, so as to detect the mechanical cause of the separation of the anular layers when subjected to the action of certain chemicals, and believe that it is really, notwithstand- ing its great length, one continuous cellular layer ; and probably those within are similarly continuous and of great tenuity. In the common cotton sedge (Eriophorum polystachyum), which is not, however, a true cotton, the division of the cells is quite distinct, and it is quite possible that this might also be seen if looked for in the coarsest staples of wild cotton grow- ing in its native habitat. In 1850 a discovery was made by Mr. Jno. Mercer. He found that if cotton fibres were soaked in a solution of caustic soda of a specific gravity of 1*3 or 1*4, they became stronger and fuller, converting thin and coarse cloth into strong and fine, and at the same time giving greatly increased and improved powers of receiving colour, and also making the colours more permanent. Thus three important and very remark- able alterations occur at the same time, the fibre becomes stronger, it acquires increased attraction for colouring matter, and it also becomes finer. It MERCERISING PROCESS. 53 frequently happens that chemical processes have a weakening action on the fibres subjected to them, but in this case it is the reverse, and for which a probable explanation can be given. The cost of this Mercerising process seems, however, to have hindered its adoption in practice, and the results which were anticipated to flow from the discovery have not been realised to the extent which seemed probable when it was first announced, while the improvements in spinning, which enable finer and fuller yarns to be produced, have in some measure rendered it unnecessary in a large class of goods. In a valuable paper communicated to the Chemical Society, and published in the " Chemical Journal " for 1863, Mr. Walter Crum, F.R.S., pointed out that if the unripe and perfectly flat cotton fibre is sub- jected to this process, it at once assumes the round, solid form of ripe cotton, differing from the naturally matured and ripened fibre only in being smaller, more generally cylindrical, and in having a larger aperture in the centre; and he adds "It may now appear not improbable, that, by the natural process of ripen- ing, an effect is produced similar in character to that which is given to the unripe fibre by artificial means, and that the natural expansion may be ascribed, not to the importation of a new kind of matter coating the interior of the original cell wall, but to a strengthening and rendering elastic of the mem- brane already existing of the wall itself, so as to produce the separation from each other of the cells or 54 STRUCTURE OF THE COTTON FIBRE. laminae, or other structure of which it must consist." If this be the case, the tube walls of a fully-matured and ripe cotton fibre really consist of a series of tissues of pure cellulose, which are separated from each other by series of intervals of more or less dense cellular tissue, forming a series of capillary surfaces, which can act with the utmost energy upon any liquids in which the fibre may be immersed, and which will account in the fullest manner for the extraordinary absorbent power which the cotton fibres possess. He believed that the thin, pellucid outer sheath of cellulose acts as a dialyser, and under the laws of osmotic action the surrounding liquid passes into the inner cells, whose thin transparent walls act in like manner, and by a series of these actions the liquid is gradually passed inward, until it finally reaches the inner tube itself. Upon these observations he formed the opinion that the dyeing of cotton was almost a purely mechanical operation; but as we shall have to look at this question more fully in our third lecture, we may dismiss it for the present. This dialysing process will of course take place to the greatest degree when the formation of the cotton fibre has been most perfect, and when, as in the fully ripe and mature fibre, all the cell contents have been changed into pure cellular tissue, leaving the free cellular spaces perfectly unfilled, and therefore like so many capillary tubes, able to exert the utmost force of which they are capable in drawing inward and retain- COTTON OIL. 55 ing any liquids which may be presented to the outer surface of the prepared tube walls. We say prepared, because, associated with the seed, and also to some extent with the fibre itself, there is a peculiar waxy oil which resists, so long as it remains on the surface of the outer sheath, the entrance of any liquids through the membrane which has not a solvent or chemical action upon it. The quantity of this oil contained in the seed and fibre varies with the seasons and with the degree of ripeness of the boll. Large quantities of cotton seed oil are expressed from the seeds after the process of ginning is completed, and the presence of this oil, to a more or less extent, in the cells and on the surface of the cotton fibre, as an oily wax, is probably one of the causes why an elevated tempera- ture which is essential, especially to fine spinning is necessary in the manufacture of cotton into yarn. As the temperature falls the oily wax tends to become stiff and gummy, and prevents the proper drawing of the fibre; while its presence amongst the thin laminations of the cell walls gives a greater elasticity to the fibre, and render it less liable to sudden rupture. The gradual drying up of the more volatile portions of this oil in the fibre, leaving the remaining portion thicker and stiffer, may also, and probably does, account for the fact noticed by most spinners, that new crop cotton seems to work better and makes less waste than as the season advances, and which I have often heard expressed in the words "New crop cotton has more nature in it." Upon the 56 STKUCTUKE OF THE COTTON FIBRE. presence of this oil also depends the "setting" pro- cess, which all cotton fibres require after they are spun into yarn, in order to increase its strength and take away the curl produced by the twist in the thread, a process which in the case of single yarns is usually accomplished by keeping them for some time in a cold and moist place, where the natural oil becomes stiffened and dry after the high temperature to which it has been subjected in spinning, and in the case of yarns for doubling purposes by subjecting them to a high temperature under steam pressure before the process of doubling the threads. There is also a certain time required before the fibres, which have been subjected to torsion in the putting in of the twist, acquire a permanent set in the new position which their substance is forced to assume in the thread. A part of the setting process also depends upon the subsidence of the electrical excitement which is in- duced in the hair by the friction to which it is subjected in the manufacturing process. This is often seen in winter time, in dry frosty weather, especially in combed yarns, where the fibres are mechanically drawn out by the action of combing, and this electrical excitement renders them wild and hairy until they have been left for some time in a moist place or in a vacuum. This action can be prevented to a certain extent by placing the machinery in metallic connection with the steam or gas pipes by a wire the latter is best. The consideration of the nature of this oily wax really brings us to the next part COTTON WAX. 57 of our enquiry respecting the structure of the cotton fibre, viz., (b) in regard to its chemical constitution. When the cotton has been gathered and the more volatile portions of the oil evaporated, there remains associated with the cellulose sheath a peculiar wax, which has received the name of cotton wax from Dr. Edward Schunck, F.K.S., who first discovered and investigated its properties. * From the fact that when this wax is perfectly pure it is practically insoluble in alkalies, while it is readily so in alcohol or ether, it has been assumed that the wax is really deposited on the surface of the outer sheath of the fibre ; and when the cotton is subjected to the action of hot liquid in bleaching and other processes, this wax is simply melted and removed mechanically from the surface. When subjected to the action of strong alkalies, the natural oils and fats of the fibre are saponified and, may be collected by afterwards neutralizing the resulting liquid with sulphuric acid. The cotton wax is composed of Carbon 8O38 per cent. Hydrogen 14*51 ,, Oxygen 5-11 100-00 The composition of this wax appears to differ slightly when derived from different kinds of cotton, but the * Memoirs of the Manchester Literary and Philosophical Society, vol. iv., third series, page 95. 58 STRUCTURE OF THE COTTON FIBRE. above is the average derived from the American fibre. The wax fuses at a temperature of 186'8Fah., and solidifies at 179'6Fah. ; while the wax derived from Dhollerah cotton has the same melting point, but does not solidify until it has reached 177'8Fah. Both these waxes bear a similarity to cerosine, a wax prepared from the leaves of the sugar-cane and the Carnauba palm (Corypha cerifera), the composition of which we give to show the difference : Sugar-cane Wax Carnauba Wax. Carbon 81-00 80-36 Hydrogen 14-16 13-07 Oxygen 4-84 6-57 100-00 100-00 Dr. Schunck prepared this cotton wax by boiling 500 Ibs. of Middling Orleans cotton spun into 20's yarn, so as to remove all mechanical impurities, in a strong solution of soda ash for seven-and-a-half hours. The result was a dark brown liquor, which, when treated with sulphuric acid, precipitated a light brown flocculent matter, which settled to the bottom of the vessel, and was separated by filtration. When dried and inspissated, a brittle horn-like mass was obtained, American cotton yielding about 0'48 per cent, of this substance and Dhollerah cotton about 0*337 per cent. I mention this because in repeating these experiments I have found that the quantity of the precipitate obtained varies with the district from which the cotton is obtained, and also from year to year from FATTY ACIDS. 59 the same district ; and the oily wax, therefore, being variable in quantity, will no doubt affect the spinning properties of the cotton in different seasons, as well as its chemical reactions afterwards. Along with this wax there is also a fatty acid, which is white and solid, and which by analysis has been proved to be identical with margaric acid, which is composed of C 34 H 34 4 . There seems reason to believe, however, that this fatty acid is really a mixture of two other fatty acids, probably stearic and palmitic acids, but the quantity obtained from even a large weight of cotton fibre is so small as to prevent their being crystallized out for specific investigation. The largest soluble constituent, however, is pectic acid, a highly complex hydro- carbon; and Dr. Schunck is of opinion that the loss which cotton sustains in weight by bleaching, and which amounts to about five per cent., results from a change in this pectic acid to parapectic acid, or some such other substance, which is derived from the action of the alkalies upon the pectine, and which are soluble in water and not precipitated by the after neutraliza- tion by sulphuric acid. It will appear evident to all, that just in proportion as any cell contents remain within the fibre, they will resist the entrance of any extraneous matter; and as all the juices of growing fibres are more or less un- stable chemical compounds, when compared with the fixed stability and neutrality of the cellulose, into which they ultimately change, when the process of 60 STRUCTURE OF THE COTTON FIBRE. growth and ripening is complete, they will, if any unchanged juices remain within the liber walls, act with more or less energy upon any mordant or dyeing materials with which it may be necessary to impreg- nate the fibres, and interfere more or less with the perfection of the dyeing process. When perfectly ripe, the cotton fibre consists of almost perfectly pure cellulose, a substance which is composed of C 6 H 10 5 , and which possesses little affinity for almost any other substances or reagents except very strong acids or alkalies. The exact composition of cellulose in 100 parts is as follows : Carbon ; 44-444 Hydrogen 6173 Oxygen 49-383 100-000 These numbers are the composition calculated from the formula. The direct results of analysis of different samples yield slightly different numbers, as will be seen below, where analyses by Dr. Gladstone and Professor Pettenkofer yielded the following quantities : Gladstone. Pettenkofer. Carbon 44-37 44-50 Hydrogen 7'24 6-10 Oxygen 48-39 49-40 100-00 100-00 The arrangement of the atoms in the cellulose CELLULOSE MOLECULE. 61 molecule may probably be represented by the follow- ing diagram H H H I I I H-C-C=C=C-C-C-H II II 00 000 II III H H H H H Here we have a central carbon atom uniting the two halves of the carbon chain with double bonds, while the hydrogen and oxygen atoms are united to the other carbon units by single bonds. From this it appears probable that the oxygen and hydrogen atoms are not arranged in the molecule in the form of water, but in the form of hydroxyl, while five of the hydrogen atoms are directly united to the central carbon chain. It seems, indeed, almost impossible, with a due regard to the atomicity of the constituent atoms, to arrange them in any way, within the mole- cule, in which the oxygen and hydrogen shall be associated in the form of water, and it therefore appears that any moisture which is usually found associated with the cellulose, under ordinary con- ditions, is not an integral portion of its molecular structure, but simply mechanically associated, or present as water of crystallization along with mineral impurities, or as a part of the liquid cell contents, or else in some very feeble form of chemical combination along with the cellulose itself as water of hydration. This is an important point, because we must remem- ber that along with the cotton fibre there is always 62 STRUCTURE OF THE COTTON FIBRE. more or less water constantly present. In the new crop cotton this is more abundant than when the bales have been left for some time in a dry ware- house, so that any water which is only mechanically associated has had time to evaporate ; and there is strong reason to suppose that in some instances, both in America and other countries, the fact that water costs little and weighs much is not altogether forgotten. Apart, however, from any addition of water with fraudulent intent, there is always a certain quantity present, which passes off when the cotton is exposed in a loose condition in a room or warehouse at about 60 Fah. This quantity of water varies with different seasons from one to about four per cent, in the new crop, and rather less as the season advances. Above 2 per cent, of moisture however seems to be an excessive quantity even in new crop cotton, and when more than this is present it is either the result of a wet season and the cotton has been packed before drying, or else it has been artificially added. When this has been removed, however, there is still a further quantity which evaporates off when the fibre is subjected to a higher temperature. This amount of moisture may be looked upon as essential and not artificial. It forms, in fact, what is known as water of hydration, which seems to be associated with the fibre, and united to it in a kind of feeble chemical combination, and depends probably upon the same cause as that which enables fibres to attract and retain colouring matter, or absorb gases in large proportions WATEE OF HYDKATION. 63 as compared with their own volume. If this water is removed, by subjecting the fibre to a high tem- perature, it is speedily replaced when the fibre is left in the ordinary condition as regards temperature, and the fibre presents a harsh, wiry feeling, until it is replaced, and looks wild and hairy. In order to test the quantity which we may suppose this water of hydration to represent, I exposed a number of cotton samples for some weeks in a room where the temperature was maintained at a heat of about 60 Fah. Upon subjecting these samples to a temperature of 212, which is the heat of boiling water, I found that they lost weight to the extent of from 5 to 7 per cent; and when they were replaced in the same room for some days they gradually regained all the weight they had lost, showing that the fibre possessed the power of attract- ing moisture from the atmosphere when drier than the surrounding air. This degree of attraction varied, as we might expect, with the hygrometric condition of the air. All practical spinners have experienced this on the large scale when the dry east wind has been replaced by a moist south or south-west wind; and the yarn in the mill, even with the same thermometric temperature, has weighed heavier, showing that it had attracted moisture. In the same way, when wet, damp weather has been succeeded by dry or frosty weather, the yarn has come round lighter to an extent varying from an almost imperceptible quantity up to 5 per cent. When the same samples 64 STRUCTURE OF THE COTTON FIBRE. were subjected to a higher temperature than 212 Fah. a temperature so hot and dry as to only just prevent the fibre from being charred or singed, a further quantity of water was lost, varying in addition to that lost up to 212 Fah. by about 6 to 7 per cent. So that we can make the fibre, from its normal condition at about 60 Fah., if we raise it in an oven to the highest temperature it will stand without burning, lose from 12 to 14 per cent, of its weight. This we may consider the limit of the water of hydration, and when this is all driven off, and the fibre placed in the usual condition, it never, except artificially watered, quite regains what it has lost. About two to three per cent, seems to be due to the drying up of certain cell contents which have not the power of replacing the moisture. It appears, therefore, to me that we must look upon a certain amount of moisture as an essential constituent of the cotton fibre. Some chemists have supposed that this depends entirely upon the tubular or cellular structure of the fibre, so that it is only an instance of capillary attraction; but the fact that if we precipitate the cellulose from its solution in an ammonio-cupric oxide solvent, the amorphous jelly which has no capillary structure also possesses this same property, militates against this view, and seems to indicate that it is really a question of true chemical affinity. When acted upon by strong nitro-sulphuric acid, three of the molecules of hydrogen are replaced by three molecules of nitric peroxide (N0 2 ), forming a GUN COTTOK 65 stable compound called gun cotton, or trinitfo- cellulose, which appears to have the formula C 6 H 7 (N0 2 ) 3 5 . The nature of this change may be represented graphically by something like the follow- ing diagram, which may be compared with the cellulose molecule already given : H = N = H O ll I I I H N-C-C=C=C-C - C-N H I I II I H 000 00 00 II III H H H H H This compound is insoluble in water, alcohol, or ether, and is unaffected by dilute acids or alkalies. Here we have all the bonds of the constituent atoms saturated, just the same as in the cellulose molecule ; only three hydrogen atoms have been replaced by the compound nitrogenous molecules. We must remember, however, that we are quite ignorant of the nature of the force which keeps the atoms in their respective positions, and any other form of arrangement which satisfies the bonds will also fulfil the conditions which we have sought to represent in the diagram. It is, however, extremely probable that the atoms are arranged in some such way within the molecule, and they are not kept in union as was formerly supposed by the general attraction of all the constituent atoms, but by specific attachment to special atoms in the chain. The attraction acts only from atom to atom, and while F 66 STRUCTURE OF THE COTTON FIBRE. the whole system is balanced by the saturation of all the bonds or affinities of the constituent atoms, the conditions of equilibrium are such, that if one link in the chain is broken the whole system is instantly disturbed, and the atoms seek a new combination. Hence the explosive character of gun cotton. When acted upon by caustic soda or potash, there is probably a compound molecule formed, in which a molecule of sodic or potasic oxide forms a part. Dr. Gladstone states that there is such a chemical combination, which will resist the action of alcohol, but breaks up into cellulose and soda or potash when in contact with water; so that it must be exceedingly unstable. Under all ordinary reagents the cellulose remains unchanged, and all the reagents with which it may be impregnated being unaffected by the cellulose itself are left free to act in exactly the same way as they would do if the cellulose was not in contact with them. When acted upon by strong sulphuric acid, cellulose appears to undergo a change in properties without a change in chemi- cal composition. It becomes hard and tough like parchment, and is indeed the artificial parchment of commerce. From recent researches in dyeing it seems not improbable that stable compounds are in some cases formed by certain substances with cellulose, or at any rate they are able to enter into such union with it, as it exists in the ordinary cotton fibre, as to resist the action of water and other solvents in removing them, MINERAL CONSTITUENTS. 67 although until we have much further knowledge it would be presumptuous to state that they are true combinations in the same sense as between acids and alkaline bases. It is quite possible that since under all ordinary circumstances the cotton fibre is never pure cellulose, that much of the power of the fibre to enter into combination with colouring matter arises from the fact that the change from the original juices into cellulose has not been completely effected, and these untransformed and unstable compounds are the acting agents, not the cotton fibre itself. No cotton fibre is indeed ever perfectly pure cellu- lose. There is always found associated along with it, under ordinary conditions, a certain percentage of water, as we have already seen, but this varies with the seasons, and this along with the oil, wax, fatty acids, albuminous matter, and a certain amount of fixed mineral and colouring matter, renders it probable that on the average there is not more than about 87 per cent, of pure cellulose in any American or other cotton. The mineral matter usually consists of phosphates and chlorides of potash, soda, and magnesia; and sul- phates of these bodies in combination with the various organic constituents of the fibres. These mineral constituents were quantitatively examined by Dr. Ure, and he found that in a sample of Sea Island cotton they amounted to very nearly about 1 per cent., and when a portion of the cotton was incinerated the ashes yielded the following results when analysed : 68 STRUCTURE OF THE COTTON FIBRE. Per cent. Carbonate of potassium 44*80 soluble in water. Chloride 9-90 Sulphate 9-30 Phosphate of lime 9 '00 insoluble in water. Carbonate 10-60 Phosphate of magnesia 8 '40 Peroxide of iron 300 Traces of alumina and loss 5-00 100-00 This result was obtained from cotton which had been scutched and carded, and therefore any mechani- cally adhering mineral matter would be removed, but a more recent determination of the composition of the ash has been made where the cotton was. uncleansed, just as it came from the bales. * A portion of twelve different varieties of cotton were taken and burnt to a white ash at as low a temperature as possible. The ash was then collected, mixed, and analysed. After deducting the sand the numbers were Per cent. Carbonate of potassium 33-22 soluble in water. Chloride 10-21 Sulphate 13-02 Carbonate of sodium 3*35 Phosphate of magnesium 8 -73 insoluble in water. Carbonate 7-81 of calcium 20-26 Peroxide of iron , 3-40 100-00 * Sizing and Mildew in Cotton Goods, by Messrs. Davis, Dreyfus, and Holland, page 16. ANALYSIS OF COTTON SAMPLES. 69 The same analysts also conducted a series of experi- ments to determine the amount of sand and mineral matter contained in different classes of cotton. The samples were taken out of bales upon their arrival in Liverpool. The following are the results: Per cent. Sawginned Dharwar 4*16 Dhollerah 6'22 Sea Island 1-25 Peruvian (soft) 1-68 (rough) 1-15 Bengal 3-98 Sawginned Broach 3*14 Oomrawuttee 2 '52 Egyptian (brown) 173 (white) 1-19 Pernam 1-60 American 1-52 It will be seen from these figures that some varieties are very low in ash, such as Sea Island, Kough Peruvian, and white Egyptian; while others of them, such as Dhollerah, Dharwar, Bengal, and Broach con- tain considerable quantities. Some of the latter, especially the Dhollerah, contained large quantities of sand and was very dirty. As a rule it may be taken for granted that an excess of ash much above 1 per cent, arises from the presence of sand and carbonate of lime, which being only mechanical impurities will be removed by the processes through which the fibre is passed in manufacturing it into yarn. Associated along with the cotton fibre there are also small quan- tities of nitrogen, amounting on the average to about 70 STRUCTURE OF THE COTTON FIBRE. 0*0345 per cent., but differing in different varieties of cotton as follows : Nitrogen. American 0-030 per cent. Sea Island 0-034 Bengal 0-039 Rough Peruvian 0-033 Egyptian (white) 0-029 (brown) 0-042 This nitrogen appears to form part of the albuminous matter which was found by Dr. Schunck to be con- tained in the fibre, and it probably arises from the presence of small quantities of the protoplasm, a nitrogenous compound which filled the living cells during the process of growth, and which remained unchanged at the time when the growth was arrested by the picking and ginning of the cotton. In some cases it may also arise from, or be increased by, the existence of small quantities of nitrates associated with the other mineral constituents. We have already seen that Mr. Mercer discovered that strong alkaline solutions above 50 Tw. do not injure but strengthen the cotton fibre ; but if the solution be weak the result is different and the fibre is tendered, especially if at a boiling temperature. This probably arises from the destruction of the outer membrane, and this may account for the fact that all cottons are not alike in this respect, since the amount of oil, wax, and resinous matter on the surface of the fibre, being different in different cottons, enables some to resist the action much longer than others, and ACTION OF ORGANIC ACIDS. 71 remain strong, while other yarn made from different cotton is tendered. Dr. Calvert, of Manchester, in a paper communi- cated to the Chemical Society, was of opinion that certain alkaline salts, such as silicate of soda, had a deleterious action upon cotton fibre, because of the tendency to become decomposed and form carbonate of soda and silicic acid, which acid he thought acted upon the cotton and tendered it ; and in the discus- sion which followed on the paper, while there was a general opinion that the long continued action of free or carbonated alkali did tender the fibre, there was also a belief expressed that the presence of any crystalline matter in the meshes of the fibre tended to cut and disrupt the cell walls, and thus in a purely mechanical way destroy the tenacity of the fibre even apart from any chemical action. A series of researches were made by M. Dollfus at the request of the Industrial Society of Mulhouse, and conclusively proved that most of the organic acids, such as citric, tartaric, and especially oxalic acid, have a weakening effect upon the cellulose and destroy the fibre, especially when the solutions contain above 2 per cent, of the acid and are accompanied by a boiling temperature, and above. In making these experiments the tissues were steeped in the aqueous solution of acid, dried in air, and then subjected to a temperature of 176 Fah., 212 Fah., and 258*8 Fah., at which temperature the fibre was almost entirely broken up. 72 STRUCTURE OF THE COTTON FIBKE. Strong acids like strong alkalies do not act upon the cotton fibre in the way of tendering it, but, as we have already seen in the case of gun cotton, which is produced by the action of strong nitro-sulphuric acid, alter its molecular structure without altering its appearance, strength, or mechanical properties, since it can be spun and woven, as in Von Lenk's gun cotton yarn and braid, and no difference observed except when brought into contact with flame. Weak acids, and especially when at a high temperature, however, have a very energetic action upon the cotton fibre, and destroy its tenacity, rendering it brittle and weak. This is specially the case with the mineral acids, although all acids have this effect more or less. Singular as it may appear, this action seems to be quite as much mechanical as chemical, for if a quantity of cotton fibre be subjected to boiling acid for some time and then dried, it can be rubbed into fine powder, which under the microscope exhibits all the features of mechanical, and scarcely any of chemical disin- tegration, and the powder can be dyed the same as perfect cotton fibre. It seems, indeed, as if the action of the acid was exerted not upon the pure cellulose itself, but upon the various foreign matters which are associated in the fibre wall along with it, and thus the various component cells are separated from each other, the mechanical structure of the fibre walls being broken up, while the chemical character of its constituent cells remains unchanged. This is really the principle upon which the recovery ABSOKPTION OF GASES. 73 of wool from worn-out mixed fabrics is based. The fabric is treated with acid, which is raised to such a temperature that it completely destroys the tenacity of the cotton, while the wool is unchanged in its fibrous nature, and when washed and neutralized can be separated by a mechanical process. The singular combination of chemico-mechanical action which is observed in the behaviour of the cotton fibre with various other substances renders it increasingly im- portant that our knowledge of the subject should be increased, and nowhere is this necessity for further inquiry more clearly seen than in the behaviour of cotton fibre with various gases. The bleaching action of chlorine is well known, and in the case of cotton it seems probable that its action is rendered more energetic by the property which the fibre possesses, similar to that manifested by spongy platinum or bone charcoal, of concentrating a large volume within its substance. Absolutely dry cotton fibre can absorb at the ordinary atmospheric pressure one hundred and fifteen times its own volume of ammonia ; and I found that it can also absorb con- siderable quantities of oxygen gas. Whether the cause is the same in the case of the platinum or charcoal and the cotton fibre, is a point as yet un- determined ; but they all seem in certain cases to possess the power of precipitating metallic oxides from their solutions, and I believe this is a mechanical more than a chemical act, if it is not true that all our chemical changes are really mechanical, only the 74 STKUCTUKE OF THE COTTON FIBKE. masses of matter are so small, and the spaces through, which they act so minute, that we can hardly realize the similarity. The general action of chemical compounds on the cotton fibre really belongs to our third lecture, and it may be sufficient to note that when cotton fibre is steeped in liquid containing any chemical in solution, it is almost universal that a change takes place in the fibre in some way or other, since, especially if an elevated temperature be employed, the fibre so treated almost always deports itself in a different way, with other substances, to what it would have done if it had not been so treated, notwithstanding that washing and other means are employed to render it chemically clean. A large series of experiments were made some years ago by M. Bolley, in which he treated cotton fibre with a number of different reagents, and in all cases he found that the chemical character of the solutions in which the fibre had been immersed was changed, showing that the action of the fibre was not altogether mechanical, or else all parts of the liquid would have been acted upon alike. Even mechanical contact for a short time with the fibre seems sufficient, for it is a frequent experience that the contact of the finger in making a knot in the grey yarn, even although quite clean except the perspiration and moisture of the skin, will cause that part to resist the dye, which will freely fix itself on other parts of the yarn and cause defects in the goods unless properly cleared previous to the dyeing process. DEFECTS IN DYEING. 75 In illustration of this, I may mention that some time ago, I was sent for to look at a number of pieces which were covered all over the surface with small white marks where the thread seemed to have refused the dye. The defects were visible in all shades, but showed more distinctly in slates and blues than in browns and darker shades. They were also almost always associated with a knot in the yarn, or a thicker place, which was the result of the necessary piecing up of a roving either in the card -room or spinning- room. These parts of the yarn, as all who understand spinning well know, will be the places where the fingers of the workpeople will have come into contact with the thread. The dyer was of opinion that some foreign substance, which was not cotton, was mixed with the fibre, and that it resisted the action of the dye which coloured the cotton, and he was all the more assured of this because he had re-dyed some of the pieces and could not cover the faults, although grey cotton thread which had been sewn into the piece as a distinctive mark came up all right. Upon placing some of the undyed fibre under the microscope it was found to be well formed, fully ripe cotton fibre, with well developed tube walls, and I could see no reason why, if the pieces had been properly cleared before dyeing, so as to remove all traces of anything which would prevent the dyeing solution from coming into contact with the fibre, it should not dye as well as any other part of the thread. A number of the grey pieces out of the same lot, and woven at the 76 STRUCTURE OF THE COTTON FIBRE. same time, were accordingly sent to two other dyers, and as these were properly scoured before dyeing, so that every part of the thread was cleaned from any grease contracted in the manufacturing process, the pieces were returned perfectly dyed in every part of the thread. Although comparatively insoluble in nearly all ordinary solvents, the cotton fibre is com- pletely dissolved in concentrated or strong sulphuric acid ; and it was pointed out by Schweitzer that a solution of oxide of copper in ammonia had also this property, and that when the resulting compound was decomposed by the addition of an acid the cellulose is thrown down as an amorphous jelly chemically iden- tical with cellulose. In ether and alcohol the fibre is unchanged, except that the outer membrane is rendered more permeable to fluids after the action of these bodies, probably by the removal of the natural wax which coats the surface ; but if the cotton is acted upon by nitrosulphuric acid in certain propor- tions, so as to produce a form of pyroxyline or gun cotton, in which there is a molecule of nitric peroxide less than in the explosive form, it readily dissolves in a mixture of ether and alcohol, and forms the collodion of commerce used for photographic purposes. Many cottons also contain associated along with them more or less endochrome, which is irregularly distributed in the interior of the fibres. Along with the Egyptian cotton there is always a large amount of this colouring matter, which is present in sufficient quantity to give a decidedly reddish-brown or golden COLOURING MATTER IN COTTON 77 colour to the fibre, and which is soluble in alcohol, but what its exact nature and composition is I have not been able to determine. Dr. Schunck, F.E.S., in the paper before referred to, made a very careful examination of the colouring matter associated with American and East Indian cotton, and found that it was of two kinds, one of which is readily soluble in cold alcohol, and which he called A, and the other, which he named B, soluble in boiling alcohol. These two substances yielded, upon analysis, the following results in 100 parts : A. B. Carbon 58-30 57-77 Hydrogen 6-12 6-05 Nitrogen 6-18 874 Oxygen 29-40 27*44 100-00 100-00 He remarks : "It will be seen that the composition of the substance varied, especially as regards the nitrogen, much more than it ought to have done, supposing it to have been perfectly pure. In con- sequence of the amorphous nature of the product, it is difficult to determine whether the Indian and American cotton contain two distinct colouring matters, both easily soluble in alcohol, and having the same general physical properties, or whether in one or both cases the specimens submitted to analysis, though essentially the same substance, were not chemically pure. It is difficult to obtain, in a state 78 STRUCTURE OF THE COTTON FIBRE. of purity, an uncrystallizable resinous body, having few characteristic properties, and the results arrived at by examining such bodies are seldom satisfactory." " From what has just been stated, it may be inferred that, as regards their chemical properties, these colour- ing matters possess very little interest. It is simply the fact of their being the cause of the yellow or brownish tinge natural to raw cotton which gives them any importance, and makes a knowledge of their properties desirable from a practical point of view. The darker shade of colour seen in the so-called 'nankin' cotton is probably due to a great excess of these colouring matters existing in the fibre. It is certainly not caused by oxide of iron, since the ash of this kind of cotton contains no more iron than that of ordinary kinds, and the colour is for the most part removed by treatment with caustic alkalies." In some samples of very dark coloured Egyptian cotton I have detected distinct traces of iron, some combi- nation of which may be the cause of its specially dark colour. Just, however, in proportion as the action of cotton upon dyes is strictly mechanical will any change in its physical structure render it more or less adapted for dyeing, as the alteration which takes place favours or disfavours its action as an absorber or dialyser, and hence the importance of a knowledge of its physical structure, and the changes which it undergoes in varying seasons, and under different geographical and other conditions. VAKIATION IN EIPEKESS. 79 This really brings us to the second part of our paper, viz. : II. What variations from this type structure are presented to us? (a) In fibres from the same plant and grown at the same time. This part of our subject has already been to some extent anticipated in the remarks which we have already made in regard to the various appearances which are presented by the various members of a lock of cotton, and in which we have pointed out those characteristics of the hair which constitute what we may consider a typical cotton fibre. Unfortunately I have not been able to examine as many specimens as I should have liked, both on account of the limited number of cotton bolls which have come into my possession, and the limited time which has been at my command to pursue these investigations, but I have been astonished to find how wide are the differences even in two contiguous bolls, in regard to the number of perfect fibres and the degree of ripeness to which they have attained. In order to study the growth of the fibre under all its conditions I planted a number of seeds in the greenhouse, and had thus the oppor- tunity of observing the boll and fibre from their first appearance on the tree, although they will probably differ slightly when grown in the open fields from the artificial conditions when under glass. There is no doubt but that the ripening process is really con- tinued in many fibres after the process of picking is 80 STRUCTURE OF THE COTTON FIBRE. completed, and that the drying up of the various juices which are contained in the unripened fibre when severed from the seed by the gin, even after the cotton has been packed in bales, renders it more fit for use in textile fabrics than it would be if taken immediately after it has been plucked, and the mechanical process of ginning which separates the hair from the seed, makes an intimate mixture of the fibres from the various parts of the boll, and this tends to average the degree of maturity and ripeness in the whole mass which is afterwards baled. How great however is the difference in this respect and in the degree of readiness with which the various fibres, and even portions of the same fibre, take up and retain the dyeing matter which is afterwards pre- sented to them, may be readily seen by examining a lock of dyed cotton under a microscope. The wonder will then be, how, out of such a mass of partially dyed fibres, the generally uniform appearance of dyed yarns can possibly be attained. The fact is that very few fibres are perfect in their mechanical structure, and very few are perfectly dyed. We shall, indeed, when we come to the third part of our subject, see how the colouring matter in dyed fibres is only scattered through their length in detached and isolated masses, and that our most solid colours are after all only broad effects obtained by the reflection from the brilliant surfaces of innumerable small masses of colour, whose distances of separation are too small to be detected by the naked eye. STRENGTH OF FIBRES. 81 As a rule, those fibres always appear to be most perfect which, from their position on the boll, have come most under the influence of the sun and air, and those parts of the boll which lie underneath, and have been shaded and enclosed, present the largest number of undeveloped fibres and abnormal growths. It was my intention to have instituted a series of experiments with a view to test the strength of various fibres of different degrees of development and ripeness, but from the impossibility of detaching a sufficient number of fibres of the various kinds to arrive at any numerical results, which could be relied upon, I abandoned the intention, but I have no doubt but that the maximum strength of the fibre, which is after all a very important element in the manufacture of yarn and cloth, depends upon the perfect maturity of the growth. This has been done to a certain extent by Mr. C. O'Neill, F.C.S., who in a valuable paper to the Manchester Philosophical Society detailed a number of experiments in reference to the strength of the fibres from the different classes of cotton. He arranged them as follows : Mean Breaking strain in grains. Sea Island (Edisto) 83-9 Queensland 147-6 Egyptian 127-2 Maranham 107 '1 Bengueld 100-6 Pernambuco 140-2 New Orleans 147*7 Upland 104-5 Surat (Dhollerah) 141-9 (Comptah) 1637 G 82 STRUCTURE OF THE COTTON FIBRE. It appears, therefore, that certain classes of Surat carry the highest weight, and next in order follow American, Australian, Brazilian, and Egyptian, while Sea Island comes last. To make a fair comparison of the relative strength we must compare these breaking strains with the diameter of the fibres, and we shall then see that they follow roughly the same relations, viz., the fibre which carries the highest strain has the largest diameter, and therefore the largest sectional area to resist the breaking. In proportion to the sectional area, however, the Egyptian cotton is rela- tively the strongest of all ; because, while its diameter is only "000,015 or T,Wtl!(Ftf(j f an i ncn larger than the Sea Island fibre, it carries 4 3 '3 grains more, and while it is '000,189 or T.nM.TJW f an i nc h smaller in diameter than Surat it only carries 3 6 '5 grains less, while in proportion it ought to carry considerably less than it does, for, if the tubes were perfectly round and solid, the Surat has very nearly twice the sectional area of the Egyptian fibre which should therefore only carry about 82 grains, whereas it carries 127 grains. These results however can only be taken as approxi- mate, since it is impossible to make a sufficiently large number of experiments upon which to base a thoroughly reliable generalization. It follows, nevertheless, from a very simple mathe- matical law, that the strength of the fibre will vary with the sectional area of the tube walls, and those tubes where the ripening process is complete, and the secondary deposits or thickening of the tube walls, METHOD OF FRACTURE. 83 from whatever cause it may arise, carried on until the central cavity becomes diminished to a mere point, will present the greatest resistance to any force which tends to tear the tube asunder, as well as prevent the creasing of the fibre and collapsing of the walls, which are often seen to be accompanied by a breaking of the cell walls and consequent fracture of the tube. It will frequently have been noticed by all, that if a ribband of paper be taken and stretched perfectly parallel, it will, even if only very thin, carry a con- siderable pressure; but if the pressure is thrown unequally on one side it rends immediately, for the slightest tear in the edge causes it instantly to slit across through to the other side. So with the flattened unripe cotton fibres: the attenuated walls of the tube offer no support to the edge, and rupture is the result of the slightest pressure; while in the fully mature and ripened fibres the thicker and denser walls resist the collapse of the tube, and tend to equalize the strain all round. In breaking a fibre under the microscope it is not easy to see which part gives way first, but from a number of experiments the process usually seems to be of this nature. When subjected to tension the walls have a tendency to collapse, and since no fibre is perfectly round, they always, when under strain, tend to depart more and more from the cylindrical shape. When the flattening process has gone so far as to obliterate the whole of the central opening, the extreme outer structureless pellicle seems to suffer rupture first, and the inner parts of the tube 84 STRUCTURE OF THE COTTON FIBRE. walls seem to slightly extend, and then the whole completely severs. This severing is usually accom- panied by a drawing out of portions of the secondary deposits which remain, after the rupture is complete, in the form of fibrous masses, giving a very ragged edge to the fractured tube. In dyed yarns which have the cellular spaces filled with microscopical crystals, the tendency to rupture seems to be increased by the sharp edges of the crystals penetrating the cell walls, where they are closed in upon the crystals by the extension of the fibre when under strain. When the fibre is fully matured the density of the tube walls seems to be greatest, and the molecules which enter into its com- position are more firmly locked together ; in fact the fibres contain the largest amount of solid matter, and hence they resist the greatest amount of tension. It follows, therefore, that the more fully matured the cotton the more is it fitted for the various uses to which it has afterwards to be put in the manufac- turing process, whether it be mechanical or chemical ; and since this ripeness and maturity depend upon the rain, and sun, and air, and freedom from the ravages of insects or disease which it experiences when upon the plant, it is interesting and important to notice the variation in (b) The fibres from the same plants grown in different years. Unfortunately, this can only be done by careful watching over a long series of years, and can only be EFFECT OF SEASONS ON COTTON. 85 successfully carried out in the places and localities where the cotton is grown ; and hence on this point I can only speak from a general experience and from the analogy which we may naturally suppose to be presented by all vegetable growths. It is a well-known fact that if we examine the rings which are presented by the section of any exogenous or dicotyledonous tree we can tell what kind of seasons there have been during the life-time of the tree. The space between the rings being widest in those seasons where abundance of water and heat has stimulated the development of the woody fibre, whereas in dry seasons, where the growth of the plant has been checked, the distance between the rings is smaller. In the same way a good or bad harvest, either of cereals or fruit, is the resultant of the sum of the rain and sunshine, heat and cold, and other meteorological conditions with which the vegetable life of the country has been favoured, or against which it has had to contend. Cotton is no exception. Some years are distinguished by good and some by bad crops, and as we might naturally suppose, the years when the crop is most abundant are also distinguished by the quality of the cotton being also generally the best, because the same conditions which favoured the production of a large quantity of bloom also favoured the ripening and maturing of the fibres. All who are practically engaged in the manufacture of cotton know that the fibre of one year frequently differs from that of another in many important par- 86 STRUCTURE OF THE COTTON FIBRE. ticufers. During some seasons it is much drier than others, and it also differs to a marked degree in the quantity of natural oil which is associated with the fibre, possibly as a cell content, and this has an un- doubted effect upon the spinning properties which it possesses and the relative strength of the yarn. This natural oil imparts a kindness and suppleness to the fibres in working, and prevents the drying up of the cell walls until they become hard and crack, while its absence imparts a degree of harshness and want of pliability to the fibres, which very naturally inter- feres with the ease with which the fibre can be manufactured into yarn. Nor can we wonder that the effects produced by these changes should also affect the character of the reactions when subjected to any dyeing process, especially when we remember how largely the power of the fibre to absorb the dyeing materials depends upon the maturity of the fibre and the freedom from cell contents in the fibre which would act upon the dyeing solutions, especially in the lighter shades of fancy colours. So that, speaking strictly, the cotton of each season requires a special manipulation, and many of the anomalies which are not unfrequently met with in both the spinning, dyeing, and manufac- turing processes, are really the result of changes which occur in the fibre from one season to another, and which have passed unnoticed, being inherent in the structure of the fibre and far too small to be detected by the naked eye. UNCHANGED JUICES IN FIBRES. 87 The character of the season undoubtedly influences the quantity of perfectly mature and ripe fibre which is contained in the boll, and also the nature of the chemical changes which occur in the cells of which the fibre is composed. When the changes and growth are complete, as in the case of perfectly ripe cotton, all the astringent and acid juices are perfectly trans- formed either into cellulose, sugar, or oil, and are therefore neutral to the various dyeing and other materials with which they are afterwards impregnated in the after processes to which they are subjected ; whereas, when the changes in the juices are incom- plete, unless special precaution is taken in the clearing process preparatory to dyeing, there is apt to be left in the cells a sufficient quantity of astringent or other matter which will certainly interfere with the perfection of the dyeing. One season, some years ago, when very fine Egyptian yarns were being used, and the run was principally upon light and delicate shades, I was called in to more than one arbitration case where individual fibres and masses of fibres had turned black or dark shades in all those colours where salts of iron were used in the dyeing process, and from the appearance of the dark colouring matter in the cell walls of the individual fibres, I was convinced that it arose from the presence of a tannin-like body which was present in the juices of the growing fibre, and which from the want of sun during the growing season had never changed into more neutral compounds, and therefore entered into 88 STRUCTURE OF THE COTTON FIBRE. combination with the iron, producing a kind of ink, with the consequent result of producing serious defects in the goods, which could not be removed out of the yarn before the process of dyeing by the ordi- nary methods of washing or clearing the cotton. The next season, with the same shades and goods, the defect hardly ever occurred, and it had seldom done so the year before. I have also reason to believe that the peculiar kempy structure, about which I have already spoken, is more abundant in some seasons than others, and this structure from its resistance to all dyeing pro- cesses will certainly interfere with the perfection of the goods whenever it attains more than a certain proportion of the whole of the fibres. Another very important matter is uniformity in length of fibre, since upon this, to a very large extent, depends the quantity of waste which will be made in the various stages of manufacture, and the degree of perfection to which the various processes can be carried. All our carding, drawing, and spinning processes depend on an average uniformity in this respect, since the setting of the cards and rollers is necessarily constant for the same cotton. If the length of fibre is very various, and it does not draw out, as the Liverpool brokers say "with a square edge," these processes are all more or less imperfectly performed and irregular, and faulty yarn and cloth is the result. Different seasons present a marked difference in this CLASSIFICATION OF COTTONS. 89 respect, and when, as in bad seasons, in addition to this, the irregularity is further increased by the tender- ness of the staple, which tends to break up under the mechanical actions to which it is subjected, the evils are intensified, and the difficulties of manufacture rendered greater. These differences, arising in cotton grown at the same place in different years, are not however to be confounded with the specific differences in the nature of (c) Fibres grown in different countries. Generally speaking there is a family likeness in all cotton fibres from whatever country they may come, but these general characteristics are modified by the special character of each of the great cotton growing districts. As we have already seen, if we rank them in the order of the length of the staple they may be classified as (1) Sea Islands, including Australian and Australasian cotton ; (2) Egyptian ; (3) Brazilian and South American States; (4) American, from the various parts of the United States, Sea Islands excepted; (5) East Indian, or Surat cotton. In Sea Island cotton we have the most perfect form of the cotton fibre, and for its length of staple, small diameter, general excellence, silkiness, and beautiful gloss, it always commands the highest price, and can be spun into the finest numbers. When examined under the microscope it is easily seen that the general structure of the fibre is of a finer texture than the other cottons, and that there is usually a large pro- portion of mature fibres in a boll. This probably 90 STRUCTURE OF THE COTTON FIBRE. arises from the fact that it is grown under climatic conditions which are peculiarly favorable to the development of all the qualities which are most desirable in cotton, and it is not improbable that with a careful attention to the selection of seed and irriga- tion a great improvement might be made in the general character of cotton fibres; indeed, I have in my possession a specimen of cotton grown far from the Sea Islands, in one of the American States, which rivals in length and silkiness of staple any cotton I have ever seen. The fineness of Sea Island cotton may be illustrated by the fact that it has been spun into counts as high as 2,150 hanks to the pound, so that 1 Ib. of this yarn would extend upwards of 1,000 miles. Egyptian cotton stands next to the Sea Island in possessing all the most desirable qualities, and since the introduction of the combing machine, which enables the irregularities in the fibre to be adjusted by the removal of all which fall below a certain standard, it has been used in the production of many of the finer numbers of yarn, up to indeed about 150's. Egyptian cotton is usually also distinguished by a certain golden or brownish-yellow colour which arises from the presence of an endochrome associated with the cellulose which forms the fibrous sheath. The introduction of American seed into Egypt has however introduced a white variety, which nevertheless does not fully partake of the best qualities of the nature of the Egyptian fibre, but retains many of the charac- SHOKT FIBRES IN COTTON. 91 teristics of the original American cotton. There is always associated, more or less, with Egyptian cotton, a much shorter series of fibres, which are attached to the surface of the seed, forming a sort of undergrowth to the general long fibrous covering, and these short fibres coming off the seed in the process of ginning render the general character of the cotton less clean, and neces- sitate a more careful attention to the cleaning and carding processes in the earlier stages of manufacture than when the American cotton is used. When examined under the microscope these shorter hairs appear to have the characteristics of undeveloped fibre, as though they were stunted in their growth or arrested in the earlier stages of development, and from their possessing little or none of the necessary thick- ness of tube wall to receive or retain dyeing materials they are very apt to produce imperfection in the yarn and goods which are manufactured out of them. This peculiar undergrowth of short hairs and un- developed fibre is not however entirely confined to Egyptian cotton, but occurs more or less in all varieties, and is, as we have already seen, one of the causes which lead to what is technically called "neps" on the surface of the finished yarn. There appears to be a considerable difference in this respect, both in different years, and even in different lots of cotton in the same year, and it may possibly arise from the peculiarity of the Egyptian climate where rain never falls, and the irrigation is entirely dependent on the height of the Nile, and which undoubtedly renders 92 STRUCTURE OF THE COTTON FIBRE Egyptian cotton as a rule more uncertain in its character than most other cottons. Notwithstanding these disadvantages, however, the Egyptian cotton occupies a very important position as a raw material, as in proportion to its diameter it is relatively stronger than American cotton, and possesses a silkiness of surface and suppleness of fibre, which enables it to be used for the large mass of single yarns which lie beyond the range of American cotton, but which must be produced at a price much less than could be pos- sible if Sea Island cotton had to be used. Similar counts of yarn made out of American and Egyptian cotton respectively, when examined under the micro- scope, seem to differ considerably in their character- istics arising from the different nature of the fibres. The Egyptian cotton lies closer, the fibres the'mselves seeming capable of turning a sharper angle with less disturbance of the molecular structure of the fibre and less tendency to rupture, and on account of the less diameter of the fibres the threads, of the same counts, are finer with the same twist in, that is to say, they are less in diameter and yet possess an equal weight of material, and a larger number of fibres in the cross section of the thread. The regularity in the diameter of the individual fibres of fully ripe Egyptian cotton is also greater than in any other class of cotton, and this alone is a very great element of strength, because the fibres are more evenly distributed in the yarn, and the ability to carry strain therefore more uniform. The existence ACTION OF LIGHT AND HEAT. 93 of the endochrome in the fibre walls of the Egyptian cotton, which gives it the brownish-golden colour, renders it less fitted for mixing along with other classes of cotton ; and I have found that this colouring matter is also acted upon by light, and moist heat, especially when the latter is above the boiling point, a sample of Egyptian cotton becoming darker when exposed to sunlight, and also when subjected to the steaming process before doubling. This cause also renders Egyptian yarns more liable to variation in colour with different seasons of the same year, and also from year to year, and oftentimes necessitates a bleaching process before they can be trusted to receive the lighter shades of delicate colours. All these points we shall afterwards see to be matters of considerable importance when we come to our next lecture. Brazilian or Peruvian cotton fibre, which stands next to Egyptian, forms a convenient connecting link between it and American. It possesses in some respects many of the qualities of the former, but it does not possess the same regularity, especially in the diameter of the fibre. Some classes of this cotton, such as rough Peruvian, have a harsh wiry feeling, and while possessing a long staple have a strong coarse tube, with well-defined cell walls. Whether it is from the nature of the conditions under which it is grown, or the variability of the climate, it seems to be sub- ject to considerable variations from one year to another, and also to contain from some districts con- siderable quantities of leaf and broken seed. Too great 94 STRUCTURE OF THE COTTON FIBRE. stress cannot be laid upon the necessity of care and attention in the picking and ginning processes, which are conducted in the countries where the cotton is grown, as the breaking-up of the fibre, or the seeds to which the fibre is attached, render the cotton far less suitable for the high class of manipulative workman- ship which is now demanded, and when these disad- vantages are added to the necessary variation which arises from bad seasons and other causes, they present difficulties to the application of the fibre to technical purposes which can scarcely be overcome. Some of the Pernam and Ceara cottons, however, take a high position, both in the perfection of the staple and the general regularity of the fibre, and are largely used, either by themselves, or along with American, in the production of yarns, where the American staple is too short for the counts when used by itself, and Egyptian too dear in the whiter varieties, and too highly coloured in the lower qualities to render it available. American cotton, such as is grown in the fertile regions forming the south portion of the United States, is however the typical cotton fibre, the "King cotton" about which we hear so much. Its general uniformity, the skill with which it is cultivated, gathered, and ginned, and the excellence of its spinning qualities, within the range of counts where by far the largest quantity of yarn is required, render it pre-eminently "the cotton fibre." It is subject to variations from year to year, both in regularity of staple and other conditions, but in a country which AMERICAN COTTON. 95 stretches from the New England States to the Gulf of Mexico, and from the stormy shores of the Atlantic ocean, westward, to the Kocky Mountains and the more peaceful waters of the Pacific Main, such a thing as a general failure in the crop has scarcely ever been known. Year by year, since the disastrous civil war, the quantity of cotton raised in the United States has continually increased, and under the benign influences of peace it is to this great region that the eyes of the world are turned, as the great garden from which must come the raw material to clothe the teeming millions of its population. Only a change in the restrictive tariffs of the United States is required to give its mighty energies free course, and enable the millions which will one day people the valley of the Mississippi and its tributaries, to receive the countless wealth which the nations will pour into their lap, in exchange for this "Snowy wool." When examined under the microscope, as compared with Egyptian cotton, its pure white colour and trans- parent character strike the eye at once, as do also the coarser nature of the fibre, and less general uni- formity in diameter. When examined in the yarn these characteristics give the thread a more loose and less solid character, as though the general structure of the fibres was more rigid and less yielding than Egyptian, and in the fracture of the fibres themselves the elasticity seems to be less. In its general charac- ter, however, American cotton may be taken as the representative of the typical cotton fibre. Its usual 96 STRUCTURE OF THE COTTON FIBRE. soundness of staple, and freedom of the cellulose, in the fibres, from both mechanical and chemical impuri- ties, render it eminently fitted for the production, within a certain range, of all classes of yarns and goods when colour, and regularity, and good wearing qualities are desirable. It is pre-eminently the cotton out of which the vast class of cotton goods for domes- tic use are made, and it passes through the various processes necessary in its conversion from the raw state into the finished article, whether plain or coloured, with less trouble and difficulty than any other kind. In a word, it is the standard by which other cottons are compared, and as a general thing the price of American cotton rules the markets of the world. Indian or Surat cotton stands last in the order of cottons. It possesses the shortest average staple, and is the coarsest in its nature, although there are some classes of Surat which have a comparatively fine staple, and reach their highest development in what are known as Berars and the Hingunghat of the central provinces. The fibres under the microscope usually present the appearance of well-marked twisted tubes, but they seem to be more frequently, so far as my observations go, variable in the thickness of the tube walls, and in the tendency to produce solid instead of hollow fibres. The production of this class of cotton received a great stimulus during the scarcity of American occasioned by the civil war, but since that time they have not maintained the same position. The short- VARIETIES OF COTTON. 97 ness of the staple, and the large amount of fine sand and other mechanical impurities associated with them, render them relatively more wasteful in working than American, and less fitted for the requirements of manufacturers. The variability of Indian climate in regard to rain-fall and drought, makes them as a rule less reliable in general character than American, but in favourable seasons, this cotton, either by itself for low counts, or mixed along with American, possesses good spinning properties, and if properly attended to during the early stages of its growth and in the ginning and packing processes, there is no difficulty with suitable machinery in making first-class goods from it. I cannot sit down, however, without calling your attention to the following table, which contains a list of the specific varieties of the four great classes of cotton which we have just considered. This table gives the special names of the various cottons ordi- narily used for manufacturing purposes, and for which prices are daily quoted in Liverpool; and I have appended to them in other columns the species of cotton seed from which they are usually grown, the district where they are cultivated, and the average length of the longest staples, as well as the counts into which they are ordinarily spun. These can only, however, be taken as generally correct, because within recent years non-indigenous cotton seed has been used in all countries, with a view to improve the staple or general quality of the fibre, and in manu- H 98 STRUCTURE OF THE COTTON FIBRE. facturing there have many experiments been tried for the purpose of obtaining higher counts of yarn from the lower qualities of cotton, a process which has been rendered easier by the increased improve- ment in the preparing and spinning machinery. In addition to this, many special qualities of yarn are being made at the present time, and these of course cannot be taken into account. It will be noticed in looking at the relative length of the staple in American and Indian cotton, that the possibility of spinning into finer counts depends upon the fineness and suppleness of the fibre as well as upon the length. The various qualities are arranged in the order of the prices which they usually realize, the better qualities and higher-priced cottons usually standing first in their respective classes; and this table may be profitably compared with the price list issued daily by the Liverpool Cotton Brokers' Association. The improvements in cultivation, and the careful attention which in certain districts has been paid to a proper crossing of the native with foreign seed, so as to secure a plant which will thrive well in the climate and yet possess more valuable properties than the native cotton, have greatly increased the value of many of these varieties. The number might have been very much increased, but I think this will serve as a general guide in selecting the cotton for any special purpose : CLASSES OF COTTON. 99 TABLE OF THE VARIOUS CLASSES OF COTTON. Name. District where grown. Species of Cotton. Average Length of Staple in inches. Counts for which it is generally used. SEA ISLANDS. Sea Island Sea Islands on Gossypium Bar- 2'20 Florida Sea Island... Coast of Florida and Georgia Florida, Mainland badense Do 1'95 3 | ^3 w Fiii .. ) ^o ii Polynesian Islands Do 1'88 Tahiti .. ) 8^ La Guayran Venezuela Gossypium Hir- 175 M & a Peruvian Coast of Peru ... sutum Gossypium Peru- 1'50 J* Australian Queensland .... vianum Gossypium Bar- 1'65 ^ badense EGYPTIAN. Gallini Egyptian ... Brown Messefich, &c. ... Za^asi 01 Man su- Gossypium Bar- badense Gossypium Her- 1-50 1'40 upto200's White rah, Behara, &c. Ziftah, &c baceum Gossypium Hir- 1'25 uptoSO's Smyrna Levant and Greek sutum, & Peru- vianum Gossypium Her- 1*24 uptoSO's Islands baceum BRAZILIAN. Maranham Coast of Brazil... Gossypium Peru- 1*15 Bahia, Aracaju, &c.. Pernam &c San Salvador Pernambuco vian um Do Do. 1-25 1'35 1 Q oj Ceara Aracata &c North Coast of Do 1'15 ts 5> o Maceo and Paraiba Brazil Eastern Coast oJ Do 1'20 S-2 2^ Rio Grande Brazil South part ol Do 1'30 '^ J West Indian Brazil West Indian Do 1'30 ^"o Haytien Islands St. Domingo Do 1'30 ^ "^ La Guayran Peruvian Rough... ^ Venezuela Peru Do Do 1-30 j 1-30 f Smooth ) ( 1-35 100 STRUCTURE OF THE COTTON FIBRE. TABLE OF THE VARIOUS CLASSES OF COTTON Continued. Name. District where grown. Species of Cotton. Average Length of Staple in inches. Counts for which it is generally used. AMERICAN. Upland Georgia and South Gossypium Hir- I'OO ^11* Mobile Carolina Alabama and sutum Do 1'05 j* ftl o fco"^ 10 ro *^ Texas adjacent States State of Texas Do 0'95 o 2 ill Orleans Mississippi and Do. I'lO 5 "s C3 2 Louisiana r-5 0> PQ or the 19tn band on Nobart's test-plate, where the lines are 112,000 to the linear inch, and that with the best instruments and the best eyes we soon get beyond the practical limit of vision when we exceed these dimensions. This probable limit for ordinary vision is not smaller than something like the Tsij.wmj^ 1 - f a linear inch, although with an educated eye and proper illumination two portions of an object separated by a distance of i-sr^Tmi^h of an inch can be seen, and this is enormously larger than the probable diameter of fluid molecules, and even many solids when precipitated from their solutions by chemical action; and it does not therefore follow that there are no openings through this outward cellulose layer because we cannot detect them by the eye. We shall afterwards see that there is strong reason to suppose that in the case of certain colouring matters there is an important part played in their fixation on the fibre by the power which the cellulose walls of the fibre possess of acting the part of a septem or dialyser, and thus permitting the passage of fluids into the inner layers of the cell wall, while we shall also see that there are many cases where the fixation of the colour really depends upon a real chemical affinity, or cohesion between the fibre 158 STRUCTURE OF THE COTTON FIBRE. and the colouring matter, quite independent of its mechanical structure. We must remember that all our dyeing processes are after all only a method of giving a new reflecting surface to the body to be coloured. We have already seen that the lustre of cotton depends upon the reflection of light from the plane surfaces of the collapsed tubes ; and whenever these plane surfaces are broken up or wrinkled, either by over ginning or scutching, or carding, the light is dispersed in every direction, instead of being reflected in a sheet to the eye like light from the surface of still water, and the fibre looks dull and not silvery. There is also a great difference in the transparency of the fibres of different cottons, which will easily be seen when examined with polarized light, and this difference I have found has a remarkable effect upon the power of the fibre to receive bright colours in dyeing. Part of the lustre is always due to internal reflection. No body is really coloured in itself, and the colour which it presents is only the total result produced on the retina of the eye by the rays which are reflected, as compared with those which are absorbed or trans- mitted. When coloured bodies, or rather bodies which appear coloured, when viewed under ordinary light, are seen by the rays falling from a monochromatic source, all distinctive colour is absent. This may be easily proved by viewing a box of various shades and colours of silk ribbon, or a pattern-book of bright wall-papers, by the rays derived from an alcohol THEORY OF DYEING. 159 flame impregnated with sodium, when it will be found impossible to tell any colour from the other, however distinct, under ordinary sunlight all colours only appearing as various shades of a yellowish-grey. To dye the surface of a fibre or a yarn is therefore simply the production of such a molecular condition as will return certain luminous wave lengths and suppress or destroy others, and this may be accomplished in a variety of ways; but since permanence of colour is 'also necessary, these methods are chiefly directed to the production of the reflecting surface in the sub- stance of the fibre, so as to prevent its removal by mechanical means such as washing or brushing. The rationale, or theory why and how, this desired surface is obtained by what we ordinarily call the fixation of colour upon various fibres, is a matter of dispute and doubt even to the greatest chemical authorities at the present time. Some suppose that between the colouring matter and the fibre there is a true chemical combination, and that the change occurs in equivalent proportions, just the same as when any other coloured chemical compound, such as plumbic iodide, is formed; while others believe that the com- bination arises from a special force in which the usual equivalent proportions are not obtained, but modified by the catalictic action of the fibre. Others are of opinion that chemical action has little to do with the matter, and that the colours are fixed upon the surface of the fibre by molecular attraction alone, while some again think that the action is altogether mechanical, 160 STRUCTURE OF THE COTTON FIBRE. and that the colouring matter is absorbed into the pores and cells of the fibre, and held there simply as a substance might be enclosed in a glass bottle. No doubt strong reasons can be urged in favour of all these views, and the application of them depends much upon the nature of the fibre and the class of dyeing material used. My own experiments have led me strongly to believe that in wool and silk there is an affinity in the fibre for certain classes of colouring matter which is really a true chemical combination, and the more complicated chemical composition of these fibres, as compared with cotton, renders this extremely probable, as well as the generally acknow- ledged fact that colours are faster or more difficult to remove from wool and silk than cotton, while indigo, whose deposition within the fibre, from its soluble condition by the absorption of oxygen, is faster upon cotton than either wool or silk, seems to point to a more mechanical theory. The chemically inert nature of pure cellulose appears to me to strongly favour the purely mechanical theory of Crum in the case of cotton, and we shall speak again of this further on; while the fact that there often remains in many of the fibres of every cotton boll a considerably large quantity of inspissated cell contents, which do produce, as we have already seen, a chemical action in the case of certain reagents, also furnish a strong reason why along with the mechanical there may be also a chemical action. This belief is also further strengthened by the fact which COLOURING MATTER IN FIBRE. 161 we have already mentioned, that cellulose may be precipitated in an unchanged state chemically from the cupra-ammonium solvent discovered by Schweitzer, and that this amorphous gelatinous cellulose can be mordanted and dyed almost in the same way as the true cellular cotton. A microscopical examination of this dyed amorphous mass, however, seems to me clearly to indicate that there is a great difference in the method in which the colour is associated with this jelly and with the cotton fibre, as in the one it is diffused through the whole mass in such a manner that it is equally coloured in every part, while in the cotton fibre it is always more or less cloudy or uuuniform, and resolvable into flakes with a sufficiently high microscopical power. I am of opinion that if the union between the cotton fibre and the colouring matter was purely chemical, we should as a rule find the colour more deeply seated in the texture of the fibre, as the power of chemical affinity is far more tremendous than that of mere mechanical action, and I have been specially struck with the fact how very small a depth the colours usually penetrate into the substance of the cell walls, which I attribute to the fact that as a rule the fibres are not thoroughly cleansed of their gum and cell contents, and these hinder the mechanical action of the cell walls by affording resistance to the entrance of any fluid or dyestuff. M. Bolley, who worked at this question, was struck with the same thing, for he remarks, "the substance of the cotton hair, that is the cell wall, was M 162 STRUCTURE OF THE COTTON FIBRE. not at all coloured in cotton dyed with indigo, Turkey red, madder pink or purple, chrome yellow, catechu brown, iron buff, or iron black, " and he further remarks that, except with fibre dyed with murexide, very little colour was ever present in the interior of the cell itself. Notwithstanding this, it nevertheless seems that the chemical nature of the fibre has a con- siderable influence in determining the power which it possesses of attracting and retaining colouring matter, which in many cases seems to be very slightly influenced by the peculiar physical structure of the fibre. A series of valuable experiments on this important question were made by M. Kuhlmann,* in which he first acted upon the fibre by nitric and nitro- sulphuric acids, so as to induce a combination of the elements of the nitric acid with the fibrous matter. We must, however, remember that the nitro- cellulose compounds produced are more unstable than the original cellulose itself, and that true substitution compounds may be formed with them which were not possible in the unchanged fibre; and that many animal and vegetable colouring matters may have the power to enter into union with substances which are nearly allied to them in nature, and that provided they are simply able to come into mutual contact in any way, may enter into union in a manner quite independent of the mere mechanical structure of the matter which is immersed in the fluid dye. The more complicated chemical nature of animal fibres favors * Comptes Kendus de 1'Acad., xlii., page 373 ; xliii., page 900. GENERAL THEORY OF DYEING. 163 this action with all the non-mineral colours, while at the same time it renders them less fitted to receive the mineral colours. It is also well known that mineral colours are, as a rule, much better adapted for dyeing cotton than wool, where indeed Prussian blue is almost the only mineral dye used, while in the case of cotton the chemical inertness of the fibre itself favors the reac- tions occurring in the production of mineral colours, and. renders them from their crystalline character easily fixed in the meshes of the cell plexus. Perhaps the best general theory of dyeing is that advanced by the French chemist M. Chevreul, who has given a life- long attention to the subject, and who believes that the matter which colours fibre is fixed in the fibre in three different ways. (1) By chemical affinity. (2) By simple mixture with the fibres. (3) By being in both states at once. By the latter statement he does not mean that the same matter is in both states at once, but that there are cases when the colour of the fibre is partly due to the union of the colouring matter with the fibre, and partly to the presence of a quantity of the same colouring matter in a state of mechanical mixture with the material forming the cells. Probably no general theory which will include all cases and fibres can be framed until we have a much wider knowledge derived from experimental research, which alone can aid us in any extended generalization. 164 STRUCTURE OF THE COTTON FIBRE. It is quite clear, however, that before any colouring matter can be introduced into any fibre, so as per- manently to stain it other than by mere surface colouration, we must have a method of introducing it into the interior of the fibre. Almost all dyeing is accomplished by a wet process, in which the colouring matter is in a state of solution. Some have supposed, in the case of cotton fibres, that absorption into the interior is by capilliary action, the liquid entering by the broken ends of the fibre ; but I found that in fully ripe cotton, even when the liquid was presented to the sides of a fibre alone, it passes into the interior of the tube, swelling out the portion which had absorbed the moisture, showing that a real liquid transfusion had taken place; and this was specially seen when the fibre was mordanted with basic muriate of alumina and dyed in madder. Mr. Walter Crum, F.K.S., in a paper which we have already mentioned, adopted the idea that in the dyeing of the cotton fibre the action was purely mechanical, so far as the fibre itself was concerned, and that the reactions which occurred within the fibre were quite unaffected by the chemical composition of the cotton, which simply served as a containing vessel, as inert as a glass tube, but that the peculiar structure of this fibre enabled it to take in liquids which contained colouring matter in a feeble combination with the solvent liquor, and retain that matter when the colouring matter was either removed by dyeing or precipitated by a reagent. He believed that the energy with which this absor- CKUM'S EXPERIMENTS. 165 bent action is exercised depends upon the smallness of the capillary cavities; and in the case of the thin laminae which form the thickness of the cotton tube when suitably prepared, this energy is very great so great, indeed, that it almost passes belief. Mr. Crum says: " Whether the mordant be applied to a piece of calico in the fluid state, or made nearly solid with an amylaceous or other thickening substance, it finds no difficulty in traversing the whole fibre." He further adds : " I have examined threads which have been soaked with a solution of acetate of alumina altogether fluid, and compared them with other threads which had been printed with the same solution made into a thick mucilage with gum arabic, and with others again made into a paste with flour of wheat, so thick that when applied to one side of a piece of bleached calico it did not pass through to the other side ; and on examining transverse sections of dyed specimens of these fibres, I found that such of them as had been reached by the mordant were in all cases equally penetrated. The white centre was always due to a want of dyestuff. I am glad to be able to establish this fact, an apparent impossibility, which has been a stumbling-block to several of my friends. It is difficult, no doubt, without direct examination, to conceive of a -capillary power so great, or that a solution, rendered so tenacious as to require consider- able force to drive it through an opening of an inch in diameter, should be able, without any pressure at all, to pass into the interior of the cotton fibre, the 166 STRUCTURE OF THE COTTON FIBRE. pores of which cannot be detected by the most powerful microscopes. "* The investigation of this peculiar property of fluids to diffuse through a membranous film or septem formed a new era in our knowledge of the probable action of dyeing materials upon cotton fibres. Pro- fessor Graham, to whom we are largely indebted for these important discoveries in dialysis, found that solution of certain bodies pass through membranes with considerable facility, while others pass through very slowly. Most bodies which are of a crystalline character, such as metallic salts and organic sub- stances, such as sugar, morphia, and oxalic acid, pass through readily, and to these he gave the name of crystalloids ; while bodies devoid of crystalline power, such as gums, gelatine, albumen, and many soluble oxides, which are in an uncrystallizable condition, such as hydrated soluble silicic acid, soluble sesqui- oxide of iron, soluble alumina, and other similar compounds, pass through very slowly, and were termed by him "colloids." The most singular part of his discovery was, that of all substances, parchment paper made the most efficient dialysing septem or membrane. We have already seen that this substance is really pure cellulose, the same exactly as our cotton fibre, except that its mechanical texture has been modified and strengthened by the action of strong sulphuric acid, which has increased its density without altering * "Chemical Journal." Vol. i. New Series, page 409. RELATION OF DYESTUFF TO FIBRE. 167 its chemical constitution. This probably arises from the shrinking in of the laminae of the tube walls, which diminishes their distance and renders their capillary action greater. Through the kindness of my friend Dr. Miller, of London, I have had the good fortune to have in my possession for some time the identical slides of dyed cotton fibres which were prepared by Mr. Crum, and upon the examination of which he formed his theory; and I can bear testimony to the great faithfulness with which the illustrations to his paper are given, and in many cases I believe his deductions are war- ranted by the facts ; but certainly all the reactions between cotton and colouring matter are not purely mechanical, because if they were it is quite clear that its behaviour to all colouring matter in the same mechanical condition would be the same, and experi- ments prove that this is not the case. The various substances used to impart colouring matter to fibres are almost as numerous as the methods employed to fix them on to or into the fibre, and they are derived from both the animal, vegetable, and mineral king- doms. We have already seen that as a rule any dye is more difficult to fix upon cotton than upon either silk or wool, and that a larger number of substances can be used in dyeing the two latter than the former. They also take the dye much more readily, and some dyes, which are readily soluble in water and of great tinctorial power, such as the aniline colours, can be fixed on to either wool or silk by simply bringing the 168 STRUCTURE OF THE COTTON FIBRE. fibres into connection with the liquid containing the colouring matter. So great is the affinity indeed that the fibres will absorb all the dyestuff out of the solvent and leave the liquid quite clear, while the fibres are permanently dyed. The unprepared cotton fibre does not possess this power in the case of the aniline dyes, which only stain the cotton without permanently charging it with colour, since the dye can be removed by the simple mechanical operation of washing. This is not, however, the case with all colours, since there are some with which when we have nothing present except the fibre and the colouring matter a permanent union is obtained. If the action of the cotton fibre was purely mechanical this would not be the case, because we may suppose all bodies which are coloured in themselves to be, even when in a state of solution, more or less as bodies in an exceed- ingly fine state of division, and there is no reason why the mechanical action excited upon each should not be the same, unless we suppose the solvent to differ in its affinity in regard to the various colouring matters, and thus require more or less power on the part of the fibre to separate it from the solvent, or else that the molecular structure of the colouring matter is in some cases such that it cannot pass through the small openings in the outer layer of the fibre. In relation to the fibres of cotton, we may look upon all dyeing substances as of three kinds (1) Those which are coloured in themselves, and ANALYSIS OF DYEING PEOCESSES. 169 which we may term simple dyes, having a direct affinity for the fibre without the intervention of a mordant. (2) Those which are true chemical precipitates formed within the fibre walls, in which the action of the fibre seems to be only mechanical, and does not undergo any change in itself. (3) Those where a mordant is necessary, and the colour is produced not by the simple union of the colouring matter with the fibre, but by the action of various reagents upon the mordant, which unites with the fibre and thus fixes the colour. It is not possible to draw a sharp line of demarca- tion between these three classes of action, because in the relationship of various colouring matters to the fibres they shade into one another, and there are many instances in which the difference is really only one of degree. We may, however, select typical examples in which the widest differences are shown. The first of these classes of dyeing material where we have a direct affinity between the colouring matter and the fibre itself, without the intervention of any mordant or other fixing agent, may be well illustrated by the process of dyeing turmeric, or annatto yellow, or indigo blue. In the case of the turmeric yellow we have the colouring matter simply dissolved in hot water, and when the cotton fibre is immersed in the decoction it speedily acquires a bright yellow colour, which is rendered as permanent as the colour will permit by 170 STRUCTURE OF THE COTTON FIBRE. simply drying the yarn. Here we have evidently the colouring matter held in a very feeble state of com- bination with the solvent water so feeble that we may almost consider it in mechanical suspension in the liquid along with which it passes into the cellular walls of the fibre, and when the solvent water is dried up the colouring matter remains entangled in the cell walls which absorbed it, and which have evidently entered into some sort of chemical union with it, since the colouring matter can no longer be again separated from the fibre by the application of water, showing that a real change has taken place in its nature, since it readily dissolved in water before. In addition to this, there is an aggregation of the colouring matter within the cellulose walls, as though the fibre possessed the power of concentrating the colour, so that the fibre evidently attracts a larger quantity of colouring matter than water within itself, and when taken out of the liquor leaves the fluid considerably less coloured than the fibre which has been immersed in it. In making these experiments I was par- ticularly struck with the fact that when considered in relation to time, the action of the fibre upon the colouring matter was much more rapid during the first intervals than as the operation proceeded as though as the affinities of the fibre were saturated the action of attraction and fixation became slower and slower as the depth of colour increased. When viewed under the microscope with transmitted light, the irregular distribution of the colouring matter will be Plate VII 450 DIAMETERS Cotton Fibres, dyed Turmeric Yellow TUKMERIC YELLOW. 171 distinctly seen, the colour lying in detached patches and masses in the cellulose walls, which seem very unequal in their power to retain it. This will be readily under- stood by reference to Plate VII., which illustrates cotton fibres dyed turmeric yellow and magnified about four hundred and fifty diameters. The whole cell walls are more or less coloured, as is more distinctly seen when the fibres are viewed with reflected light; but after all the colouring matter is very irregularly distributed, and in some places, as where we have an immature or kempy fibre figured on the right, there seems to be none whatever present. This may be termed the very simplest of dyeing processes, being merely the absorption of a colouring matter into the tube walls and leaving a deposit within attached to the fibre by some sort of attraction or combination, which has changed its character from a soluble into an insoluble form. As might be expected in this case, the unripe cotton and immature or malformed fibres resist any dyeing action, because they are not capable of per- mitting the transfusing action within the epidermic layer; and from the nature of the dyestuff, which is only colouring matter in a very fine state of division, a deposit on the outer surface of the fibre which in most cases assists the colour within the outer sheath is almost entirely removed by the process of washing. Bolley, Crum, and other observers think that the power which the cotton fibre possesses to absorb and precipitate from solution colouring matter arises from 172 STRUCTURE OF THE COTTON FIBRE. the same cause which enables finely divided charcoal or other mineral and metallic matter, such as spongy platinum, to precipitate oxides from their solutions or concentrate large volumes of gas within the molecular interstices ; but I am inclined to think that, with the exception of indigo dyeing, this law does not come into operation, because when I have examined sections of fibre dyed turmeric yellow, I have found that while the solid substance of the fibre wall is all more or less dyed yellow, with a pretty uniform tint, the larger and deeper masses of colour are much more irregularly distributed in the fibre walls than they would be if their absorption and aggregation depended upon a general law like this, unless it so happens that the foreign matter, such as wax, oil, and cell contents, interfere with the proper action of the cellulose layers. I was in the hope that an examination of fibres dyed indigo might throw some light upon this sub- ject, because in the production of this dye one of the reagents is gaseous, and therefore in a much finer state of division than any merely mechanically suspended or feebly united colouring matter can possibly be. When the colouring matter is insoluble in water, it is necessary to make such a solution of the coloured substance as will enable it to pass through the cellu- lose wall, and be there precipitated in an insoluble form by the application of some other solution or reagent. In the case of indigo, this reagent is a gas. Indigo blue, which is one of the most permanent of INDIGO BLUE. 173 vegetable colouring matters, is quite insoluble in water, but when in a very fine state of division, and in the presence of lime, water, and ferric sulphate, the indigo undergoes a chemical change by the removal of oxygen, which renders it colourless and soluble. In this condition it is readily absorbed through the cellular membrane and conveyed into the interior of the fibre, and when the fibres are exposed to the action of the air the oxygen is restored and the indigo thrown down within the fibre in an insoluble con- dition. The action exerted upon the solution of indigo seems 'to be, however, more than the mere interpenetration of the cellular tissue, as though the dialysing action of the fibre tends to accumulate the indigo within the cell walls in quantity almost pro- portionate to the time which it is in operation, so that if there be a sufficient quantity of the cotton, it will extract all the indigo from the solution. In this respect this cumulative action is similar to that of the fibre upon the turmeric solution, except that the "white indigo," as it is called, is not coloured and visible to the eye, although when dried before exposure to oxygen it seems to be attached to the fibre in its yellow insoluble state. In our last lecture we saw the power which cotton possessed of concentrating ammonia and oxygen in its pores, and which seems to arise from a similar cause, and this power is enormously increased when, as in the case where cotton fibre has been impregnated with white indigo, there is a chemical affinity between 174 STRUCTURE OF THE COTTON FIBRE. the substance with which the fibre is saturated and the surrounding gas. I am quite willing to admit, however, that this phenomena of gaseous absorption is at present not explainable on any rational principle, either in the case of the charcoal or the cotton fibre, and further experiments are necessary to establish the identity of the causes before we can correctly assume that they are the same. In the dyed state, when viewed under the micro- scope, the cloudy deposit of indigo is clearly seen irregularly distributed through the meshes of the fibre, in many cases penetrating into the central cavity, and forming dark, almost black masses where it is accumulated in the largest quantities. The fine state of division of the colouring matter, and its non- crystalline character, render it less liable to disturbance from the flexure of the fibres than many other dyes, and its perfect insolubility in water permits a considerable amount of surface colouration, which, when viewed by reflected light, causes the fibre to appear much more evenly dyed than when transmitted light is employed. Indeed, this surface colouration is always more or less visible in all fibres which are dyed in insoluble colouring matter, or which are not subjected to severe after-treatment, so as to remove all dyestuff which is only mechanically attached ; and this usually masks many of the defects which would otherwise arise from imperfect formation in the fibres. The colouring matter accumulating in the creases and on the wrinkled and broken surface Plate 450 DIAMETERS. Cotton Fibres dj/ed Indigo Blue IMPROVEMENT IN DYEING. 175 of the collapsed tubes, or in the ridges and furrows occasioned by the hollows of the twisted fibres, forms a coloured reflecting surface, to which the solid and even appearance of this dye is largely due. This will be clearly seen from an examination of Plate VIII., where we have a representation of cotton fibres dyed indigo, which gives us a much better idea of their appearance than any description which could be written. A careful examination of the best dyed fibres, however, seems to indicate that we are still far off the standard of perfect dyeing, and it appears to me that we are much more advanced in the mechanical than the chemical treatment of the raw material. This probably arises from the fact that the general princi- ples of mechanical manipulation are better understood than the obscure reactions upon which our dyeing of the fibres depends, and one of the directions in which we are to look for increased perfection in our finished goods must be in the determination of the means which can be employed in the preliminary preparation of the fibre, so as to enable it better to perform its function as a dialyser, and thus absorb a larger amount of colouring matter and distribute it more evenly. It will, however, be easily seen that we can never obtain this action in fibres which are not possessed of the necessary structure, and that a, careful attention to culture is necessary, so as to produce the fibre best fitted for dyeing purposes. The second class of dyeing substances, where true 176 STRUCTURE OF THE COTTON FIBRE. chemical precipitates are formed within the fibre walls, are best illustrated by the pure mineral dyes such as chrome yellow, Prussian blue, and other dyes, where the reaction within the fibre which produces the colour is exactly the same as that which occurs in the test glass on the laboratory table when testing for lead or iron, and the art of dyeing these seems to me to be in the preparation of the fibre, so that it will receive in the best possible manner and to the fullest extent the solution of the substance which is after- wards to be precipitated. It seems that in the case of these dyes the action of the cellulose is purely passive, so far as its chemical action is concerned, and I think that this is in some measure confirmed by the fact that in some cases the dyeing material seems to assume a crystalline character within the tube walls, which shows that the molecules of colouring matter, or at any rate a large number of them, are not united by any chemical bond to the cellulose, but are free to exercise their crystalline affinities just in the same way as if they were within a neutral vessel. I have noticed this specially in the case of amber dye, when the chromate of lead was easily distinguished by the peculiar form of the crystals, the primary form being an oblique rhombic prism, which generally occurs with truncation of the basal and lateral edges. These form a pretty object when viewed with polarized light, which is very efficacious when employed to detect the occurrence of crystalline structure. These crystals in some cases seem to shoot through CRYSTALS IN FIBRE. 177 the walls of the cell membrane possibly in lines of fracture of the tube walls, and they not unfrequently seem to cause a weakness in the fibre by the sharp angles of the crystals cutting through the thin cellular walls when the fibre is subjected to strain. This probably occurs in other colours where the resulting dyes are readily crystallizable salts, and in some cases this may possibly account for some of the weakening action of certain dyes, just as in other cases when the dyeing material feeds the fibre and expands the tube walls the act of dyeing seems to confer additional strength. I have examined samples of amber dye however where this crystalline structure is entirely wanting, and I therefore think that the tendency to produce crystals may depend on the peculiar process which is employed in producing the colour, which may vary slightly at different times, or with the amount of colouring matter which has been introduced into the fibre. It may not be uninteresting to note that amber dye seems also very largely to coat the surface of thfc fibre as well as to pass into the tube walls. It accumulates in the twists and creases of the cotton filaments in a fine crystalline powder, and when viewed with reflected light gives a yellow glistening velvety appearance. The tendency to surface coating is manifest more or less in all colours, the dyeing materials having their attachment to the spaces between the individual hairs which form the thread, and in the spiral lines caused by the twist which has been put into the yarn in the process of spinning and N 178 STRUCTUKE OF THE COTTON FIBRE. doubling. I found that in many cases with these purely mineral dyes I could often remove the cellulose by a proper solvent, and leave the dyes which were associated with the fibre in an unchanged condition, showing that they had not in their aggregated form at any rate, entered into chemical union with the fibre, but were only mechanically associated. This surface colouring undoubtedly serves the purpose of masking many of the defects which would otherwise be visible arising from the imperfect dyeing of the individual fibres, but its ready removal in any after finishing process to which the yarn or goods may have to be subjected renders it a source of danger, as when removed it will reveal irregularities in colour which were not visible in the original yarn or goods before being subjected to these processes. Those who are acquainted with the union trade of this town (Bradford), know how frequently defects arise in cross dyed goods, caused by the stripping of the warps in the clearing process necessary for the dyeing of the weft, and unless the warp <^e is thoroughly fixed upon it streaky places are sure to appear, especially in cases where a large portion of the warp as well as the weft appears on the surface. Notwithstanding what has been said, however, I am not quite sure whether there is not an affinity between the impure cellulose, as it always exists in cotton fibre and the first solutions in which the fibre is immersed in order to produce these purely mineral dyes, so that they may act to some extent as mor- ACTION OF MORDANTS UPON FIBRE. 179 dants. I made a series of experiments to determine this point, and found that when cotton fibre was steeped in acetate of lead, which is the first process in the dyeing of amber, OT nitrate of iron, which is the first stage in dyeing Prussian blue, that I could never by any process which did not entirely destroy the very nature of the fibre remove all traces of these bases, which seemed to indicate that more than a mere mechanical union had taken place between them and the cellulose walls of the fibre, and although the cellulose itself may play no part in the reaction which occurs when the acetate is changed into the chromate of lead, or the nitrate of iron into the ferocyanide of iron, still it is in some way the reaction of the bases upon the cellulose which tend to give a greater degree of fixity to the colouring matter, which may, never- theless, be also present in much larger quantities than this union alone would warrant, and thus these dyes may be to a certain extent chemico-mechanical. In this way they may be said to shade into the third class of dyeing processes. The third class of dyeing substances where a mor- dant is used, vary in their nature and application very much indeed so much so, that in some cases as we shall afterwards see, there seems to be almost the formation of a new surface within the meshes of the fibre walls, or even in some cases on the surface of the thread, but permanently attached to it, upon which the colouring matter is deposited. We have already seen that if unprepared cotton 180 STRUCTURE OF THE COTTON FIBRE. fibres are placed in an aqueous solution of one of the aniline dyes they will not become permanently tinctured with the colour, and that, unlike wool or silk, any colour which they may have acquired is readily removed by washing. If, however, the yarn is first worked in a solution of tannic acid, which has a remarkable affinity for cotton fibre, the case is quite different, and the yarn will then take up the colour in large quantity and hold it permanently attached to the fibre. This is, indeed, one of the methods employed in dyeing aniline green where nitro-muriate of tin is also used to increase the effect. Salts of alumina are also used as the mordant for aniline, as in the case of the beautiful aniline blue where alum is the salt employed. Plate IX. gives an illustration of the appearance of the fibres when dyed aniline blue. I have been particularly struck when examining fibres dyed with any of the aniline colours at the much greater uni- formity in the levelness of the dyeing when compared with, say, indigo. Sections of the fibres seem to be uniformly coloured all through the cell walls, and there is a comparative absence of surface colouring and the tendency to form detached masses; some of the fibres, indeed, seem to be perfectly dyed in every part, as though the mordant had penetrated every portion of the cell walls. Any attempt by the use of solvents upon the cellulose to detach the colouring matter from the fibre seemed quite impossible, and I always found that the colouring matter and the Plate II 450 DIAMETERS. Cotton Fibres, dyed Aniline Blue ANILINE BLUE. 181 fibre matter were dissolved together, as though the union were perfect and complete. Of course, as will be seen from the plate, some fibres resisted the colour, and this was especially the case where the fibres were ribbon-like and possessed no distinct cell walls ; and it is quite possible that the union with the mordant, and through it with the cellulose, only takes place in the more spongy form, which constitutes the secondary deposits, and not with the outer and more dense epidermal layer. Mr. Crum notices this in his experiments with fibres mordanted with basic muriate of alumina, and remarks as follows : " It would appear that the primary cellular membrane, as found in the unripe plant, never acquires the power of absorbing colouring matter ; that its only purpose in dyeing is to enclose the soft and granular secondary matter which becomes deposited within it while it progresses towards maturity, and that that secondary matter has alone the faculty of attracting those mineral and vegetable substances which are either dyes themselves or which form dyes by attracting and combining with other bodies. The colourless character of the external membrane, however, is not to be discerned in the well-dyed fibre, just as we cannot by mere inspection detect the colourless character of the cell which contains a coloured juice in a natural flower, or like a thin tube of glass, which in appearance partakes also of the colour of any fluid that it may contain." I made a series of experiments with the view to determine whether any process of 182 STRUCTURE OF THE COTTON FIBRE. treatment would enable these unripe fibres to take the dye, and I found, like Mr. Crum, that by Mercerising them with strong alkali, which had the effect of thickening the tube walls, that their absorbent power was much increased ; but I also found that in the case of the aniline dyes, these unripe fibres could be dyed without any apparent thickening of the cell walls when the fibres were first bleached, or else sub- jected for some time to the action of weak boiling alkali. This may arise from the removal of any waxy matter from the outer layer, or else from the opening of its pores by the action of these reagents, although this same treatment seems to diminish its power to act as a dialyser when treated with salts of alumina. Alumina has a special interest in connection with the cotton fibre, because it not only possesses the peculiar property when in its hydrated condition of throwing down and heightening the brilliancy of many vegetable and animal colouring matters, but also of being separated from its various compounds by the dialytic action of the fibre alone, and thus retaining these colouring matters within the cell walls in an insoluble condition. Upon this action really depends the process of dyeing Turkey red, one of the most stable of all colours, and for which cotton is peculiarly suited. If an aqueous solution of alum, which is a com- pound of alumina, potash, sulphuric acid, and water, be taken and an alkali added, then falls to the bottom of the containing vessel a copious white, gelatinous HYDRATE OF ALUMINA. 183 looking precipitate, which is hydrate of alumina. If the alum solution contains colouring matter, such as cochineal or alizarine red, the precipitate of hydrate of alumina carries this colouring matter down with it and leaves the solution almost colourless. It does not seem that there is a chemical combination between the alumina and the colouring matter, but only as if the colloidal precipitate of the gelatinous hydrate entangled the finely divided colouring matter in its mass, in the same way that coagulating albumen in blood, or the white of eggs will clear the brown colouring matter out of concentrated solutions of sugar in the process of manufacture. When cotton fibres are steeped in an aqueous solu- tion of alum, and then after drying replaced in pure water, a precipitate of the hydrate of alumina is left within the cell walls and tube without the presence of an alkali. This most probably arises from the fact that the crystalloid portion of the alum diffuses through the outer pellicle into the surrounding water, while the colloidal has no such power, and remains behind. Other metallic oxides participate with alumina in this property to a varying extent, and all the coloured precipitates obtained by this line of treatment are usually known under the generic term of "lakes." Two of them, those produced by mordant- ing with mono-chloride of alumina, dyed with madder, and with oxychloride of iron, dyed with garancine, were exhaustively treated by Mr. Crum in the paper already mentioned, "On the Manner in which Cotton 184 STRUCTURE OF THE COTTON FIBRE. unites with. Colouring Matter;" * and in speaking of the former, he says : " Many of these fibres seem as if a thin film of alumina had originally been deposited within them over their whole length and breadth, and in all of them there is evidence of the deposit having shrunk to a great extent in both directions in the process of dyeing. It is remarkable that the alumina should adhere so slightly to the membrane which contains it, as thus to shift without difficulty from one part of it to another in the act of shrinking. The same remark applies to the clots found in the centre of full grown cotton, whether the mordant of iron or alumina be applied from an acetic solution, or, as in the case before us, from a basic solution." These appearances will be distinctly seen by looking at Plate X., where the colouring matter as associated with different fibres is delineated. In the kempy fibre many parts are quite uncoloured by the dye, while in the unripe pellucid fibre the colouring matter is confined to a thin layer, which by the act of shrinking has become separated into distinct flakes detached from each other and distributed irregularly through the thin tube. The fully dyed fibre shows the accumulation of colouring matter within the interior of the tube. In Plate XL the transverse sections of the fibres show the different distribution of the colouring matter in the lateral direction, some of the fibres being hardly coloured at all, while others have the * Chemical Journal. New Series. Vol. i., p. 410. Plate B nc 450 DIAMETERS. Cotton Fibres dyed with Lake of Alumina and Madder. i A. Kempy .fibre. B. Unripe pelucid fibre. C. Fully ripe dyed fibre. D and E. Partially dyed fibres. ALUMINOUS LAKES. 185 dye collected in the form of a mass or clot within the interior of the tube. The distribution of the dye in the cell walls is also distinctly seen, and in some instances reveals the distinct appearance of lamination in the walls. One of the fully ripe fibres exhibits the appearance of an uncoloured outer pellicle, while the interior is well dyed through to the centre. " By previous bleaching of this fibre the quantity of alumina which it can receive is much diminished, but enough is admitted to form with it a most in- teresting microscopic object. In all cases the cell remains beautifully colourless and crystalline, enclosing its flakes of carmine ; and the variety in the distribution of these flakes is infinite. The effect of bleaching in diminishing the power of cotton to receive mordants is to be attri- buted to the boiling in weak solutions of quicklime and carbonate of soda to which the cotton is sub- jected, and not to hypochlorite of lime, which is very sparingly used in* the process of bleaching, nor to the sulphuric acid, which does not affect the mordanting. Hot alkaline solutions, though weak, mat together the young fibres and close their passages against the admission of mordants. They have a similar tendency when applied to riper cottons, while that of strong caustic alkaline solutions is, as we have seen, to open them. Hypochlorites in excess also open the pores of ripe cotton, and by enabling them to admit more mordants greatly increase the intensity of the dye." 186 STRUCTURE OF THE COTTON FIBRE. The process of dyeing Turkey red, which is one of the most beautiful and stable of colours, is essentially a madder or alizarine red, dyed upon an aluminous basis, the fibre being previously prepared with oil ; but its successful production demands the most care- ful attention to detail and mechanical manipulation, which is only attained by a comparatively few firms, and the whole of the principles involved in the chemical changes are by no means yet thoroughly understood, although it has received the attention of many eminent chemists. It almost seems, indeed, to be the production of an artificial dyeing surface within the cellulose walls, which is itself united to the fibre, or enclosed within it, but so topically that, notwithstanding the severe process to which the thread is subjected during the dyeing process, the centre of the thread is seldom dyed, except very partially, while the surface possesses the most rich and deep colour. We know that the richness and lustre of silk, both in its dyed and undyed state, arise from the gelatinous and albuminous surface, which forms the outer coating of the fibre, and which is the basis upon which the colour is fixed; and it is quite possible that further discoveries in organic chemistry may enable us to carry out in other colours and in other methods of dyeing the production of artificial surfaces within the meshes of the cotton fibre, which will increase its power of receiving colour and impart greater brilliancy and depth to the shades. At any rate, it is worth the while of students in this Plate XI 450 DIAMETERS Sections of Cotton Fibres dyed wi th Lake of Alumina and Madder, Exhibiting various degrees of Colour acquired by the fibre. ENDOCHROME IN FIBRE. 187 school to turn their attention to the matter as a field for investigation, which may reward their labours. We most of us know that in this neighbourhood a gentleman discovered the means of imparting a metallic lustre to fibres, but that the want of flexibility in the yarn after the process was complete rendered the artificial surface liable to crack, and thus became easily removeable by mechanical friction ; but it appears to me that a flexible lustrous surface is not beyond one of the possibilities of modern science. "We have already noticed that along with Egyptian cotton, especially the indigenous variety, there is always associated more or less endochrome or colour- ing matter, which gives a dark reddish brown or golden colour to the fibre. This colour is not evenly distributed through the fibre, but occurs most fre- quently towards the upper end of the fibre, where it has been most exposed to the action of light, and also is unevenly distributed in the boll. It appears when examined under the microscope not only in the interior of the tube, but also associated with the layers which form the thickness of the tube walls. In some of the best classes of Egyptian cotton I have seen this sufficiently distinct and uniform to be used in fancy goods without dyeing; and it is often necessary to bleach this colouring matter out of the fibre before it can be made sufficiently colourless to receive the lighter shades of fancy colours. When Egyptian and American cotton yarns are placed side by side this difference in colour is very striking, and 188 STRUCTURE OF THE COTTON FIBRE. forms a ready method of distinguishing between the two. To go further into the relations of the cotton fibre to dyeing materials would open up the whole subject of cotton dyeing generally, which is beyond the scope of our lectures; but enough has been said to point out the general principles upon which the whole of the dyeing processes depend, and to show that the variations in the mechanical structure and arrangement of the ultimate parts of which the fibre is composed have a great effect upon the readiness with which it can be made to receive an even and permanent colour. It cannot be too strongly impressed upon the minds of those who are engaged in these operations that the cellulose walls of the fibre are to a great extent passive, so far as any chemical action is concerned, in the great majority of instances, and that the best results will always be attained by subjecting the fibre to such processes as will remove any foreign matter which prevents the free action of the cellulose mem- brane as a dialyser. While the structure of the fibre itself sometimes interferes with the dyeing of the cotton, there are undoubtedly many other imperfections in goods which are not the result of this, but arise from other causes, some of which it may not be uninteresting to mention. I remember on one occasion being called to look at some pieces which had taken the dye very unevenly in the warp. The pieces were woven in the grey and cross-dyed afterwards. For many inches in IMPERFECTIONS IN DYEING. 189 some places in particular threads, and sometimes in more than one thread the colour seemed hardly to have taken in the warp. The dyer and finisher thought it was something mixed in the cotton as it was quite impossible to get it even. When I exam- ined the thread under the microscope, I found small particles or masses of a waxy substance sticking in the hairs, and when I pointed this out and enquiry was made, it was discovered that in consequence of the slack nature of the twist in the warp and its consequent want of strength, a wax roller had been used, over which the warp passed to give it strength. The same warps woven without the roller took the dye perfectly. Another great source of imperfection arises from the cotton-seed oil which is present in the small broken pieces of seed, which in imperfectly carded yarn, and indeed in a more or less degree in all uncombed yarns, are attached to the fibre and often spun into its texture. The oil which exudes from these portions of seed penetrates into the adjacent fibres and often possesses such a diffusive power, especially when subjected to heat, such as the hot rollers in finishing, that it will extend a considerable distance all round, and in some cases, will extend even to the thread on each side of the one where the fragment of seed is lodged. In Egyptian cotton the short hairs which are attached to the seed and cannot be removed from it by the ginning process are peculiarly liable to be thus saturated, and when they 190 STRUCTUKE OF THE COTTON FIBRE. accumulate in small masses on the surface of the thread they are apt to cause imperfections because the dye is only deposited on the surface, as the seed oil within prevents the dye penetrating, and in the finishing process, especially when the face of the piece is singed, the surface of these small fuzzy lumps is disturbed, and the undyed fibre beneath presents a marked contrast to the more thoroughly dyed thread on each side. Whenever light shades are to be dyed, it is important with carded Egyptian yarns that great care should be used in the clearing of the yarn, so as to completely remove all the traces of this oil from the fibre, otherwise it is almost sure to cause more or less imperfection. I remember seeing a piece of cloth which was spotted all over the light surface with more or less dark dots, and upon examining each of these with the microscope I found a small bit of seed in the centre of each, out of which a drop of oil had been squeezed by the pressure of the hot finishing rollers, which had no doubt also by the heat made the oil more liquid, and thus caused it to run into the fibre. On this account the importance of the ginning process cannot be over-estimated, because unless the separa- tion of the fibre from the seed is as complete as possible the remaining seeds which are carried along with the fibre are apt to be broken up in the earlier cleaning processes into small bits, which cannot be removed by the process of carding, and then pass forward into the yarn each with their supply of associated oil. In single warps which require sizing IMPERFECTIONS IN DYEING. 191 to make them weave, the composition of the size is an important matter when the weft has to be dyed after the piece is woven, for although in this district heavy sizing in the finishing of the goods does not pertain so much as in the heavy cotton trade of Lan- cashire, still it does exist to some extent. In Lancashire I have seen coloured stains produced by the action of foreign substances upon the substance of the size and then fixed into the fibre itself, as well as the production of mildew which arises from micro- scopic fungus growths which feed upon the substance of the size. The utmost importance also attaches to the perfect cleansing of the various vessels and machines used in dyeing and finishing before being used for different classes of goods, and undoubtedly many mysterious imperfections may be traced to the neglect of these precautions and to a variation in the quality of the water used in dyeing. Even the volatile substances which may be conveyed in the steam used for dyeing purposes, and which may arise from the use of various boiler anti-incrustation compositions have been known to affect the dyeing and bleaching. I remember seeing some pieces where the surface was strangely marked with uneven shades in the finished goods, which imperfections were not at all visible till the last process was complete. This process consisted in sub- jecting the goods to hydraulic pressure between hot iron plates with mill boards between the folds of the cloth. These mill boards had been used with a cloth 192 STRUCTURE OF THE COTTON FIBRE. which was either imperfectly cleared after dyeing, or some portion of the dye was taken into the surface of the mill board and transferred to the face of the new cloth so as to discharge under the action of the heat a portion of the dye, and thus produce the mottled appearance. When new boards were substituted the same goods came up quite perfect, although nothing was present on the surface of the old boards in sufficient quantity to be detected by the eye, or even by the ordinary processes of chemical analysis. I have even known the presence of volatile substances such as creasote, carbolic acid, and chlorine in the atmosphere to affect the dyeing of the fibre of yarns which have been stored in the bundle or warp in the same room in which these materials were present a result which, however, we might almost anticipate from the great power which cotton possesses of absorbing gases. The variation in the colour of the cotton from year to year, or even of different mixings, when sufficient care in selection is not used, often affects the evenness of the dyeing process. This is usually however visible in the warp before dyeing, and can then be removed when light shades are required. I have also found that different classes of cotton vary in their power to receive a full and even dye, but that this distinction which is quite invisible to the eye can be detected readily even in the grey state by the proper use of polarized light, which reveals minute differences in molecular structure with extraordinary distinctness. I may also mention that CROSS-DYEING. 193 this light enables us to select the complimentary colour to any given shade, which being the full effect of the rays which are suppressed by the reflecting surface, is that shade or colour which will harmonize best with it and produce the greatest contrast, a knowledge which is of the highest service to all engaged in designing and executing fancy goods. As already mentioned, there is always more difficulty in preventing defects when the pieces are cross-dyed, because the process of dyeing the weft often has a marked effect upon the colour of the warp, and it is not possible always to allow for this in the original dyeing of the warp. I saw recently a large number of samples of the very fastest colours which could be dyed on cotton, and which had been passed along with some pieces through the cross-dyeing process, and I was very much struck with the great change produced when compared with the original samples. This subject needs indeed a thorough investigation as I am quite sure, that since all effects have a cause, many of the defects which are continually turning up are the result of preventible causes, and may either be greatly ameliorated or entirely obviated. It would be impossible to mention all the causes which I have known to interfere with the proper reception of dye by the fibre, but I think I have called your attention to a sufficient number of them to show the importance of attention to every detail in the process of manufacture, without which success is impossible, even when the greatest care has been Q 194 STRUCTURE OF THE COTTON FIBRE. exercised in the proper selection of the raw material. The cotton in some seasons undoubtedly requires a different treatment from that which yields the best results at other times, just as the practical spinner finds he has to vary the district from which he draws his supplies in different years if he is to obtain a constant standard of yarn. Undoubtedly one of the directions to which we must look for increased efficiency in the colouring of our yarn and goods is the discovery of further preparatory processes which, like the Mercerising by strong alkaline fluids, will impart an increased receptive efficiency to those fibres which are always present more or less in all cotton in an immature condition, and also impart to the ripe fibre a greater toughness and strength. I know of no field which offers a wider scope for research to the members of a technical school than the investigation of such a subject as this. The artificial production of alizarine has already produced a complete revolution in the processes of calico printing and Turkey red dyeing, and threatens indeed to remove the latter from the category of a special "technic" to that of an ordinary dyeing process; and the recent synthesis of indigo points to a similar revolution in indigo dyeing, which is to a certain extent already in operation.*" As this is quite a recent discovery, it may not be uninteresting to mention, for the benefit of those who are chemists, * Journal of the Chemical Society. No. ccxxii., page 179. ARTIFICIAL PRODUCTION OF INDIGO. 195 that the point of departure in the artificial manufac- ture of indigo is cinnamic acid, which was first pro- duced from oil of bitter almonds, but is now derived from toluene, a coal-tar product, and the last link in the chain is orthonitrophenylpropiolic acid, from an alkaline solution of which pure indigo blue separates out on heating with grape sugar. The yield of indigo is about 48 per cent, of the propiolic acid, the theoretical amount being 68 per cent. M. Baeyer, the discoverer, believes that the indigo molecule contains at least twice C 16 H 10 N 2 2 . As the science of chemistry advances we may expect a continuous simplification of our present methods of imparting colour to fibres, but all these methods will still depend on a careful adaptation of them to the structural nature of the raw material itself. I feel fully persuaded that we have not yet penetrated beyond the threshold of our knowledge respecting the means which may be ultimately em- ployed in associating along with our dyeing processes, also the conferring of increased strength and smooth- ness on the fibre. The wonderful change which occurs in the manufacture of parchment paper, in which, by the action of concentrated sulphuric acid, a strip which originally would not support more than three or four pounds weight when dry, and scarcely an ounce when wet, can be made to carry over thirty pounds either wet or dry, seems to me to indicate that there must lie within the reach of possible discovery a chemical process of strengthening yarn at the same 196 STRUCTURE OF THE COTTON FIBRE. time as dyeing it, since cellulose is the basis of both parchment paper and cotton yarn. A careful examination of almost any dyed yarn reveals how superficial after all are our best dyeing processes, the untwisted fibres exhibiting in many places under the microscope a complete want of colour. Even in Turkey red, where the process is most severe, the dyeing material is to a very large extent on the surface only, and a slight curl in the yarn prevents the thread from receiving the dye in many parts even on the surface. This is a very important matter, since it shows how very slight is the penetrative power of chemical fluids even when under such favourable conditions as high temperature and pressure. It shows the difficulty of thoroughly dyeing the fibres after they have been spun into yarn, and yet, if dyed in the condition of cotton wool before the process of manufacture is commenced, there are also a series of difficulties intro- duced, not altogether mechanical, which it appears to me must necessarily limit the application of such a process. In the case of some colours this has been attended with marked success, and may possibly have a future before it specially for coloured wefts. How- ever this may be, we may rest assured that the more we give our attention to the real nature of the raw material with which we have to deal, -the better shall we be enabled to turn all its specialities to the best account, and be enabled to remove from the list of uncertainties many of the processes which we at EFFECTS OF TECHNICAL EDUCATION. 197 present employ, so as to produce a higher class of work and attain a greater final perfection. There is a great danger of resting satisfied with the present condition of things, especially when trade is pursued with the sole object of making money, and without the introduction of a spirit of pride in the attainment of better and higher results; and one of the benefits of a true technical education will un- doubtedly be the implanting in the minds of the rising generation of an intelligent interest in the philosophical and scientific questions which underlie all our industrial applications of natural laws. We must remember that we can only successfully work through these laws, and not in opposition to them, and that we can never reach the highest pos- sible in perfection of our results without the careful application of these laws throughout the whole of the successive stages of the manufacture. The perfection of the whole depends upon the perfection of the parts ; and one great object which I have in view in these lectures is to stimulate those who are young and energetic, and who have life before them, to give their attention to the first principles of the processes in which they are likely to be engaged, so as to find out the very best means of giving a perfection to the most minute parts of their raw material. Longfellow assures us " In the elder days of art Sculptors wrought with nicest care Every close and unseen part, For the gods see everywhere." 198 STRUCTURE OF THE COTTON FIBRE. That careful attention to detail which always marks the true workman must be carried by us into the recesses of all our manufacturing processes. Know- ledge and science may enable us to do this, without a material increase in the cost, if we call to our aid the instruments which the latter has placed in our hands to enable us to look at the ultimate structure of the materials upon which we have to work, and use the best machinery to transform it, and in the future, as in the past, material prosperity will crown the labours of those whose successful application of theoretical knowledge strengthens the hands of industry, and opens the stores of the world's riches to the teeming millions who are waiting to possess them. GLOSSARY; OB, Explanations of some of the terms used in this work. Achromatic condenser. A compound lense used for concen- trating the light on to the object under the microscope. Affinity. Chemical attraction or cohesion. Albuminous matter. Matter possessing the same properties as the white of an egg. Alizarine. The red colouring matter of the madder root; now obtained from coal tar. Amorphous. Possessing no regular structure ; like jelly or treacle. Analysis. The breaking-up of a substance into its simplest constituents, so as to determine their qualitative or quantita- tive relations. Aniline. One of the colouring matters derived from coal tar. Atom. The smallest part into which any elementary substance can be divided. Atomic. Relating to atoms. Atomicity. The power which an atom possesses of holding one or more other atoms in combination. Automatic. A machine which acts without the necessity for human supervision. 200 STRUCTURE OF THE COTTON FIBRE. Axis. In the microscope the axis is represented by a line drawn through both the eye-piece and object glass. Battery. When applied to microscopy, signifies a full range of eye-pieces and object glasses, giving a variety of magnifying power. Binocular. A microscope with two tubes and eye-pieces, so that both eyes can be used for observation at once. Boll. The seed vessel of the cotton plant when expanded by the cotton fibre, Catalictic. The chemical action which one substance produces upon another without undergoing change itself. Calyx. The outer covering or cup of a flower. Capsule. The vessel which contains the seed of the plant. Carpel. The leaf forming the pistil of a flower. Cambium layer. Mucilaginous cells between the bark and young wood in plants. Carding. One of the early processes in spinning cotton, drawing the fibres through fine wire teeth fixed on rollers revolving at different speeds. Card-room. The room in a mill where the process of prepara- tion by carding is carried on. Cellulose. The chemical substance of which the cell wall in plants is composed. Cerosine. Wax prepared from the leaves of the sugar cane. Coarse adjustment. That part of the microscope by which the first focussing of the object-glass on to the object is accom- plished. Clamping arc. A portion of a circle on the microscope with screw to fix it in any position. Collodion. A solution of gun cotton in ether and alcohol. Colloid. A substance which will not crystallize. Combing machine. A machine for selecting the fibres of cotton of uniform length and cleansing them from mechanical impurities. GLOSS AEY. 201 Complimentary colour. The remaining colours in a beam of light which are necessary to make white light. Cop. The yam accumulated on the spindle of a mule or twiner in a conico-cylindrical form, and removed when the spindle is full. Counts. When applied to yarn, means the relative fineness of the thread. Corypha cerifera. The Carnauba palm. Cross dyeing. The process of dyeing the warp before weaving, and the weft afterwards. Crystalloid. A metallic or organic substance which possesses the power of crystallizing. Denticulated. Having teeth like a saw. Dessicate. To dry up. Diameters. When applied to microscopy, signifies the number of times that a linear inch is magnified by the eye-piece and object-glass in use. Dialyser. A membrane which possesses the power of allowing certain substances in solution to pass through it, while it rejects others in the same solution. Dicotyledon. A plant whose seed is divided into two lobes. Dhollerah Cotton. A class of East India cotton. Drawing. In cotton spinning, a process which arranges the fibres in parallel lines by passing them through rollers running at different speeds. Endochrome. The colouring matter within vegetable cells. Epidermal layer. The outer layer or skin of a fibre, or layer organism. Eye-piece. The top part of the microscope to which the eye is applied, and which can be removed at pleasure to increase or diminish the magnifying power. Exogen. A plant which grows by additions made on the outside of the trunk. Fibrillse. The strands or minute chain of cells forming secondary deposits. 202 STRUCTURE OF THE COTTON FIBRE. Fine adjustment. The arrangement by which the final focussing of the object-glass is accomplished in the microscope. Finishing. The last process to which textile fabrics are sub- jected, so as to straighten out and improve the surface. Germinal cells. Cells in the process of growth, or from which other cells are springing. Ginning. The mechanical process by which the cotton fibre when ripe is separated from the seed. Goniometer. An instrument for measuring small angles. Gun Cotton. Cotton which by steeping in a strong solution of nitro-sulphuric acid has become explosive. Homogeneous. Possessing one uniform molecular structure throughout. Hot finishing. The process of forming an artificial gloss upon the surface of goods by the use of hot rollers. Hydroxyl. The substance produced by the union of a single atom of hydrogen and oxygen. Hygrometric. Relating to the degree of moisture in the air. Incinerate. To burn to ashes. Indigenous. Native to the country. Inspissated. Dried up. Inverted pendulum. An instrument for measuring small vibrations. Kemp. A solid structureless fibre without internal tube. Laminated. Built up in layers. Laps. Rolls of cotton from which the carding engines are fed. Leicestershire hog. The first clipping of wool from a Leicester- shire sheep. Linear development. Growth in a straight line, not all round. Madder. A plant from whose root the red colouring matter called alizarine was formerly extracted. GLOSSARY. 203 Malvaceae. A natural order of plants, of which the mallow is a type. Mercerising. Subjecting cotton fibres to the action of strong caustic soda. Meteorological. Relating to weather and climate. Micrometer. An instrument for measuring the diameter of very small objects. Microscope. An instrument for magnifying small objects. Milled-head. A screw with the edge or circumference of the head cut into grooves like the edge of a sovereign. Millboard. Thick cardboard placed between the folds of cloth during the process of pressing. Mohair. The hair from a particular species of goat. Molecule. The smallest portion of any compound substance in which the peculiar chemical properties of the body can inhere. Monocotyledon. A plant whose seed has only one lobe. Monocular. A microscope, with which only one eye can be used at once. Monochromatic. Possessing only one colour. Mordant. A reagent which forms the bond of union between the fibre and colouring matter. Mule. A machine for spinning yarn, in which the spindles are placed upon a carriage which draws out from the rollers when the yarn is spinning and returns to them when the yarn is being wound on to the cop. Murexide. A rich purple colour obtained by the action of nitric acid upon uric acid. Neps. Short immature fibres or portions of tangled broken mature fibre. Object-glass. The small compound lens which first receives the rays of light from the object under examination. Objective. A short name for the object-glass. Oleaginous. Of the nature of oil. Ovary. That part of a plant in which the seeds are contained. 204 STKUCTUKE OE THE COTTON FIBEE. Parachute. The hairy portion of a seed which enables it to be distributed by the action of the wind. Parapectic acid. A product derived from pectic acid. Pectic acid. The gelatinous acid formed by the decomposition of pectin, which is found in nearly all vegetable substances. Pellicle. A thin transparent membrane. Pitch of screw. The distance at which the threads of a screw are apart from each other. Placenta. The cellular part of the carpel, to which the seed is attached. Plumbic iodide. A combination of lead and iodine. Plexus. A tangled mass of fibre. Polarized light. A ray or rays of light, in which all the lumi- nous vibrations are either in one plane or in two planes at right angles to each other. Circular or elliptically polarized light is when the plane or planes of polarization are rotating round the axis of the ray in a circular or elliptical form. Polarizing prism. An oblique rhomb of crystal used for polarizing light. Polysepalous. A seed-vessel having many divisions. Preparing machinery. Scutching and card-room machinery up to the roving frames. Protoplasm. The primative matter which forms the structure of cells and is the physical basis of life. Reagent. A chemical substance used to act upon another sub- stance as a test of its nature. Roving. The soft thick thread out of which yarn is spun in a frame or mule. Rules of thumb. Practical, not theoretical, receipts for any process. Schweitzer's solvent. An ammoniacal solution of oxide of copper, Secondary deposits. The substance deposited upon the primary, cell wall. GLOSSARY. 205 Septem. A thin, porous layer between two liquids or gases through which they transfuse. Sericin. The chemical substance of which silk is formed. Setting of yarn. Storing yarn in a damp place till the curl is taken out of it, or subjecting it to steam pressure for the same purpose. Size. A paste of flour, starch, or other stiffening substances which are used to give strength to yam previous to weaving, or to give a body to the cloth. Snarls. Small curled places in yarn. Spiral structure. Secondary deposits on the outer cell wall in a spiral form. Stage. That portion of the microscope upon which the object is placed for examination. Stereoscope. An optical instrument for two eyes so as to obtain the effect of seeing an object from two angles as in ordinary vision. Swift. That part of a wrap reel or reeling machine upon which the yam is wound so as to form the hank. Tannin. An astringent substance found in oak and other barks. Technical. Relation of art to manufactures. Technologist. One who applies science or art to manufactures. Tester. A machine for testing the strength of yarn. Textile. Woven fabrics. Throstle. A spinning frame, with flyer, or ring and traveller, which spins on to a bobbin. Trinitrocellulose. Gun cotton. Twist Tester. A machine for testing the number of twists or turns in a thread of spun yarn. Ultimate fibres. The smallest part of an organic structure which can be separated without destroying the organic struc- ture altogether. Union Trade. The trade in mixed fabrics, made usually with a cotton warp and worsted or woollen weft. 206 STRUCTURE OF THE COTTON FIBRE. Water of Hydration. The water which forms an integral por- tion of the structure of a body. Warp. The yarn which runs in the direction of the length of a piece of goods. Weft. The yarn which runs across the warp from side to side. Worm wheel. A toothed wheel driven by the revolution of a screw or worm, into the threads of which it works. Wrap reel. A machine for winding yarn off cops, or bobbins, or hanks, and measuring the length of the yarn. Yarn. Fibre when spun into thread. Yarn tester. A machine for testing the strength of yarn. Zero. The point on any scale of measurement from which numeration commences. INDEX. Absorption of gases, 73 ,, liquids into fibre, 164 Acid Action of mineral, 72 organic, 71 sulphuric, 66 mtro-sulphuric, 72 citric, 71 silicic, 71 Action of fibres on aniline colours, 167 Action of bleaching on fibre, 185 mordants on fibre, 179 secondary deposits, 181 ,, weak alkalies, 182 ,, hypochlorites, 185 Adjustment of micrometer, 13 ,, yarn tester, 119 African cotton, 48, 100 Alizarine, artificial, 194 Alumina, 182 Aluminous lakes, 183 American cotton, 94 Ammonia, absorption of, 73 Ammonio-cupric solvent, 50 Amber dye, 176 Analysis of cellulose, 60 cotton wax, 57 ,, ash, 68 ,, samples, 69 colouring matter, 77 dyeing processes, 168 Aniline green, 180 blue, 180 Artificial indigo, 194 ,, parchment, 66, 195 B Balance, 120 Bengal cotton, 100 Bleaching, action on fibre, 185 Boll cotton, 17 Bolley's experiments, 74, 161 Brazilian cotton, 93 Bud cotton, 17 Calculation of counts, 110 Carnauba wax, 58 Cause of irregularity in yarn, 152 lustre on fibre, 156, 186 ,, colour, 158 ,, defects in dyeing, 35, 75, 85, 87, 188 Caustic soda, action of, 52 Cell contents, 27 ,, walls, structure of, 49 Cellulose, 60 ,, molecule, 61 Cerosine, 58 Chevreul's theory of dyeing, 163 Chinese wool, 30 Chemical combination, 65 Chrome yellow, 176 Citric acid, action of, 71 Cinammic acid, 195 Classification of fibres, 34, 45 ,, cottons, 89, 99 ,, dyeing processes, 168 Colloids, 166 Collodion, 76 Colouring matter in fibre, 77, 187 ,, ,, analysis of, 77 208 INDEX. Cotton, American, 94, 100 Cotton planting, 18 99 ash, 68 pod, 23 Aracata, 99 Rangoon, 100 99 Australian, 99 Rio Grande, 99 99 Bahia, 99 Sea Island, 89, 99 Bengal, 100 seed, 24 99 Broach, 100 sections of pod, 24 99 brown Egyptian, 99 fibres, 41, 185 99 Brazilian, 93, 99 species of, 15 blooming time, 18 Scinde, 100 99 boll, 17 Sedge, 52 99 bud, 17 Smyrna, 99 99 Ceara, 99 Surat, 96, 100 99 cell, 25 Tahiti, 99 9 9 classes of, 89, 99 Tinnivelly, 100 99 cultivation, 17 Texas, 100 99 Comptah, 100 Upland, 100 9 9 diameter of fibres, 20, 99 Veravul, 100 Dharwar, 100 wax, 57 99 Dhollerah, 100 Western Madras, 100 9 9 Egyptian, 90, 99 white Egyptian, 99 9 9 Egyptian, brown, 99 Counts of yarn, 110 99 Gallini, 99 Cross dyeing, 4, 178 ,, white, 99 Crum's experiments, 53, 165, 183 fibre, 39, 45 ,, theory of dyeing, 164 99 ,, structure of, 40, 49 Crystals in fibre, 84 99 flower of, 17 Fiji, 99 D Florida, 99 Dancer's experiments, 51 If growth of, 25 Defects in dyeing, 35, 75, 80, 87, 99 gun, 65 Haytien, 99 188 Dessication of fibre, 29 99 99 Hingunghat, 100 Indian, 96, 100 ,, cotton, 63 Development of fibre, 25 influence of climate on, 18, Dharwar cotton, 100 85 Dhollerah 100 Kemps in, 35, 88 Dialysis, 166 99 La Guayran, 99 Dollfus's experiments, 71 19 length of fibres, 20, 99 lamination of fibres, 43 E 9 9 Maceo, 99 Early investigations, 29 Madras, 100 Effect of seasons, 85 magnified fibres, 11 ,, oil in fibre, 86, 189 Maranham, 99 Egyptian cotton, 90, 99 mature, 38 Electrical action, 56 " mineral constituents of, 67 Endochrome, 76, 187 Mobile, 100 Eriophorum polystachyum, 52 || nitrogen in, 70 Experiments on strength of yarn, oil, 55 121 9 9 oil in fibre, 189 Experiments on twist in yarn, 142 9 9 Oomrawuttee, 100 Orleans, 100 F " Pariaba, 99 Fatty acids, 59 Peruvian, 93, 99 Fibre, Chinese wool, 30 " ,, rough, 48, 99 ,, diameter of, 20 ,, smooth, 99 fracture of, 83 J? Pernam, 99 ,, kempsin, 35, 88 INDEX. 209 Fibre, Leicestershire wool, 31 ,, length of, 20, 99 ,, mohair, 31 ,, sections of, 41, 185 silk, 32 ,, strength of, 81 Fiji cotton, 99 Finishing (hot), 4 Flower ot cotton plant, 17 Florida cotton, 99 Gas, absorption of, 73 Gallini cotton, 99 General results of tests for strength of yarn, 139 General results of tests for counts of yarn, 140 General results of tests for twist in yarn, 152 Gossypium Arboreum, 15, 16 Barbadense, 15, 16 Herbaceum, 35, 16 Hirsutum, 15 Keligiosum, 15, 16 Sandwichense, 15 Tahitense, 15 Graham's experiments, 166 Gun cotton, 65 H Hank in cotton, 110 Haytien cotton, 99 Herbaceous cotton, 16, 17 Hingunghat cotton, 100 Hypochlorites, action of, 185 Hydrate of alumina, 183 Hydroxyl, 61 Hydration, water of, 63 Immature fibre, 26 Imperfections in dyeing, 188 Improvements in dyeing, 175, 194 ,, preparing, 109, 188, 194 Impurities in size, 191 Indian cotton, 96 Indigo blue, 172 Indigo, artificial, 194 Influence of fibre on colouring matter, 162 Interference lines, 43 Irregularities in twofold yarn, 140 ,, single yarn, 140 Iron in fibre, 68, 78 K Kemps in fibre, 35, 88 Kuhlmann's experiments, 162 La Guayran cotton, 99 Lea in cotton, 110 Lectures, division of, 6 Leicestershire wool, 31 Light polarized, 10, 192 Limit of spinning, 108 ,, vision, 157 Lustre on fibre, 158, 186 M Maceo cotton, 99 Madras cotton, 100 Malvaceae, 14 Maranham cotton, 99 Margaric acid, 59 Magnifying power, 11 Manufacturing, science of, 3 Measurement of fibres, 19 Mechanical manipulation, 104 Method of fracture of fibres, 83 Metallic lustre on fibre, 187 Mercer's experiments, 52 Mercerising process, 53 Microscope, 7 Micrometer, 11 ,, adjustment of, 13 Microscopic power, 11 Mineral constituents of cotton, 67 ,, acids, action of, 72 ,, colours, 163 Mobile cotton, 100 Moisture in cotton, 62 Mohair, 31 Monochloride of alumina, 183 Mordants, action of, 178 N Neps in cotton, 26, 91 New crop cotton, 55, 107 Nitrogen in cotton, 70 Nitro-sulphuric acid, action of, 64 O Oil in fibre, 86, 189 O'Neill's experiments, 50, 81 Organic acids, action of, 71 Oomrawuttee cotton, 100 Orleans cotton, 100 Orthonitrophenylpropiolic acid, 195 Oxalic acid, action of, 71 Oxy chloride of iron, 183 Oxygen, absorption of, 73 210 INDEX. Parchment paper, 66, 194 Parallel wire micrometer, 12 Paraiba cotton, 99 Parapectic acid, 59 Pectic acid, 59 Penetration of colouring matter, 161 Pernam cotton, 94, 99 Peruvian cotton, 16, 49, 93, 99 Polarized light, 10, 176, 192 Precautions in testing yarn, 120 Principles of spinning, 105 R Rangoon cotton, 100 Reflected light, use of, 33 Regularity of twist in yarn, 152 ,, strength in yarn, 139 ,, counts in yarn, 140 Relation of time to dyeing process, 170 Relation of animal fibres to colour- ing matter, 162 Relative strength of fibres, 81 ,, length of fibres 20, 99 Representation of fibres, 39 Reversion of fibres, 49 Rio Grande cotton, 99 Ripening of fibres, 27, 53 Rough Peruvian, 48, 99 Samples of yarn, 112, 147 Sand in cotton, 69 Saxony wool, 31 Scales on wool, 31 Science of manufacturing, 3 Scinde cotton, 100 Schweitzer's solvent, 50 Seasons, effect of different, 85 Seat of endochrome, 187 Sea Island cotton, 89, 99 Section of fibres, 41, 185 Secondary deposits, 46 ,, ,, in their rela- tion to dyeing, 181 Selection of samples, 121 Serrations on wool, 31 Setting of yarn, 56 Silk, structure of, 32 ,, length of fibre, 32 ,, surface of, 186 Silicic acid, action of, 71 Shrinking of colour, 184 Shrub cotton, 16 Smyrna cotton, 99 Species of cotton, 15 Spider's web micrometer, 11 Spinning of cotton, 105 ,, coloured cotton, 197 Spiral fibres, 47, 50, 51 ,, form of fibre, 154 Strength of fibres, 81 Stripping of warps, 178 Structure of cotton, 39, 40, 50, 51 ,, cotton pod, 23 silk, 32 ,, wool, 30 ,, cellulose, 61 ,, gun cotton, 65 ,, laminated, 43 Sugar cane wax, 58 Sulphuric acid, action of, 66 Surat cotton, 16, 96, 100 Synthesis of indigo, 197 Table of counts and weight, 111 length of fibres, 20, 99 , , diameters of fibres, 20 ,, strength of fibres, 81 ,, ,, yarns, 112 Tannic acid, action of, 180 Tannin in fibre, 87 Tahiti cotton, 15, 99 Tartaric acid, action of, 71 Technical education, 2, 197 Tester for strength, 116 ,, ,, twist, 144 Texas cotton, 100 Theoretical strength in yarn, 141 Theory of dyeing, 159, 163 Tinnivelly cotton, 100 Toluene, 195 Transmitted light, use of, 33 Transverse section of fibres, 41, 184 Tree cotton, 16 Trinitro cellulose, 65 Trough ton's micrometer, 12 U Unchanged juices in fibre, 87 Union trade, 5, 178 Upland cotton, 100 V Variation in diameter of fibres, 21 ,, fibres, 21 length of fibres, 20, 21, GO ,, ripeness, 79 ,, strength of yarn, 122, 139 ,, counts of yarn, 140 INDEX. 211 Variation in twist in yarn, 152 Varieties of cotton, 97, 99, 100 Vacuum for setting yarn, 56 Veravul cotton, 100 Vision, limit of, 157 Volatile substances, influence dyeing, 191 W Water in cotton, 62 ,, of hydration, 63 Wax rollers, use of, 189 Weight of fibres, 23 ,, counts, 100 Western Madras cotton, 100 West Indian cotton, 99 White Egyptian cotton, 99 White indigo, 173 Wild cotton, 49 Wool, structure of ,, diameter of fibres, 31 ,, serrations on, 31 ,, Leicestershire, 31 ,, Saxony, 31 Wrap reel, 115 Yarn tester, 116 ,, ,, adjustment of, 119 Palmer and Howe, Printers, Princess Street, Manchester. 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