Part 1 (2/2)
Chlorine and bleaching-powder solutions soon attack and destroy silk, and so another and ent, namely, sulphurous acid, is used to bleach this fibre Silk is easily dyed by the aniline and coal-tar colours, and with beautiful effect, but it has little attraction for the mineral colours
_Wool_--Next to silk as an animal fibre we co certain classes of anioats, rabbits, and hares Generally, and without going at all deeply into the subject, we may say that wool differs froard it as a variety, by being usually more elastic, flexible, and curly, and because it possesses certain features of surface structure which confer upon it the property of being ether than fur and hair are We rowth of hair without spending too ure (see Fig 5) shows a section of the skin with a hair or wool fibre rooted in it Here we round work, if wedoards, we have--(first) the outer skin, scarf-skin or cuticle; (second) a second layer or skin called the _retethe epidermis; (third) papillary layer; (fourth) the coriulobular, cellular masses below in the corium are called adipose cells, and these throw off perspiration or lands shown (called sudoriparous glands), which, as is seen, pass independently off to the surface Other glands terminate under the skin in the hair follicles, which follicles or hair sockets contain or enclose the hair roots These glands ter in the hair follicles secrete an oily substance, which bathes and lubricates as well as nourishes the hair
With respect to the origin of the hair or wool fibre, this is for therefroradually becorowth proceeds, are elongated into fibres, which form the central portion of the hair Just as with the trunk of a tree, we have an outer dense portion, the bark, an inner less dense and more cellular layer, and an inmost portion which is most cellular and porous; so with a hair, the central portion is loose and porous, the outer6) of the longitudinal section of a human hair, we see first the outer portion, like the bark of a tree, consisting of a dense sheath of flattened scales, then co of closely-packed fibrous cells, and frequently an inner well- a7) shows this exceedingly well The end of a hair is generally pointed, soer than the shaft, and terminates in a conical bulb, or mass of cells, which for 8) we are supposed to have separated these cells, and above, (a), we see solobules; between, (b), soular cells; and below, (c), two flattened, compressed, structureless, and horny scales from the outer portion of the hair Now these latter flattened scales are of great importance
Their character and mode of connection with the stratum, or cortical substance, below, not only make all the difference betool and hair, but also deterree of that peculiar property of interlocking of the hairs known as felting Let us now again look at a huht was reflected from this hair as it lay under the e in the longitudinal section, for just as the tiles lie on the roof of a house, or the scales on the back of a fish, so the whole surface of the hair is externally coated with a fir scales, with not very even upper edges, as you see The upper or free edges of these scales are all directed towards the end of the hair, and away from the root But when you look at a hair in its natural state you cannot see these scales, so flat do they lie on the hair-shaft What you see are only irregular transverse lines across it Now I coreat importance, as will later on appear in connection withproperties If a hair such as described, with the scales lying flat on the shaft, be treated with certain substances or reagents which act upon and dissolve, or decoes of these scales rise up, they ”set their backs up,” so to say They, in fact, stand off like the scales of a fir-cone, and at length act like the fir-cone in ripening, at last becoards wool and fur, these scales are of the utmost importance, for very le sheep, or the fur of a single hare It is the duty of the wool-sorter to distinguish and separate the various qualities in each fleece, and of the furrier to do the same in the case of each fur
In short, upon the nature and arrangement and conforards those free upper edges, depends the distinction of the value of many classes of wool and fur
These scales vary both as to nature and arrangement in the case of the hairs of different animals, so that by the aid of thefrom what kind of animal the hair has been derived It is on the nature of this outside scaly covering of the shaft, and in the manner of attachment of these scaly plates, that the true distinction betool and hair rests The principal epidermal characteristic of a true wool is the capacity of its fibres to felt or reater looseness of the scaly covering of the hair, so that when opposing hairs co 9), and thus the fibres are held together
Just as with hair, the scales of which have their free edges pointing upwards away from the root, and towards the extremity of the hair, so ool When the wool is on the back of the sheep, the scales of the woolly hair all point in the same direction, so that while maintained in that attitude the individual hairs slide over one another, and do not tend to felt or mat; if they did, woe betide the animal The fact of the peculiar serrated, scaly structure of hair and wool is easily proved by working a hair between the fingers If, for instance, a huently rubbed by the alternate ether, it will then invariably move in the direction of the root, quite independently of the will of the person perforlance at the for 10), will show the considerable difference between a wool and a hair fibre You will observe that the scales of the wool fibre are rather pointed than rounded at their free edges, and that at intervals we have a kind of co into each other, and thusof the cylindrical portion of the fibre The sharpened, jagged edges enable these scalesscales, and to penetrate inwards and doards according to the pressure exerted The free edges of the scales of wool are er and deeper than in the case of hair In hair the overlapping scales are attached to the under layer up to the edges of those scales, and at this extreents But this is not so ool, for here the ends of the scales are, for nearly two-thirds of their length, free, and are, moreover, partially turned outwards One of the fibres shown in Fig 10 is that of the merino sheep, and is one of the rown There you have the type of a fibre best suited for textile purposes, and the more closely different hairs approach this, the more suitable and valuable they becoard to the curly structure of wool, which increases the h the true cause of this curl is not known, there appears to be a close relationshi+p between the tendency to curl, the fineness of the fibre, and the nuard to hair and fur, I have already shown that serrated fibres are not specially peculiar to sheep, but are herof soer nurowth of fine woolly fibre, especially in the winter tienerally, froher to the lower fore the different parts of the fibre, as well as in a greater or less develop or external hair surface
Thus, under the microscope, the wool and hairs of various animals, as also even hairs froreat variety of structure, development, and appearance
[Illustration: FIG 5]
[Illustration: FIG 6]
[Illustration: FIG 7]
[Illustration: FIG 8]
[Illustration: FIG 9]
[Illustration:
Finest merino wool fibre
Typical wool fibre
Fibre of wool from Chinese sheep
FIG 10]
[Illustration: FIG 11]
[Illustration: FIG 12]
We have already observed that hair, if needed for felting, is all the better--provided, of course, no injury is done to the fibre itself--for so flatter on the hair-shafts than in the case of the hairs of wool, are es This brings me to the consideration of a practice pursued by furriers for this purpose, and known as the _secretage_ or ”carrotting” process; it consists in a treatment with a solution of mercuric nitrate in nitric acid, in order to i qualities of the fur This acid mixture is brushed on to the fur, which is cut fro ave me specimens of some fur untreated by the process, and also some of the same fur that had been treated, informed me that others of his line of business use more mercury than he does, _ie_ leave less free nitric acid in their mixture; but he prefers his own method, and thinks it answers best for the proave me was turned yelloith the nitric acid, in parts brown, and here and there the hairs were slightly matted with the acid In my opinion the furacid, and in the final process of finishi+ng I should not be surprised if difficulty were found in getting a high degree of lustre and finish upon hairs thus roughened or partially disintegrated Figs 11 and 12 respectively illustrate fur fibres from different parts of the sa one of these fibres frohness is, and what is also the cause of the difficulty in giving a polish or finish The free edges are partially disintegrated, etched as it were, besides being caused to stand out A weaker acid ought to be used, or more mercury and less acid As we shall afterwards see, another dangerous agent, if not carefully used, is bi+chrome (bi+chrohen and injure the fibre, and thus interfere with the final production of a good finish
LECTURE II
TEXTILE FIBRES, PRINcipaLLY WOOL, FUR, AND HAIR--_Continued_
With regard to the preparation of fur by acid , mentioned in the last lecture, I will tell you what I think I should recorease, and this may vary in different parts of the material Where there is most, however, the acid, nitric acid, or nitric acid solution of nitrate of mercury, et, and so act on the fur, least But the action ought to be uniforrease is removed I should therefore first wash the felts on the fur side with a weak alkaline solution, one of carbonate of soda, free frorease, then ater to remove alkali; and my belief is that a weaker and less acid solution of nitric acid and nitrate of mercury, and a smaller quantity of it, would then do the work required, and do it more uniformly
A question frequently asked is: ”Why will dead wool not felt?” Answer: If the aniradation; also, with improvement in health follows _pari passu_, improvement in the wool structure, which our of the scales on the wool fibres, increase of the serrated ends of these, and of their regularity In weakness and disease the nuiven hair-shaft diminishes, and these become finer and less pronounced The fibres themselves also become attenuated Hence when disease becoraded fibres This is seen clearly in the subjoined figures (see Fig 13), which are of wool fibres from animals that have died of disease The fibres are attenuated and irregular, the scale es have alenerally scanty and re in development It is no wonder that such ”dead wool” will be badly adapted for felting ”Dead wool” is nearly as bad as ”kempy” wool, in which malformation of fibre has occurred In such ”kemps,” as Dr Bowman has shown, scales have disappeared, and the fibre has become, in part or whole, a dense, non-cellular structure, resisting dye-penetration and felting (see Fig
14)