Dyeing is the art of giving colour to textile and other articles in such a way that the colours are more or less permanent, and not readily affected by the action of light, washing, etc. Like spinning and weaving it was originally a home industry, as it still is in many places. Until about 1850 natural dye-stuffs alone were employed, but the discovery of dyes of all colours that can be obtained from coal-tar products revolutionized dyeing as an industry, and the vegetable dye-stuffs were gradually superseded by the newer colours.
Before dyeing, the materials have generally to be cleansed or bleached to get rid of undesirable colouring matters or impurities; and frequently a textile material is subjected to some subsidiary treatment in order to obtain special effects. For example, cottonyarn may be subjected to the action of strong causticsoda ('mercerizing' process) while in a state of great tension, in order to give it a permanent silky lustre.
Dyeing is not only an art, it is also a branch of applied chemistry. One fundamental principle is, that the colouring matter and other necessary substances must be applied in a state of solution, and while in direct contact with the fibre they must be rendered insoluble, so that they are precipitated within or upon the fibre and thus permanently fixed. The method of effecting this varies greatly according to the fibre and the colouring matter employed. As a rule the vegetable and the animal fibres are dyed by very different methods. The affinity of the animal fibres for certain colouring matters is often so great that they are readily dyed by simple immersion in hot colour solutions;
but this simple process is not generally sufficient. According to the method of their application in dyeing the following groups: of dye-stuffs may be distinguished: Avid Colours, Basic Colours, Direct Colours, Developed Colours, Mordant Colours, Miscellaneous Colours, Reactive Colours.
The acid colours are so called because they are of an acid character and are applied in an acid dye-bath. As a rule, they are only suitable for dyeing the animal fibres, e.g. wool and silk, also leather, horn, feathers, etc. Only a few vegetable dye-stuffs belong to this class, for example, the purple colour orchil and the blue colour indigo extract. On the other hand, the acid colours derived from coal-tar - and increasingly petroleum - are very numerous and yield a great variety of hues - red, orange, yellow, green, blue, violet, brown, and black, each with its particular name.
The basic colours are so called because their essential constituents, to which they owe their dyeing power, are organicbases. The bases themselves are colourless and too insoluble in water to be of use, hence they are employed in the form of their soluble coloured salts, usually the hydrochlorides of the colour-bases. Their solutions are precipitated by tannic acid, because it combines with the colour-bases to form insoluble tannates. Wool, silk, and animal substances generally have a direct attraction for colour-bases, and hence these fibres are readily dyed by simple immersion in hot aqueous solutions of the basic colours. Cotton and linen, on the other hand, are not dyed so readily; they need first to be prepared or impregnated with tannic acid, and thus prepared are said to be mordanted, the tannic acid in this connection being styled the mordant. Most of the colours of this class are fugitive to light, and all but one, barberryroot, are derived from coal-tar products.
The direct colours are so called because they dyecotton direct, that is, without the aid of any mordanting process. The first of this class derived from coal-tar was congo red, discovered in 1884; this group includes a very great variety of fast colours, and forms, indeed, one of the most important and valuable series of dye-stuffs employed. Cotton, linen, and the vegetable fibres generally are dyed in the simplest possible manner by merely boiling them in a solution of the dye-stuff, with or without the addition of a little soap, carbonate or sulphate of soda, etc. Wool and silk are frequently dyed in the same manner as cotton. Very few vegetable dye-stuffs belong to the direct colours, e.g. Safflower, Turmeric, Saffron, Annatto. They are all fugitive, and have been of little or no importance to the dyer since the end of the 19th century. The coal-tar colours of this class, on the other hand, are extremely numerous.
The developed colours include a variety of colours which are formed in situ upon the fibre by the successive application of two or more substances. These colours are all of coal-tar origin. A number of them belong to the so-called azo colours, derived from compounds containing nitrogen.
The mordant colours form one of the most important classes of colouring matters, for they include not only most of the vegetable dye-stuffs, e.g. madder, logwood, fustic, etc, but also many valuable fast coal-tar colours, commonly known as the alizarin colours, after their typical representative, alizarin. These mordant colours have by themselves very little colouring power, as a rule, and if employed alone in dyeing give little or no result. If applied, however, in conjunction with metallic salts, notably those of chromium, aluminium, iron, tin, and copper, they each yield a variety of colours, according to the metallic salt employed. In employing them usually two distinct operations are involved: first, that of applying the metallic salt or mordant, called the mordanting process ; and second, that of dyeing proper, in which the mordanted material is boiled in a solution or decoction of the dye-stuff. During the dyeing operation the colouring principle of the dye-stuff combines with the metallic salt already upon the material, and the colour is thus produced and fixed upon the fibre. The method of mordanting varies with the fibre and the metallic salt employed. The vegetable dye-stuffs of this class include Madder, Sapanwood, Camwood, Barwood, Old Fustic, Young Fustic, Quercitron Bark, Persian Berries, Weld, Logwood. Madder was formerly the most important and highly valued of the dye-stuffs of this class, being especially employed to produce the fine 'Turkey-red' dye; but was entirely superseded by the coal-tar colour alizarin towards the end of the 19th century.
Reactive colours combine directly with the fibre being dyed through a chemical reaction and result in a fast colour. The first ranges of reactive dyes for cellulose fibres were introduced in the mid-1950s.
Similarly, the employment of cochineal (an insect dye) has also greatly diminished through the introduction of the cheaper colours. Camwood and barwood are almost entirely used in wool-dyeing, either in conjunction with the indigo-vat or for the purpose of dyeing various shades of brown. Old fustic is the most important of the yellow mordant dye-stuffs, and the colours are fast although not very brilliant. Young fustic yields fugitive colours, and has been little used since 1900. Quercitron bark is an excellent dye-stuff employed by wool-dyers for the production of bright orange and yellow colours. Persian berries and weld, a species of wild mignonette, are both excellent dye-stuffs, but their employment is now limited. Logwood is largely employed by wool, silk, and cotton dyers for dyeing black and dark-blues, which, although fast to washing, are only moderately so towards light. During the 20th century dyewoods were gradually replaced by coal-tar colours.
Among miscellaneous colours are several dye-stuffs applied in a distinct manner. Indigo is a dark-blue powder quite insoluble in water, but can be rendered soluble for dyeing purposes by two methods. The first method converts the indigo into so-called indigo extract, which is sold as a blue paste and applied as an acid colour in dyeing wool and silk. In the second method the indigo-blue is converted into indigo-white, which readily dissolves in the alkalipresent, the solution thus obtained being called an indigo-vat. If cotton, wool, or silk is steeped for some time in the clear yellow solution of such a vat, and then exposed to the oxidizing influence of the air, they are dyed a permanent blue. The indigo-white absorbed by the fibre loses its acquired hydrogen, and thus insoluble indigo-blue is regenerated within and upon the fibre. Aniline black is a valuable colour, produced direct upon the fibre by the oxidation of aniline, and remarkable for its extreme permanency.
Catechu is a vegetable dye-stuff used in dyeing cotton and woollen brown. On wool, catechu yields khaki browns in single bath by using copper sulphate as the mordant. On silk it is largely employed for weighting purposes in the process of dyeing black. Chrome Yellow, Iron Buff, Prussian Blue, and Manganese Brown, employed in cotton dyeing, are frequently classed as mineral colours. Chrome yellow is obtained by immersing cotton successively in solutions of acetate of lead and bichromate of potash, whereby the yellow precipitate of chromate of lead is fixed upon the fibre. Iron buff is obtained in a similar manner by the successive application of iron sulphate and carbonate of soda, and finally developing the full colour by washing with water and exposure to air. The buff colour is really due to the precipitation of oxide of iron on the cotton. Prussian blue is at once developed by passing the buff-dyed cotton through an acidified solution of potassium ferrocyanide. The production of manganese brown on cotton is similar to that of iron buff. The brown colour ultimately produced upon the fibre is an oxide of manganese. The mineral colours are very useful for certain purposes, and are to be regarded as very fast to light. Research Dyeing
An animal is an organized and sentient living being. Life in the earlier periods of natural history was attributed almost exclusively to animals. With the progress of science, however, it was extended to plants. In the case of the higher animals and plants there is no difficulty in assigning the individual to one of the two great kingdoms of organic nature, but in their lowest manifestations, the vegetable and animal kingdoms are brought into such immediate contact that it becomes almost impossible to assign them precise limits, and to say with certainty where the one begins and the other ends. From form no absolute distinction can be fixed between animals and plants. Many animals, such as the sea-shrubs, sea-mats, etc, so resemble plants in external appearance that they were looked upon as such. With regard to internal structure no line of demarcation can be laid down, all plants and animals being, in this respect, fundamentally similar; that is, alike composed of molecular, cellular, and fibrous tissues. Neither are the chemical characters of animal and vegetable substances more distinct. Animals contain in their tissues and fluids a larger proportion of nitrogen than plants, whilst plants are richer in carbonaceous compounds than the former. In some animals, moreover, substances almost exclusively confined to plants are found. Thus the outer wall of Sea-squirts contains cellulose, a substance largely found in plant-tissues; whilst chlorophyll, the colouring-matter of plants, occurs in Hydra and many other lower animals.
Power of motion, again, though broadly distinctive of animals, cannot be said to be absolutely characteristic of them. Thus many animals, as oysters, sponges, corals, etc, in their mature condition are rooted or fixed, while the embryos of many plants, together with numerous fully developed forms, are endowed with locomotive power by means of vibratile, hair-like processes called cilia. The distinctive points between animals and plants which are most to be relied on are those derived from the nature and mode of assimilation of the food. Plants feed on inorganic matters, consisting of water, ammonia, carbonic acid, and mineral matters. They can only take in food which is presented to them in a liquid or gaseous state. The exceptions to these rules are found chiefly in the case of plants which live parasitically on other plants or on animals, in which cases the plant may be said to feed on organic matters, represented by the juices of their hosts. Animals, on the contrary, require organized matters for food. They feed either upon plants or upon other animals. But even carnivorous animals can be shown to be dependent upon plants for subsistence; since the animals upon which Carnivora prey are in their turn supported by plants. Animals, further, can subsist on solid food in addition to liquids and gases; but many animals (such as the Tapeworms) live by the mere imbibition of fluids which are absorbed by their tissues, such forms possessing no distinct digestive system.
Animals require a due supply of oxygen gas for their sustenance, this gas being used in respiration. Plants, on the contrary, require carbon dioxide. The animal exhales or gives out carbon dioxide as the part result of its tissue-waste, whilst the plant taking in this gas is enabled to decompose it into its constituent carbon and oxygen. The plant retains the former for the uses of its economy, and liberates the oxygen, which is thus restored to the atmosphere for the use of the animal. Animals receive their food into the interior of their bodies, and assimilation takes place in their internal surfaces. Plants, on the other hand, receive their food into their external surfaces, and assimilation is effected in the external parts, as are exemplified in the leaf-surfaces under the influence of sunlight. All animals possess a certain amount of heat or temperature which is necessary for the performance of vital action. The only classes of animals in which a constantly-elevated temperature is kept up are birds and mammals. The bodily heat of the former varies from 100 degrees Fahrenheit to 112 degrees Fahrenheit and of the latter from 96 degrees to 104 degrees. The mean or average heat of the human body is about 99 degrees Fahrenheit, and it never falls much below this in health. Below birds animals are named cold-blooded, this term meaning in its strictly physiological sense that their temperature is usually that of the medium in which they live, and that it varies with that of the surrounding medium, Warm-blooded animals, on the contrary, do not exhibit such variations, but mostly retain their normal temperature in any atmosphere. The cause of the evolution of heat in the animal body is referred to the union (by a process resembling ordinary combustion) of the carbon and hydrogen of the system with the oxygen taken in from the air in the process of respiration. Research Animal
Cellulose is the cellular tissue of plants. It is a member of the carbohydrate family and is allied to starch. In plants, cellulose is normally combined with woody, fatty, or gummy substances. With some exceptions among insects, true cellulose is not found in animal tissues. Microorganisms in the digestive tracts of herbivorous animals break down the cellulose into products that can then be absorbed.
Cellulose is insoluble in all ordinary solvents and may be readily separated from the other constituents of plants. Depending on its concentration, sulphuric acid acts on cellulose to produce glucose, soluble starch, or amyloid; the last is a form of starch used for the coating of parchment paper. When cellulose is treated with an alkali and then exposed to the fumes of carbon disulphide, the solution yields films and threads. Rayon and cellophane are cellulose regenerated from such solutions.
Cellulose acetates are spun into fine filaments for the manufacture of some fabrics and are also used for photographic safety film, as a substitute for glass, for the manufacture of safety glass, and as a moulding material. Cellulose ethers are used in paper sizings, adhesives, soaps, and synthetic resins. With mixtures of nitric and sulphuric acids, cellulose forms a series of flammable and explosive compounds known as cellulose nitrates, or nitrocelluloses. Pyroxylin, also called collodion cotton, is a nitrate used in various lacquers and plastics; another, collodion, is used in medicine, photography, and the manufacture of artificial leather and some lacquers. A third nitrate, guncotton, is a high explosive. Research Cellulose
Chitin is a hard, cellulose-like compound that constitutes much of the exoskeleton of various arthropods such as crustaceans and insects. Strong and firm, the substance serves to support the body tissues of such organisms. Research Chitin
In botany, duramen is the name given to the central wood or heart-wood in the trunk of an exogenous tree. It is more solid than the newer wood that surrounds it, from the formation of secondary layers of cellulose in the wood cells. Research Duramen
Fungi is a large family of cryptogamous life form, neither animal nor plant, but a separate classification. Fungi agree with algae and lichens in their cellular structure, which is, with few exceptions, devoid of anything resembling vascular tissue; but differing from them in deriving their nutrition from the body on which the grow, not from the medium by which they are surrounded. Fungi are distinct from plants in not containing any cellulose in their structure; all plants contain cellulose in their cells. Research Fungi
Nutrition is the strategy adopted by an organism to obtain the chemicals it needs to live, grow, and reproduce. The term is also applied to the science of food, and its effect on human and animal life, health, and disease.
Nutrition involves the study of the basic nutrients required to sustain life, their bio-availability in foods and overall diet, and the effects upon them of cooking and storage. It is also concerned with dietary deficiency diseases. There are six classes of nutrients: water, carbohydrates, proteins, fats, vitamins, and minerals. Water is involved in nearly every body process. Animals and humans will succumb to water deprivation sooner than to starvation. Carbohydrates are composed of carbon, hydrogen and oxygen. The major groups are starches, sugars, and cellulose and related material (or ' roughage'). The prime function of the carbohydrates is to provide energy for the body; they also serve as efficient sources of glucose, which the body requires for brain functioning, utilisation of foods, maintenance of body temperature. Roughage includes the stiff structural materials of vegetables, fruits, and cereal products. Proteins are made up of smaller units, amino acids. The primary function of dietary protein is to provide the amino acids
required for growth and maintenance of body tissues. Both vegetable and animal foods are protein sources. Fats serve as concentrated sources of energy, and protect vital organs such as the kidneys and skeleton. Saturated fats derive primarily from animal sources; unsaturated fats from vegetable sources such as nuts and seeds. Vitamins are essential for normal growth, and are either fat-soluble or water-soluble. Fat-soluble vitamins include A, essential to the maintenance of mucous membranes, particularly the conjunctiva of the eyes; D, important to the absorption of calcium; E, an antioxidant; and K, which aids blood clotting. Water-soluble vitamins are the B complex, essential to metabolic reactions, and C, for maintaining connective tissue and cell functioning. Minerals are vital to normal development; calcium and iron are particularly important as they are required in relatively large amounts. Minerals required by the body in trace amounts include chromium, copper, fluoride, iodine, iron, magnesium, manganese, molybdenum, phosphorus, potassium, selenium, sodium, and zinc. Research Nutrition
Xeris is a genus of Horntail (Siricidea). Xeris spectrum is a mostly black species with yellow spots on the sides of the prothorax, and partly yellowish-red legs. The female is armed with a long ovipositor, but is actually harmless to man, the ovipostor serving only for laying eggs. Xeris spectrum is distributed over most of Europe, Siberia, China and Japan and is between 15 and 30 mm long. They are mostly found in pine woods where the adults fly on warm, sunny days. The larvae feed on the cellulose of wood, taking between two and three years to develop, and are often introduced into buildings through timber. Research Xeris
Colostomy is the operation of opening into the colon, or lower portion of the intestine. This procedure is one of the most important in abdominal surgery. It is sometimes necessary as a life- saving measure. It may be temporary or permanent as an artificial anus in the radical treatment of rectal cancer. Because of its appearance, its inconvenience and the very thought of an artificial opening in the abdominal wall a great deal of care is necessary to allay the anxieties of patients and their relatives when colostomy is necessary.
In some cases of acute intestinal obstruction the surgeon explores the abdomen and finds perhaps a large mass in the region of the pelvic colon or rectum that cannot be removed. An emergency colostomy is then performed in the transverse colon with the immediate purpose of saving life and with the further objective of providing temporary drainage should the growth be removable at a later date. In some such cases, when at first sight the primary cause of the obstruction seems beyond any possibility of surgical removal, after several weeks of colostomy drainage the infection subsides and the affected portion of bowel may then be removed. Colostomy may be necessary as a preliminary to other operations involving removal of the large bowel. Such an occasion arises if diverticulitis has produced vesico-colic fistula (between the colon and bladder). In some cases of severe incontinence due to abnormality or injury to the anus, a left iliac colostomy enables the patient to be free of the terrible inconvenience of perpetual soiling in the perineum. Injuries or abnormalities of the spinal cord produce paralysis of the anal sphincter mechanism and sometimes colostomy is essential. Congenital absence of the rectum or anus requires an emergency colostomy within a day or so of birth.
There are two main forms of colostomy. First is the loop colostomy which has two limbs. The opening is at the apex of the loop and the bowel has not been divided completely across. A variation of the loop colostomy is the double- barrel form in which the two limbs of the loop are separated by a piece of skinrafter complete division. This is also described as a defunctioning colostomy as it prevents the spill of faeces from the proximal to the distalloop. A second variety is the spur colostomy where a spur is formed by suturing the two ends together for several centimeters inside the abdomen. This is of particular value if the colostomy is temporary as the spur can be destroyed by a crushing clamp without risk of peritonitis or perforation since the limbs have become sealed together. When the spur breaks down, the artificial opening on the surface shrinks and sinks back below the skin level. The aim is that this should close spontaneously without further operation. The third type is the terminal colostomy in which the distal portion of bowel is removed completely or in the case of excision of rectum the lower end is closed to form a blind end. In grave emergencies the simplest form of colostomy is performed in which a loop of colon is brought out through the abdominal wall, where it is held by the insertion of a glassrod passed through a small hole in the mesentery. The ends of the glassrod are connected by a loop of rubber tubing which forms a 'bucket handle' . The abdominal wall is closed around the protrusion of the colostomy. Exteriorisation is another way of performing a colostomy. If a growth is present in a part of the bowel which can be brought readily through the abdominal wall (e.g. transverse or pelvic colon) the affected loop containing the growth is left outside and the peritoneum, muscles and skin are closed around the base of the loop where the two limbs converge. The loop of colon containing the growth is then removed, leaving two open ends of el which can later be joined by crushing the spur between them. This operation avoids the handling of growth or unprepared bowel while the peritoneal cavity is open and so diminishes the risk of peritonitis. A formal operation for closure is required if a spur has not been made.
At the end of the operation a small incision is usually made in the apex of the loop to allow the immediate discharge of gas and faecal material which is collected as cleanly as possible before the patient leaves the theatre. A dressing of petroleum jelly gauze or tullegras is applied on the exposed bowel. The skin incision may be sealed with Whitehead's varnish and a pad of cellulosetissue and wool is bandaged lightly over the opening. For fear of contaminating the abdominal wound before the peritoneal cavity has become sealed, the former practice was to leave the colostomy unopened for 48 hours. The initial opening may be enlarged by the surgeon two or three days after the colostomy has been raised. The bowel is usually divided (without anaesthetic) by an electric cautery which seals the blood vessels and prevents bleeding from the very vascular mucousmembrane and muscle wall of the bowel. A method of draining the colostomy is by the use of Paul's tube. This is an angled wide glass tube which is inserted through a hole in the colostomy loop. It is tied in position in the same way as the caecostomy catheter and connected to a bedside jar with wide, thin, latex tubing. Research Colostomy
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Dyeing
