118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13. The Fnraday Society is not vespoztsible for opinions extressed before i t by Authors or Speakers.transactions Chc Sarabap 5ocietp. OF FOUNDED 1903. T O PROMOTE THE STUDY OF ELECTROCHEMISTRY, ELECTROMETALLURQY, CHEMICAL PHYSICS, METALLOGRAPHY, AND KINDRED SUBJECTS. VOL. xx. DECEMBER, I 924. PART 2. PHYSICAL AND PHYSICO-CHEMICAL PROBLEMS RELATING TO TEXTILE FIBRES. A GENERAL DISCUSSION. A joint meeting of the FARADAY SOCIETY and the TEXTILE INSTITUTE was held at the British Empire Exhibition, Wembley, on Wednesday, June I Ith, 1924, when a GENERAL DISCUSSION took place on ( ( PHYSICAL AND PHYSICO-CHEMICAL PROBLEMS RELATING TO TEXTILE FIBRES” PART I. Chairman :-Sir Robert Robertson, K.B.E., F. R.S., President of the Faraday Society. Dr. W. Lawrence Balls, Sc.D., F.S.S. (The Fine Cotton Spinners’ and Doublers’ Association), delivered the following In- troduction to the proceedings.Received May 2 7 th, I 9 2 4. The field of physical research in relation to the textile industries is sharply demarcated into two portions-one dealing with the physical pro- perties of the unit components of the textile, the other dealing with the inter-relationships between these components. (a) PhyszcaZ Prujerties of fhe TexfiCe Unit.-The unit from the textile point of view may be taken as the single hair or fibre, the question as to the nature of the unit in the physical sense being put aside by stating that it must necessarily be the atom.2 24 PHYSICAL AND PHYSICO-CHEMICAL PROBLEMS Study of the physics of these textile units is necessarily closely coupled with biology; and this to a greater extent than is commonly recognised, since nearly all the fibres and hairs employed in textile work are of plant or animal origin. The physical properties of such hairs and fibres largely depend on their growth history, and are more easily understood if this is studied concurrently. In illustration we may quote the case of cotton, which was formerly regarded as impure cellulose ; then as a cell wall ; then as a colloid ; and now as a structure which includes all the previous de- scriptions.One might insist on the importance of working with single units in the study of these properties, and not merely with masses of units, though the importance of “ single hair ” technique is more generally realised than it used to be. As a consequence of this, there develops the need for statistical treatment throughout by which to evaluate the nature and degree of variability from unit to unit.(b) Inter-reZationsh$ of the Unit Components.-We are not aware that any attempt has previously been made to generalise the peculiar form which physical problems take in this field. For convenience we may formulate the position, with some exaggeration, as follows : That one dimensional units (hairs and fibres) are built up into two dimensional structures (yarns and fabrics) for use in three dimensions. The study of such a system of inter-related units would appear to fall into a study of its statics and dynamics ; but it is doubtful whether any strictly static treatment is possible with the existing textiles. The “ creep ” displayed as between one unit and another of the complex, together with the ‘‘ set ” that individual units undergo, practically prohibits anything more than first approximations being obtained on static considerations.For ex- ample we may take a case where the tensile strength of yarn is unaffected by variations up to 2000-fold in the length tested. Or we may take, again, the fact that it is possible to eliminate some of the twist from a strand of yarn, although both ends remain firmly clamped, and are restored to their original position. It would seem that the dynamic treatment of the subject must be ap- plied at every point, in lap or sliver, yarn or cloth. Such treatment is par- ticularly important industrially in the attempt to obtain even distribution of the units in the drafting process.This process, it should be noted, is fundamental to every textile industry (other than silk and artificial silk), whether it is effected by hand or by the roller motion invented by Wyatt in 1745. If we imagine ourselves viewing the oncoming sliver as it is being drafted, it consists of a set of points; but these points paradoxically have each an enormous surface. There is no parallel outside the textile indus- tries to the class of phenomena produced by this exaggeration of the properties of the material in one direction only. The writer proposed the term ‘‘ Trichodynamics ” in 1918, on the analogy of Aerodynamics, to indicate this peculiar field of study. ConcZusion.-The defects of yarn and fabrics which admittedly exist, together with other defects whose existence is not even recognised, were formerly due to faults in the machinery employed.Many of these have been eliminated in the course of time ; and the physicist is now concerned rather with studying the causation of defects which are inherent in the pro- perties of the raw material. The utility of the scientist in industry is largely conditioned by the degree of stability of the industry; and where conditions, methods, and objects are changing-as they appear to be tending to change in textiles-the slow translation of experience by the225 RELATING TO TEXTILE FIBRES practical man lags behind the rate of advance required. Rapid accumula- tion of knowledge can only be made by experiments carried to the reductio ad absurdurn in all directions. In the course of some additional comments, Dr.Balls said he had been interested to find that practically every paper to be read at this meeting dealt with the first of the two halves into which he had divided the field to be covered, viz., the properties of the fibres themselves. I t was the second part of the subject, however, which was the most complicated, and offered the most difficult field for study, a field which was peculiar to textiles and was still practically untouched. As regards the first part, during ten years’ experience in the cotton industry, and ten more in cotton growing, he had often seen the beneficial effect of a little dose of biology here and there, and the manner in which it helped non-biologists to get round corners where otherwise they would have been stuck for a very long while.The point which he wished to impress in this connection was that the properties of the textile unit could not be tackled without dealing with its previous history, i.e. with the growth of the composite structure. In the case of cotton that had been a very marked feature indeed, and it happened that cotton was now the best known of all units from this point of view. The second part of the field for investigation appeared when one left the study of the individual unit and turned to the inter-relationships of the various units building up the yarn or fabric, and that was almost an unexplored field. I t was, however, an aspect fundamental to the textile industries and, in a sense, the thing making the textile industries worth the attention of the physicist. From the scientific point of view there was the most wonderful material for study in the inter-relationships of these peculiar units.When one started to examine the properties of fabrics or yams all sorts of aberrations were immediately found. On the idea of the strength of the chain being in its weakest link, one would imagine that the testing of a longer Iength of yarn (at the same rate of loading) would give a greater chance of discovering the weaker links and also give a measure of the frequency of occurrence of the weaker links in the chain. Most of them, however, probably knew that that was not the case. There was one extreme instance within his experience in which the length of the thread had been varied from 10 cm. to 12,000 cm. and the breaking load had remained unaffected.That, of course, was an extreme case but it de- monstrated the fact that rigid reasoning was not applicable and that there were a good many more variables in the proposition than was commonly supposed. Most of the faults in cotton yarns to-day were faults intrinsic in the physical properties of the raw materials (ie. in the textile units themselves) rather than faults in machinery and things of that character ; the difficulty was to locate these properties in the raw material and measure them. When an industry was changing its technique, as the electrical industry always was and the textile industry was now beginning to do, the scientist’s place was very different from what it was in a stable industry, and the main reason why a scientist could be useful to an unstable industry-an industry which was going through a process of change or evolution-was that the practical man took a very long time to get the answer in ex- perimental work.The scientist was trained in experimental work and he ought to be able to get his answer more quickly (so that was nothing226 PROBLEMS RELATING TO TEXTILE FIBRES to his credit), but the chief reason for the slowness of the practical man in getting at the answer was that he was always afraid to experiment off the deep end, and would not try the reductio ad absurdurn. He would put in one per cent. more twist or 2 per cent. more t*ist and, perhaps, take three or four years to feel his way to the final result. On the other hand, the scientist given the same problem, who did not know the kind of twist he should use, would try the experiment to the extreme in both directions at the first attempt. To use a gunner’s term, he would quickly straddle the final result. On the assumption that the textile industry was in for a series of changes, not only had the physicist an extremely interesting field to explore in which he could be of use to the industry but, in course of time, the industry would find that his services were indispensable. In conclusion, Dr. Balls said it was a great pleasure to him to open the discussion because in the early days of the Research Associations, and even sooner, he had backed physics as the winning horse for industrial research in the textile industry. He had come long ago to the decision quite definitely, that the pivotal subject for industrial research in the textile industries during the next half century was that child of the Cavendish Laboratory, and outcast of practical men, the study of physics.