1850, for medical aid, he was seized with the illness that terminated his life. He published at various times several sermons and addresses, the "Life of Brainerd" (1822), a volume on the "Atonement" (1826), the "Life of Edwards" (1830), and the "Hebrew Wife" (1836). A volume of his "Select Discourses" was published in 1851, together with an interesting memoir by his brother, the Rev. Dr. W. T. Dwight. DWINA, or DVINA, NORTHERN, a river of Russia in Europe, formed in the government of Vologda by the junction of the Sookhona and Vitchegda, flows N. N. W. into the government of Archangel, where it receives several tributaries, and after a course of more than 400 miles falls through several mouths, forming a number of islands, into the White sea, about 40 miles below the city of Archangel. It is navigable for its whole length, and is the largest stream in northern Europe, traversing as it does a marshy_country, and increased by numerous affluents. It forms a part of a system of canals completed in 1807, by which a water communication is established between the White, Baltic, Black, and Caspian seas. (For SOUTHERN DWINA, see Düna.)

DYAKS. See BORNEO.

DYCE, ALEXANDER, a Scottish author, born in Edinburgh, June 30, 1797. He completed his education at Exeter college, Oxford, subsequently took orders, and in 1827 settled in London, where he has since lived. He has edited, with notes and biographies, editions of the works of Peele, Greene, Webster, Middleton, Beaumont and Fletcher, Marlow, and Shirley. In 1856 he edited "Recollections of the Table Talk of Samuel Rogers ;" and in 1858 he completed an edition of Shakespeare in 6 vols., the text of which has been highly commended. He has also contributed biographies for Pickering's "Aldine Poets." Among his miscellaneous publications are: "Select Translations from Quintus Smyrnæus;" editions of Collins's and Skelton's poems; Specimens of British Poetesses;" Kemp's "Nine Days' Wonder," and some old plays. To Shakespearean literature he has contributed "Remarks on Collier's and Knight's Editions of Shakespeare," and "A few Notes on Shakespeare"-a review of the recent emendations proposed by Mr. Collier.-WILLIAM, a British artist, born in Scotland at the beginning of this century. He studied painting at the academy of Edinburgh, but attracted little notice until the production of his fresco studies in the exhibition at Westminster hall in 1844. The admirable manner in which these were executed procured him commissions to make designs for the new houses of parliament. His "Baptism of Ethelbert," on one of the mural compartments of the new house of lords, is regarded as one of his best works. He was made a royal academician in 1848. Among his pictures exhibited in London in 1851 was "Lear in the Storm," and in Paris in 1855, "Meeting of Jacob and Rachel," and "King Joash shooting the Arrow of Deliverance."

DYEING. Among the earliest records of the human race we find frequent intimations of an appreciation of the brilliant hues such as are displayed by nature in the plumage of birds, in flowers, crystals, and shells, and in the morning and evening sky; and the instinct implanted in man of imitating the works of his Creator is seen in the desire to appropriate these rich colors to the adornment of his own apparel. The gift of the coat of many colors was early regarded as the highest mark of affection. To the fine linen (which was probably the same as our cotton) were transferred the brilliant blue, scarlet, and purple hues extracted from vegetable or animal substances, the last named color reserved exclusively for the vestments of kings and high priests. The skins of the ram and the badger made use of for the tabernacle were dyed red, and in the time of Moses the art of coloring woollen purple was already known. The Tyrians early attained a high perfection in the art, and their king sent to Solomon a man skilful to work "in purple and blue, and in fine linen and in crimson." Along the coast of Phoenicia they found the two kinds of shellfish called by Pliny the buccinum and purpura, and from each animal they extracted a single drop of the precious juice which caused their name to be ever associated with the rich purple dye. In such estimation was this held in the time of the Roman emperors, that a pound weight of the cloth which had been twice dipped in it was sold, as Pliny states, for a sum worth about $150. But its use being restricted to the emperors, the art of preparing it was at last lost. It was revived in the 17th and 18th centuries in England and France, but better colors and cheaper processes were then in use. The discoverers and early conquerors of the countries of North and South America were astonished by the skill exhibited by the ancient Peruvians and Mexicans in the application of the numerous beautiful dyes they extracted from the woods of their forests. According to Pliny, the methods of dyeing black, blue, yellow, and green were brought into Greece on the return of the expedition of Alexander the Great from India, where it appears that the art of coloring cotton cloths with rich and permanent dyes had long been known and practised. The Venetians and Genoese in the height of their prosperity, in the time of the crusades, transferred the art to Italy; and Florence in the early part of the 14th century, it is said, contained not less than 200 dyeing establishments. The important dye stuff archil was discovered about the year 1300 by a merchant of Florence. In 1429 a work upon dyeing was published in Venice, of which subsequent editions were issued as late as the year 1548, containing full details of the processes employed. From this work it would appear that the use of indigo was unknown in Europe up to 1548, though in India it was probably an important article in dyeing at the remotest periods. It was afterward introduced from America together with cochineal,

logwood, annotto, quercitron, Brazil wood, &c. But its use in England and Saxony, as of logwood also, met with the most determined opposition. The cultivators of the woad then in use for dyeing blue caused decrees to be issued against indigo as a most dangerous product. By the German diet in 1577 it was declared to be "a pernicious, deceitful, eating, and corrosive dye;" and the name was given it of food for the devil. An act of parliament in the reign of Elizabeth forbade its use, and authorized the destruction of it and of logwood wherever found, and this continued in force for nearly a century. About the year 1630 it was discovered that the crimson color obtained from cochineal might be converted into a brilliant scarlet by the application of a salt of tin. The introduction of this metal as an occasional substitute for alum as a mordant is attributed to a dyer named Cornelius Drebbel. The use of pure mordants marks the great improvement of the art in modern times, as also the introduction of a great variety of new dyes obtained from mineral substances. The Flemings during the 17th century carried the skill to which they had attained in this art into Germany, France, and England. The French about the same time directed particular attention to it, and men of eminence in chemical science, as Du Fay, Hellot, Macquer, and Berthollet, were appointed by the government to investigate and perfect the processes. The method practised in the East of giving to cotton the beautiful and permanent Turkey red dye was made known in their publications, and the art was about the same time introduced into France by some Greek dyers. The business was afterward permanently established at Glasgow by a Frenchman named Papillon. The branch of dyeing called calico printing, by which different colors are produced on the same piece of cloth by dipping it into a dye of one color, was known at a very early period, and the process is lucidly described in a few words by Pliny, as it was practised in Egypt in the first century. (See CALICO.)-The object to be attained by dyeing is the fixing of certain colors permanently and so as to present a uniform shade in the fibres of textile materials and other substances. The subjects operated upon are various in their characters, some being of animal origin, as silks and woollens, and others being composed of vegetable matters alone, as cottons, linens, &c. These two classes differ in the facility with which they imbibe the coloring matters, the animal tissue taking much more brilliant shades than the vegetable. The colors may be applied to each of these in the raw fibre, in the spun yarn, or in the woven fabric. Hence it is apparent that there must be much diversity in the processes. But when it is further considered that the coloring matters are themselves of the most diverse composition, drawn from the vegetable, animal, and mineral kingdoms, and that different substances are brought together to produce by their reactions effects dependent on

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the intricate danges which take place among the elements of organic bodies, the art is readily understood to be exceedingly complicated in its nature, and to some extent so empirical in its processes, that its exposition must involve a vast amount of details. In an article like the present only a general idea of the principles of the art and of the materials employed can be given. The colors obtained from vegetable matters are most numerous; they are extracted generally by watery infusion, though some require for their solution ether, alcohol, or the fixed oils. The most common colors are yellow, brown, and red; the only blue vegetable dyes are litmus and indigo; nut galls, sumach, and the cashew nut afford a black dye; and by the mixing of these, or their treatment with other substances, numerous shades or even different colors are obtained. The animal kingdom affords the beautiful scarlet and crimson dyes, which are extracted from the bodies of the cochineal and kermes insects. Hoofs and horns and other refuse animal matters yield the cyanogen which enters into the composition of Prussian blue. From the mineral kingdom is derived a great variety of brilliant colors, produced from the salts of the different metals. The same metal in its various combinations gives many colors, as is seen in the crystals of its natural salts. Thus iron in the form of a sulphate furnishes the ancient nankeen or iron buff, as a nitrate it affords various shades of blue, and in other combinations it is made to yield a black, slate color, &c. The chrome and lead salts are particularly interesting for the variety and brilliancy of their colors. The former are remarkable for their permanency also, and the extent of their possible applications is by no means yet fully appreciated. The mordants also, which are used to prepare the fibre for the reception and fixing of the dye, come almost wholly from the mineral kingdom. They are soluble combinations of alumina, of protoxide of lead, of oxide of iron, or of oxide of tin or of copper, with some acid, commonly acetic acid. Materials to be dyed seldom have such an affinity for the coloring matters that they will receive these without previous preparation. Some few colors, however, which are technically called substantive, are applied directly to the stuffs, and become fixed without the intervention of any other matter. But mordants are commonly required. They have the property of fixing themselves to the fibre, and of uniting chemically with the dye afterward applied, thus binding them fast together. The name is given them from the old opinion that their action was mechanical, and that they bit into (Lat. mordeo) and opened the pores of the fibre for the reception of the coloring matters. Some of them serve, at the same time that they fix the color, to modify its shade, and give to it its highest tone. For these the name alterants has been proposed by Berthollet, to distinguish them from the simple mordants. Oxide of iron often has this effect of changing the ordinary colors of a dye. Thus a

decoction of madder applied to unmordanted cotton gives a fugitive and dirty red color. If the cotton be first passed through a weak solution of acetate of alumina, and then dried at a high temperature, afterward washed, next treated with a hot decoction of madder, and again washed, it will be found to have received a fine red, which is fixed, so as to resist the action of air, light, and water. But if, instead of alumina, oxide of iron is employed as the mordant, a purple color will be obtained. So in dyeing with cochineal, the aluminous mordant produces a crimson color; but if oxide of iron is used instead, the result is black. By mixing mordants different shades and colors are produced, and varying the strength of the solutions, and other similar expedients, afford opportunities for the exercise of much ingenuity in obtaining a variety of effects. A thorough familiarity with the chemical action of the salts employed upon each other is essential to skilfully conduct these complicated processes, and obtain most directly and with the greatest economy the effects desired. It is often the case that the color is produced in the cloth in the form of a precipitate by the interchange of the elements of 2 different chemical compounds taking place in the fibre of the stuff, on this being dipped first into the solution of one, and then into that of the other. The new color obtained by this chemical reaction is at the same time fixed in the fibre, as though one of the substances acted as a mordant; this may be the case when neither solution would afford any color whatever to the material to be dyed. Thus an aqueous solution of nitrate or acetate of lead or of bichromate of potash imparts no color to cloth; if applied to it, either may be washed out; but one being applied to the same stuff after it has received the other, an insoluble precipitate of chrome yellow (chromate of lead) is obtained, which attaches itself to the stuff as a fast dye. The oxygen of the air is also made to act upon colors subject to its influence, bringing them out as the material exposed to it is converted into an oxide. Solutions of salts which evolve oxygen are used to produce the same effect. Acids, too, are added to alkaline solutions to neutralize them and cause the dye they hold in solution to be liberated as they precipitate among the fibres of the cloth. In the process called mandarining an acid is made to act directly upon the fibre of the cloth, which in this case must be of animal substance, as silk or woollen. An orange dye is thus produced by the action of dilute nitric acid. An interesting account is given by Tomlinson, in the "Useful Arts and Manufactures of Great Britain," of the operations conducted in one of the great English cotton dye houses, near Bolton. In an immense apartment, the basement story of a large cotton mill, is collected the great variety of apparatus employed: cisterns of stone for bleaching and washing; dashwheels, &c., also for washing; "dye becks" and "soap becks," or vessels containing the dyestuffs and the soap and water; mangles for roll

ing cloth, others with brushes for laying the fibre, squeezing rollers, and drying machines. Boilers are seen in operation heated by steam conveyed through them in pipes; water flows in every direction, the waste running out in streams of all colors, and the fresh conveyed about by numerous pipes. The water must be of the purest quality, uncontaminated by any foreign substances, whose presence would injuriously affect the delicate chemical processes. The dyestuffs are ground and mixed in another room, where they are also stored. The infusions are made in tubs or vats, some in cold water, and some by boiling. The dyestuffs are introduced in the form of a coarse powder, or they may be enclosed in bags through which the color is imparted to the liquid. The cotton cloth is first prepared by thorough cleansing in order to remove all extraneous matters that may be attached to the fibre; acid waters are sometimes used for this purpose, dissolving out the calcareous earth and oxide of iron which are frequently present. The mordant is then applied by soaking the cloth in solutions of alum, each pound of cotton requiring 4 oz. of alum; or if a black color is to be produced, the mordant is a preparation of nut galls boiled for 2 hours in water. The preparatory operations are expedited by passing the cloth in lengths of 100 yards or more over and under different rollers, one of which is set under the liquid in the vat. The fluid is thus kept uniformly mixed, and the cloth is equally saturated with it. As it comes out of the vat it is made to pass between 2 rollers, which press out the superfluous moisture, and it is then ready for another dipping. After the dyeing has been completed, the cloth must be submitted to the finishing processes. The loose portions of the coloring matters are removed by washing, and the colors are brightened and rendered more permanent by passing the cloth through solutions of cow dung in water, or of the artificial preparations of phosphates used as a substitute and called by this name, or a solution of bran is used to effect a similar purpose. These are processes adopted in calico printing particularly, as is that of fixing the colors by steaming the cloth. Chloride of lime in solution is also employed to remove the excess of coloring matters. By next passing the cloth through squeezing rollers the water is pressed out, and in the drying machine it is in a few minutes rendered nearly dry, the centrifugal force produced by the rapid revolution of a cylinder expelling the moisture, which escapes through apertures made for the purpose. The starching and subsequent drying by steam follow, and the cloth is ready for the final process of calendering.-In 1850 a patent was granted in England to Mr. Jean Adolphe Carton for improvements in dyeing, which consist in the preparation of 4 mordants to be used instead of the cream of tartar, and cream of tartar and alum, now commonly employed, whereby colors will be produced at a cheaper rate and of superior brilliancy and variety. The first mordant is prepared by