Petersburgh, by a canal which joins it to the river Louat, and is navigable throughout. DWINA, another large river of Russia, is formed by the union of the Juchona and Jug, near the town of Ustjug, in the government of Vologda. It falls, by two arms, into the White Sea, a little to the north-west of Archangel, and is a broad and deep stream, but its mouths are choked with mud. DWIN'DLE, v. n. DWIN'DLED, adj. Sax. dwinan; Dut, dwynen; Isl. dwyna. To decay; to shrink; wear away; degenerate: as an active verb, to make less; to break down, or into parts; disperse. Weary sev'nnights nine times nine, Shakspeare. Macbeth. Under Greenvil, there were only five hundred foot and three hundred horse left; the rest were dwindled away. Clarendon. Thy dwindled legs seem crawling to the grave. Dryden. We see, that some small part of the foot being injured by a wrench or a blow, the whole leg or thigh thereby loses its strength and nourishment, and dwindles away. Locke. If there have been such a gradual diminution of the generative faculty of the earth, that ic hath dwindled from nobler animals to puny mice and insects, why was there not the like decay in the production of vegetables? Bentley. He found the expected council was dwindling into a conventicle, a packed assembly of Italian bishops, not a free convention of fathers. Atterbury. Our drooping days are dwindled down to nought, Their period finished ere 't is well begun. Thomson. Lost in thoughtless ease and empty show, Behold the warrior dwindled to a beau; Since freedom, piety, refined away, and Of France the mimick, and of Spain the prey. Johnson. London. In its preventive police it ought to be sparing of its efforts, and to employ means, rather few, unfrequent, strong, than many, and frequent, and, of course, as they multiply their puny politic race, and dwindle, small and feeble. Burke. Will they thank the noble lord for reminding us how soon these lofty professions dwindled into little jobbing pursuits for followers and dependants, as unfit to fill the offices procured for them, as the offices themselves were unfit to be created. Sheridan. DYE, v. a. & n. s. DYER, n. s. DYE'ING. DYEING. Sax. deagan, to color. Often written die. To tinge; color; stain. His looke was sterne, and seemed still to threat Cruell revenge, which he in hart did hyde, And on his shield Sansloy in blood lines was dyde. Spenser. Faerie Queene. It will help me nothing To plead mine innocence; for that die is on me, Which makes my whit'st part black. Shakspeare. Henry VIII. We have dainty works of feathers of wonderful lustre, excellent dies, and many. Bacon's New Atlantis. So much of death her thoughts Had entertained, as died her cheeks with pale. 1. Dyeing is a chemical art which has for its object the extracting of the coloring particles from such substances as afford them, and transferring them to certain stuffs of wool, silk, cotton, or linen. No art has profited so much from the improvements of modern chemistry as the art of dyeing has; and it cannot be, nor ought it to be forgotten, that while we owe much to the discoveries of our own countrymen, and the application of those discoveries to the useful arts, the art of dyeing is highly indebted to the national operations of the French chemists. 2. The origin of this art seems to be of high antiquity; a circumstance which renders it impossible to say to whom or to what it is to be attributed conjecture, therefore, is all we can pretend to. As most of the materials from which coloring matter is derived are, of themselves, either of dark and disagreeable colors, or else destitute of any particular color, it is probable that, even in the very earliest ages, the love of ornament, which is natural to mankind, and which is founded on the love of distinction, one of the most active principles of the human mind, would induce them to stain their vestments with various coloring ingredients, especially with vegetable juices But the means of imparting permanent dyes to cloth, and affixing to its fibres such coloring materials, as could not easily be washed out by water, or be obliterated or greatly changed by the action of air, or of certain saline substances, to which they are liable to be exposed, and which are necessary to render them clean when soiled, was an art which required the knowledge of principles not within the reach of untutored men, and only to be obtained by gradual investigation, and by the lapse of a considerable portion of time. 3. According to Pliny, the Egyptians had discovered a mode of dyeing, somewhat resembling that which we use for coloring printed linens: the stuffs, probably after having been impregnated with different mordants, were immersed in vats, where they received various colors. And M. Delaval is of opinion, that they were possessed not only of the art of dyeing, but even of that of printing on cloths. 4. The Phoenicians seem to have a strong claim to the invention of this art, and they held a decided pre-eminence in the practise of it for many ages their purple and scarlet cloths were sought after by every civilised nation; and the city of Tyre, enriched by its commerce, increased to an amazing extent. But her career was stopped by the vanity and folly of the eastern emperors; under whose dominion this opulent city had unfortunately fallen. Desirous of monopolising the wearing of the beautiful cloths of Tyre, these tyrants issued most severe edicts, prohibiting any one from appearing in the Tyrian blue, purple, or scarlet, except themselves, and their great officers of state. To this injudicious restriction is to be attributed the destruction of the Tyrian dyes. For under the impolitic restraint imposed on the consumption of the Phoenician cloths, the manufacturers and dyers were no longer able to carry on their trade; it grew languid and expired: and, with the trade, the art itself also perished. It is generally supposed from the name, that the Tyrian purple, so much celebrated among the ancients, was discovered at Tyre, and that it contributed not a little to the opulence of that celebrated city. The liquor which was employed in dyeing the purple was extracted from two kinds of shell-fish, one of which, the larger, was called the purple, and the other was a species of whelk. Each of these species was subdivided into different varieties, which were otherwise distinguished, according to the places where they were found, and as they yielded more or less of a beautiful color. It is in a vessel in the throat of the fish that the coloring liquor is found. Each fish only afforded a single drop. When a certain quantity of the liquor had been obtained, it was mixed with a proportion of common salt, macerated together for three days, and five times the quantity of water added. The mixture being kept in a moderate heat, the animal parts which happened to be mixed with it separated, and rose to the surface. At the end of ten days, when these opera tions were finished, a piece of white wool was immersed, by which means they ascertained whether the liquor had acquired the proper shade. Various processes were followed to prepare the stuff to receive the dye. By some it was immersed in lime-water, and by others it was prepared with a kind of fucus, which acted as a mordant to give it a more fixed color. Alkanet was used by some for the same purpose. The liquor of the whelk did not alone yield a durable color. The liquor from the other shell-fish served to increase its brightnesss; and thus two operations were in use to communicate this color. A first dye was given by the liquor of the purple, and a second by that of the whelk; from which it was called by Pliny purpura dibapha, or purple twice dipped. The small quantity of liquor which could be obtained from each shell-fish, and the tedious process of its preparation and application to the stuffs, raised the price of purple so high, that in the time of Augustus a pound of wool of the Tyrian purple dye, could not be purchased for one thousand denarii, equal to about £36 sterling. 5. Among the Greeks the knowledge of dyeing must have been very imperfect, and little assisted by science; for the art of dyeing linen appears not to have been known in Greece before Alexander's invasion of India, where, according to Pliny, they dyed the sails of his vessels of dif ferent colors. The Greeks seem to have borrowed this art from the Indians. 6. India seems to have been the nursery of the arts and sciences, which were afterwards spread and perfected among other nations. Accidents, which had a tendency to improve the art, could not fail to be multiplied rapidly, in a country, rich in natural productions; requiring little labor for the support of its inhabitants; and the popu lation of which was favored by the bounty of nature, and simplicity of manners, till it was opposed by the tyranny of succeeding conquerors. But religious prejudices, and the unalterable division into castes, soon shackled industry; the arts became stationary; and it would seem, that the knowledge of dyeing cotton in that country (for silk was then unknown, or at least very scarce) was as far advanced in the time of Alexander, as it is at the present period. 7. The beautiful colors, which are observable in some Indian linens, would lead one to suppose that the art of dyeing had there attained a high degree of perfection; but we find by the description which Beaulieu, at the request of Dufay, gave of some operations performed under his own eye, that the Indian processes are so complicated, tedious, and imperfect, that they would be impracticable in any other country, on account of the great difference in the price which is paid for labor. 8. It is unquestionably true, that European industry has far surpassed them in correctness of design, variety of shade, and facility of execution; and, if we are inferior to them with respect to the liveliness of some colors, it is only to be attributed to the superior quality of some of their dyes, or perhaps to the length and multiplicity of their operations and processes. In our own country, however, the art of dyeing made no considerable progress till about the beginning of the seventeenth century. Before that period our cloths were sent to Holland, to be dressed and dyed. This, however, was probably practised only in the case of particular colors. The dyeing of woollen and silken goods has indeed long since attained a considerable degree of excellence; but the manufactures of cotton, owing to the small attraction of that substance for coloring matters, have been very deficient in this point. Till within these few years, the colors employed in the dyeing of fustians and cotton velvets were few; and, even at this day, many of them are fugitive. But it must be allowed that great improvements have been made within these few years, from the application of chemical principles, and by a diligent investigation of the nature of coloring substances. There is however still much room for the improvement of the art, but this can only be effected by the practical dyer acquiring chemical knowledge, an acquisition now happily placed within the reach of every dyer who is capable of reading and understanding the English language. It will not be necessary for our present purpose to enter into a minute examination of the various theories that have been advanced of the nature of colors; at the same time it may be proper, before we deduce a general theory of dyeing, to make a few observations on the common properties of coloring substances. 9. In explaining the cause of color, and the nature of coloring particles, two great inconveniences have arisen. First, from an attempt to illustrate the action, which the particles of coloring substances have on the rays of light, in consequence of their density and thickness, without having any means of ascertaining this, and without any regard to the attractions which result from their chemical composition; in comparing the coloring particles to mucilages and resins, from some very faint resemblances; and in attempting to explain their coloring properties by conjectures, formed respecting their component parts, while these properties ought rather to be ascertained by direct experiment than explained by an imaginary composition. It was also departing from true theory, to ascribe to laws purely mechanical, the adhesion of the coloring particles to the substances dyed, the action of the mordants, the difference between the true or durable, and the false or fugitive dyes. 10. Hellot, who has written an excellent treatise on dyeing, seems to have erred on this subject; and Macquer, who was amongst the first who entertained just notions respecting chemical attractions, seems to have been led astray by his ideas. It appears, however, that Dufay had before observed, that the coloring particles were naturally disposed to adhere more or less firmly to the filaments which receive them; and had very justly remarked, that without this disposition, stuffs would never assume any color but that of the bath, and would always divide the coloring particles equally with it: whereas the liquor of the bath sometimes becomes as limpid as water, giving off all the coloring particles to the stuff; which, he observes, seems to indicate that the ingredients have less attraction for the water than for the particles of the wool. 11. Bergman seems to have been the first who referred the phenomena of dyeing entirely to chemical principles. Having dyed some wool and some silk in a solution of indigo, in very dilute sulphuric acid, he explains the effects he observed in the operation, by attributing them to the precipitation, occasioned by the blue particles having a greater affinity for the particles of the wool and silk, than for those of the acidulated water. He remarks that this affinity of the wool is so strong, as to deprive the liquor entirely of the coloring particles; but that the weaker affinity of the silk can only diminish the proportion of these particles in the bath, and he shows that on these different affinities depend both the permanence and intensity of the color. 12. This is the true light in which the phenomena of dyeing should be viewed; they are real chemical phenomena, which ought to be analysed in the same way as all those dependent on the actions which bodies exert, in consequence of their peculiar nature. It is evident, that the coloring particles of bodies possess che mical properties, that distinguish them from all other substances; and that they have attractions peculiar to themselves, by means of which they unite with acids, alkalis, metallic oxides, or calces, and some earths, principally alumine or pure clay. They frequently precipitate oxides and alumine, from the acids which held them in solution; at other times they unite with the salts, and form supercompounds which combine with the wool, silk, cotton, or linen. And with these their union is rendered much more close by means of alumine or metallic oxide, than it would be without their intermedium. 13. The difference in the affinity of the coloring particles for wool, silk, and cotton, is sometimes so great, that they will not unite with one of these substances, while they combine very readily with another; thus, cotton receives no color in a bath which dies wool scarlet. Dufay prepared a piece of stuff, the warp of which was wool and the woof cotton, which went through the process of fulling, that he might be certain, that the wool and the cotton received exactly the same preparation; but the wool took the scarlet dye, and the cotton remained white. It is this difference of affinity which renders it necessary to vary the preparation and the process, according to the nature of the substance which is intended to be dyed of a particular color. And these considerations ought to determine the means to be pursued for the improvement of the art of dyeing. It is highly proper to endeavour to ascertain what are the constituent principles of the coloring particles. And in this enquiry, the most essential circumstances are, to determine the affinities of a coloring substance; first, with the substances which may be employed as menstrua; secondly, with those which may, by their combinations, modify the color, increase its brilliancy, and help to strengthen its union with the stuff to be dyed; thirdly, with the different agents which may change the color, and priucipally with the external agents-air and light. 14. The qualities of the uncombined coloring particles are modified when they unite with a substance; and, if this compound unites with a stuff, it undergoes new modifications. Thus the properties of the coloring particles of cochineal are modified, by being combined with the oxide of tin, and those of the substances resulting from this combination are again modified by their union with the wool or silk; so that the knowledge we may acquire by the examination of coloring substances in their separate states, can only inform us respecting the preparations that may be made of them; that which we acquire respecting eir combinations with substances which serve to fix them, or to increase their beauty, may inform us what processes in dyeing ought to be preferred or tried; but it is only by direct experiment made with the different substances employed in dyeing, that we can confirm our conjectures, and properly establish the pro cess. 15. These facts show, that the changes produced by acids and alkalis on many vegetable colors, such as the chemists employ, in order to discover the nature of different substances, are owing to the combinations, which take place between these coloring particles and the acids and alkalis. The compounds resulting from these may be compared to neutral salts, which possess qualities different from those of their component parts, but in which one of these parts may be in excess, and its qualities consequently predominant. This state of combination is observable between the coloring particles of cochineal and acidulous tartrite of potassa, or cream of tartar: by evaporating slowly a solution of this salt in a decoction of cochineal, crystals are formed, which retain a fine ruby color, much more bright and intense than that of the liquor which formed them. 16. It was the opinion of Berthollet that some of the acids, particularly the nitric, after combining with the coloring particles, changed the color which they at first produced, making it yellow, and finally destroying it; after which they act by means of one of their principles, viz. the oxygen. But this theory, Dr. Ure remarks, is not now tenable, since it is known that dry chlorine does not blanch dry litmus paper. When moisture intervenes, muriatic acid is formed, and oxygen evolved; to the action of which body on the color the bleaching effect is to be ascribed. Water is the source of the discoloration, both in the ancient and modern process of bleaching. Blue colors are not the only ones which become red by the addition of acids, and green by that of alkalis; most red colors, as that of the rose, for instance, are heightened by acids, and made green by alkalis; and some green colors, such as that of the green decoction of burdock, according to the experiments of Mr. Nose, and the green juice of Buckthorn, as is evident from the trials of Mr. Becker, are reddened by acids. 17. This property, which is common to most of the ordinary colors of vegetables, seems to prove that there is a close analogy between their coloring particles; and it is not without foundation, that Linnæus supposed, that the red in vegetables was owing to an acid, and indicated its presence; but there are also many vegetables which contain acid in a disengaged state, without their possessing a red color. It is therefore evident, that the coloring particles have affinities for acids, alkalis, earths, and metallic oxides, which constitute a part of their chemical properties; and in consequence of which, their colors are more or less varied; therefore these particles form, with the stuff on which they are fixed, a compound which retains only some of their original properties; they are also modified by their union with alumine, or pure clay, metallic oxides, and some other substances; as are also those new compounds, when they are further combined with the stuff. OF MORDANTS. 18. The term mordant is derived from the French word mordre, which signifies to bite or corrode. In the art of dyeing, it is applied to designate all those substances employed for the purpose of facilitating or modifying the combination of the coloring particles with the stuff dyed. Dr. Bancroft, and Dr. Henry of Manchester, proposed to denominate these substances by the term basis, since the action of many of them does not depend on the acid or corroding principle; but this alteration has not been adopted. Mordants deserve the greatest attention; as by their means colors are varied, brightened, made to strike, and rendered more durable. We shall, therefore, examine the nature of the action of the principal bases or mordants, and endeavour to determine how their attractions serve to unite the coloring particles with the stuff, and how they affect the qualities of the colors. 19. A mordant is not always a simple agent, for new combinations are sometimes formed by the ingredients that compose it; so that the substances employed are not the immediate agents, but the compounds which they have formed. Sometimes the mordant is fixed with the coloring particles, and sometimes the stuff is impregnated with it; on other occasions, both these modes are united; and we may dye successively with liquors containing different substances, the last of which only can act on the particles with which the stuff is impregnated. The art of printing linen affords many processes, in which it is easy to observe the effects of mordants; to elucidate this subject, therefore, we shall mention a few examples. 20. The basis employed for linens intended to receive different shades of red, is prepared by dissolving in eight pounds of hot water, three pounds of alum, and one pound of acetate of lead, or sugar of lead, to which two ounces of potassa, and afterwards two ounces of powdered chalk are added. The alum is decomposed by the acetite of lead, because the oxide or calx of lead combines with the sulphuric or vitriolic acid, and forms an insoluble salt which is precipitated; the base of the alum, alumine, at the same time combines with the acetous acid, or vinegar, and produces an acetite of alumine; and the chalk and potassa answer the purpose of saturating the excess of acid. One of the advantages which result from the formation of the acetite of alumine is, that the alumine is retained in it by a much weaker affinity than in the alum; so that it more easily quits its menstruum, to combine with the stuff and coloring particles. Another advantage is, that the acid liquor, from which alumine is separated, has much less action on the color when it consists of the acetous, than when it consists of a stronger acid, such as the sulphuric. In short, the acetite of alumine not having the property of crystallising, the mordant, which is thickened with starch or gum, to prepare it for being applied to the block on which the design is engraved, does not curdle, as it would if it contained alum capable of crystallising. By attending to the operation performed upon a piece of linen cloth, we find, that when it has been impregnated by the mordant, in the manner determined by the design, it is put into a bath of madder; the whole of the cloth becomes colored, but the tinge is deeper in those parts which have received the mordant; there the coloring particles have combined with the alumine and the cotton, so that a triple compound has been formed, and the acetous acid separated from its basis remains in the bath. Thus the coloring particles, combined with the alumine and the stuff, are much more difficultly affected by external agents, than when they are in a separate state, or combined only with the stuff, without any intermediate bond of union; and on this property the operations, to which the cloth is afterwards subjected, are founded. After it has been maddered, it is boiled with bran, and spread upon the grass; and these operations are alternately repeated until the ground becomes white. The coloring particles, which have not united with the alumine, are altered in their composition, dissolved, and separated, while those that have combined with it remain, and are preserved, without alteration; and thus, the design alone remains colored. It seems that this decomposition of the coloring particles, by exposure on the grass and boiling with bran, is accomplished in the same manner as that of the coloring particles of flax, and admits of the same explanation. The only difference consists in substituting bran for alkalis, because they would dissolve a part of the coloring matter, which is fixed by the alumine, and would change its color; instead of which, the bran, having a much weaker action on this substance, affects only the coloring particles, which, by the action of the air, have been disposed more easily to solution. If, however, instead of the mordant, a solution of iron be employed, similar phenomena are exhibited. The coloring particles decompose the solution of iron, and form a triple compound with the stuff; but, instead of red, we obtain from the madder, brown colors of different shades, down even to black; and, by uniting these two mordants, alum and iron, we have mixed colors, inclining to red on the one hand, and to black on the other, such as mordoré, and puce color. Other colors are also procured by substituting dyers-weed for madder; and by means of these two coloring substances, indigo, and the two mordants above mentioned, we obtain most of the different shades that are observable in stuffs which are printed. 21. The different substances which enter into the composition of a mordant remain in combination till a new action is induced by the application of another substance. Thus the affinity of the stuff for one of their constituent parts proVOL. VII duces a decomposition and new combinations. But even this effect is sometimes incomplete, or does not at all take place without the action of another affinity, namely, that of the coloring particles. We have an example of this in the mixture of alum and tartar, which is one of the most common mordants in the dyeing of wool. 22. M. Berthollet, having dissolved equal weights of alum and tartar, found that the solubility of the tartar was increased by the mixture. By evaporation and a second crystallisation, the two salts were separated, so that no decomposition had taken place. Half an ounce of alum and one ounce of wool were then boiled together for an hour, and a precipitate was formed, which, being carefully washed, was found to consist of filaments of wool incrusted with earth. To this sulphuric acid was added, and the solution being evaporated to dryness, crystals of alum were produced, with the separation of some particles of carbonaceous matter. The liquid in which the wool had been boiled being evaporated, yielded only a few grains of alum; what remained would not crystallise. This being again dissolved, and precipitated by means of an alkali, the alumina which was thrown down was of a slate color, became black when placed on red-hot coals, and emitted alkaline vapors. From this experiment it appears that the alum was decomposed by the wool, and that part of the alumina had combined with its most detached filaments which were least retained by the force of aggregation; that part of its animal substance had been dissolved and precipitated by the alkali from the triple compound thus formed. 23. M. Berthollet made the same experiment with half an ounce of alum and two drams of tartar; no precipitation took place he obtained by evaporation a small portion of tartar, and some very irregular crystals of alum; the remainder would not crystallise: this, on being diluted with water, and precipitated by potassa, gave by evaporation a salt which burned like tartar. The wool which had been boiled with the alum felt harsh, but the other retained its softness. The first had acquired from the madder a more dull, though lighter tint, but the color of the latter was more full and bright. 24. From these experiments it appears, in the first place, that the wool had begun a decomposition of the alum; that it had united with a part of the alumine; and that even the part of the alum which retained its alumine had dissolved some of the animal matter. In the second place, that the tartar and alum, which cannot decompose each other solely by their own affinities, become capable of acting on each other when their affinities are assisted by that of the wool. And, in the third place, that the tartar appears principally useful for moderating the too powerful action of the alum upon the wool, whereby it is injured; for tartar is not used in the aluming of silk and thread, which have less action on the alum than wool has. As the decomposition of alum by the tartar and wool takes place in consequence of affinities' which nearly balance each other, and the process must therefore go on slowly, it is useful to keep the stuff impregnated with alum and tartar for some days in a moist 2 P |