the action of the trioxide itself upon moisture. Sulphur combines directly with carbon, at a red-heat, with the formation of a substance known as "carbon disulphide" (or "carbon bi- sulphide"), which has the chemical formula CS2. The vapor that is thus produced may be con- densed to a very volatile, mobile liquid, pos- sessing a high dispersive action upon light. Carbon disulphide freezes at about boils (under a pressure of one atmosphere) at 115° F., has a specific gravity of 1.29 and a specific heat of 0.247, and is used as a solvent for resins, sulphur, phosphorus, gutta percha and many other substances that do not dissolve in water. It is almost insoluble in water, but mixes readily with alcohol, ether and many kinds of oil. It is exceedingly inflammable, and its vapor forms explosive mixtures with air. The vapor of carbon disulphide takes fire, when heated in contact with air to 300° F., and this circumstance, taken in connection with the volatility of the substance and the explosive- ness of its vapor when mixed with air, renders the use of the disulphide exceedingly dangerous in the presence of any sort of a flame, or even in the presence of bodies heated as hot as 300° F. As ordinarily met with in commerce, car- The known compounds that contain sulphur in combination with two or more other ele- ments are almost innumerable, as are also the uses to which sulphur is put in the arts. Among the simpler compounds containing sulphur with two or more other elements, the various salts of sulphurous and sulphuric acids are exceedingly important. For data concerning sulphur black and the sulphur compounds that are in general use in the coal tar color industry, consult Cain and Thorpe, 'The Synthetic Dyestuffs and SULPHUR, Medical Uses of. Sulphur is prepared in various ways for use, both internally and externally, in medicine. It is used in the forms of washed, precipitated or milk of sul- phur, and sublimed sulphur, or flowers of sul- phur, corresponding to the manner of its prep- aration from crude sulphur-by washing, precipitation, or sublimation. The precipitated sulphur is regarded as the most efficacious, perhaps because of its finer division, which is chemical instead of mechanical. It is prepared by boiling equal parts of sulphur and freshly slacked lime for an hour, and then adding dilute hydrochloric acid until the alkalinity almost disappears. The sulphur precipitates as a white powder and is washed, and dried at a low temperature. Precipitated sulphur is much employed as a mild laxative, taken in medicinal fully interfere. Sulphur is also a valuable remedy in certain blood-diseases, chronic skin- diseases, chronic bronchitis, chronic rheu matism, etc., both internal administration - especially in the form of mineral waters con- taining sulphur- and sulphur baths being often efficacious. The administration of sulphur in obstinate chronic cases of many diseases often works such a change in the patient's condition as to give potency to other remedies given without effect. As a parasiticide, and especially in skin affections, ring-worm, itch, etc., sulphur ointment is a specific, or at least an active AND COMPRESSED GASES. SULPHUR DYESTUFFS. SULPHUR SPRINGS, Tex., city, county- seat of Hopkins County, on the Missouri, Kan- sas and Texas, and the Saint Louis South- western railroads, about 240 miles northeast of Austin, the capital, and 75 miles northeast of Dallas. It is in an agricultural and stock- raising region and has an extensive domestic export trade in cotton products, wheat, corn, fruit (peaches and plums), honey, poultry and livestock. It has two national banks with a combined capital of $200,000. The educational insitutions are the Central College (Methodist Episcopal, South), opened in 1876, and public a gaseous compound of hydrogen and sulphur, found abundantly in nature in gases issuing from crevices in volcanic regions, and oc- casionally in natural gas. It is one of the com- mon products of decomposition of vegetable substances, especially those of the leguminous family. It occurs in illuminating gas, from which it is scrupulously removed at consider- able expense. It is prepared on a large scale by heating together equal parts of vaseline or Sulphuretted hydrogen is a colorless, in- flammable gas, burning with a bluish flame, and The aqueous solution of sulphuretted hy- The gas may be liquefied at ordinary tem- Sulphuretted hydrogen is used in large quantities in the manufacture of sulphuric acid to remove the arsenic which is found in larger or smaller percentage in all acid made from pyrites. It is also used to precipitate copper from solutions containing salts of copper, and for precipitating gold and silver from sweepings and other waste material. In the chemist's laboratory it is one of the most valuable reagents. SULPHURIC ACID, or OIL OF VITRIOL, a common and exceedingly important oxy-acid of sulphur, having the chemical formula H.SO.. It was first prepared by Geber, in the 8th century, by distilling alum; and in the 15th century it was manufactured by burning sulphur with saltpetre, though the identity of the product so obtained with that described by Geber was not established until near the end of the 16th century. Considerable quantities of sulphuric acid were formerly manufactured by the distillation of ferrous sulphate, the practice of this method dating from the early part of the 18th century. At the present time practically all of the sulphuric acid that is used is prepared from sulphur dioxide gas, either by the "chamber process," or by the more recently perfected contact process," both of which are described in this article. When pure and free from water, sulphuric acid is a colorless liquid with an oily appearance, and a specific gravity of 1.89. It may be readily frozen, the solidified acid melting again at 50.9° F. It exhibits the phenomenon of surfusion to a marked extent, and the liquid acid can be cooled, much below the melting point here given, without inducing solidification; but if a crystal of the solid acid, or a small amount of sulphur trioxide, be added to the supercooled fluid, crystallization begins at once, and the temperature rises until it becomes 50.9° F., after which no further solidification occurs. The presence of a trace of water in the acid lowers the freezing point nearly to 32° F. If five parts (by weight) of sulphuric acid be mixed with nearly one part of water, and the solution is cooled by a freezing mixture, a definite hydrate of sulphuric acid, having the composition H2SO, + H2O, crystallizes out at 45° F. Another solid hydrate, having the composition H2SO4 + 4H2O, may also be prepared by cooling, to a much lower temperature, a mixture of sulphuric acid and water, containing 57.6 per cent of water. Several other hydrates are also believed to exist, and special study has been expended upon them, on account of their importance in the illustration of the "hydrate" theory of solutions. (Consult Mendeléeff, 'Principles of Chemistry, Vol. II). Sulphuric acid has no really definite boiling point. It begins to boil at about 550° F., the distillate containing sulphuric acid, water and sulphur trioxide. (See SULPHUR). The temperature of the liquid may be raised to 640° F., however, before a state corresponding in definiteness to the boiling point of water is attained, the vapor that passes off then consisting entirely of water vapor and free sulphur trioxide. At higher temperatures the decomposition is even more complete. Thus if a stream of the acid be allowed to flow over redhot bricks, it is broken up into sulphur dioxide (SO2), free oxygen and water-vapor. If the gases resulting from this decomposition are passed through cool water, and the steam that they contain is condensed and the sulphur dioxide removed by solution, a supply of pure oxygen gas is obtained. Pure anhydrous sulphuric acid has a specific heat, at ordinary temperatures, of about 0.34, and a coefficient of expansion (Fahrenheit scale) of about 0.000310. The concentrated acid is a powerfully corrosive poison, destroying organic tissues rapidly, and even charring paper and wood. It is also poisonous (though far less violently so) when administered in any considerable quantity in a highly dilute form. Concentrated sulphuric acid has a powerful affinity for water, its combination with water being attended by the evolution of a large amount of heat. The strong acid is used as a drying agent, for removing moisture from gases. For this purpose it is sometimes sufficient to allow the gas to stand for a time in a receiver containing a dish of the concentrated acid; but a more effective mode of procedure consists in passing the gas through tubes that are partially filled with fragments of pumice that have been wetted with the acid. Chemically, sulphuric acid is dibasic, either or both of its hydrogen atoms being replaceable by metals or other bases, the compounds that are thus formed being termed "sulphates." With the metals of the alkalis (which are monovalent), sulphuric acid therefore forms two kinds of sulphates, which may be sufficiently illustrated by the potassium salts. If one of the hydrogen atoms of the acid is replaced by potassium, the resulting salt, HKSO., is called "hydrogen potassium sulphate," or "acid potassium sulphate"; while if both are replaced, the resulting salt has the formula K2SO1, and is known as "normal potassium sulphate." Many of the sulphates of the metals occur native in large quantities, and many of them are of great value in the arts. Those that are of especial importance are described, in this encyclopedia, under the metals (or other bases) with which the acid is combined. The sulphate of barium is perhaps the most insoluble salt known. It is formed whenever a soluble barium salt (such as the chloride) is added to a solution of a soluble sulphate; and its formation constitutes a valuable test for sulphuric acid and the sulphates. See CHEMICAL ANALYSIS. When sulphur trioxide is dissolved in anhydrous sulphuric acid in the proportion of one molecule of the trioxide to one of the acid, a definite_compound having the formula H2SO, (or H2SO4.SO) is obtained. When pure, this substance is known as "pyrosulphuric acid." It is a dibasic acid, forming salts which are termed "pyrosulphates," but which are of comparatively little practical importance. Pyrosulphuric acid forms large crystals, which melt at 95° F., and it is easily decomposed by heat into ordinary sulphuric acid and free sulphur trioxide. Fuming sulphuric acid (now commonly known in the arts as "oleum" but formerely called "Nordhausen oil of vitriol") consists of a mixture of pyrosulphuric acid and ordinary sulphuric acid and may be regarded as a solution of sulphur trioxide in sulphuric acid, the trioxide not being present in sufficient quantity to convert the ordinary acid entirely into pyrosulphuric acid. It fumes strongly in the air, gives off sulphur trioxide when heated and is prepared by the "contact process," described in this article. The uses of sulphuric acid in chemistry and in the arts are past enumeration; for this acid is one of the most important chemical substances known, and it is employed is so many industrial processes that it has been said that the wealth and prosperity of a nation can be estimated from its consumption of sulphuric acid. About half of the total quantity manufactured in the United States is consumed in the preparation of fertilizers. The two general methods now in use for manufacturing the acid are described in this article. The sulphur used for the manufacture of sulphuric acid is obtained (1) from the gases generated by burning iron pyrites (FeS2), (2) from the sulphur deposits of Louisiana, Sicily and elsewhere, and (3) to a very limited extent from the waste gases given off by sulphide smelters. At the present time pyrites is the most important source, but it is probable that smelter gases will be utilized to a greatly increased extent in the future, and they may eventually compete with pyrites. The sulphur dioxide that is now wasted by discharging the fumes from smelters into the air would far more than supply the United States with sulphuric acid. Moreover, the fumes are exceedingly objectionable, and they are destructive to vegetation. The fundamental principles in the manufacture of sulphuric acid are (1) to oxidize sulphur or a suitable sulphide, so as to obtain sulphur dioxide, SO2; (2) to further oxidize this to the trioxide, SO; and (3) to effect the combination of the trioxide with water, in ac-. cordance with the equation SO+H2O= H2SO1. In attempting to carry out the second of these processes, however, we are confronted by the fact that sulphur dioxide does not readily take up oxygen, so as to become completely converted into the trioxide. To effect this oxidation we are in fact compelled to resort to one or the other of two expedients: (1) To mix a certain amount of an oxide of nitrogen with the sulphur dioxide and air-the oxide of nitrogen then acting as a sort of "carrier", taking up oxygen from the air and passing it on to the sulphur dioxide; or (2) to subject a mixture of air and sulphur dioxide to the action of a suitable catalyzer. The first of these expedients is used in the "chamber process" and the second in the "contact process." The first step in the manufacture of sulphuric acid is to provide a suitable supply of sulphur dioxide gas. This is usually obtained by burning sulphur or iron pyrites in a special furnace and considerable skill and judgment are required in this part of the operation, to obtain gases of proper composition. It is also important to minimize the quantity of dust that the gases carry over into the later parts of the process. Settling chambers, baffle plates, centrifugal separators, parallel-plate separators, and filtration through piles of marbles or other loosely aggregated solid lumps are among the devices used for the removal of the dust. Chamber Process.-In manufacturing sulphuric acid by the so-called "chamber process" the hot gases from the burners (consisting of air, sulphur dioxide and moisture) pass first over "niter pots," which contain nitrate of soda and sulphuric acid, and which give off the nitric oxide gas that is to act as an oxygen carrier. Then, after passing through the dustremoving apparatus, the gases are passed upward through a tower (technically known as a "Glover tower") that is loosely filled with fragments of coke, pumice, acid-proof stoneware or other inert material to distribute the flow, and here they are met by a downward stream of aqueous sulphuric acid obtained from a later stage of the process and containing oxides of nitrogen in solution. The precise reactions that occur cannot be discussed here, partly because they are complicated, and partly because they are not fully understood. The general effect, however, is to oxidize the SO2 to SO, and the downward-flowing stream of weak acid dissolves the SO, and thereby becomes stronger. In certain plants of recent design the oxidation of the sulphur dioxide and the absorption of the resulting trioxide are carried out in a series of Glover towers, without the use of chambers of any sort; but it is usual, after the gases have passed through one or two Glover towers, to cause them to enter large lead-lined chambers (from which the process takes its name), where the oxidation of the dioxide and the consequent strengthening of the acid are continued. Liquid sulphuric acid settles in the bottom of these chambers, and is drawn off from time to time. Steam or water is sprayed into certain of the chambers, as needed, to provide the H2O that is required for the formation of the H2SO4. The gases coming from the last chamber are passed up through a "Gay-Lussac tower," which resembles the Glover tower in general construction. liquid that is sent down through this tower, however, is concentrated sulphuric acid, and its purpose is to absorb the nitric oxide gas that is present, thereby preventing its loss and diminishing the quantity of nitre that must be used in the early part of the process. Upon leaving this tower the gases (which then consist mainly of nitrogen and oxygen) enter a stack and pass off into the atmosphere. The acid that is drawn off from the bottom of the final GayLussac tower contains oxides of nitrogen in solution, and is introduced (diluted, as may be necessary, with weaker acid) into the tops of the Glover towers. As the acid passes down through a Glover tower, however, the heat due to the reactions that occur, added to that which the entering gases already possess, drives off the nitrous oxides, and these keep returning upward through the tower with the sulphur oxides and air, while acid nearly free from nitrous oxides comes away from the bottom of the tower. The Sulphuric acid, as made by the chamber process (and especially when made from pyrites) is likely to be contaminated with lead, arsenic, nitrous oxides and many other substances. Certain of these may be removed in considerable measure by treatment with sulphuretted hydrogen. If an acid of high purity is required, however, it is better to make it by the contact process, presently to be described. When treated with sulphuretted hydrogen for the removal of impurities, the acid should not have a greater specific gravity than 1.4, corresponding to about 50 per cent of actual H2SO and must be diluted to this strength if it is already stronger. After the removal of the arsenic the purified acid is concentrated by evaporation if a strong product is required. The evaporation may be carried out in leaden pans, but a better product is obtained by effecting the concentration in platinum stills. Owing to the high cost of platinum, however, it is common to perform the evaporation in a series of evaporating dishes constructed of fused silica. These are arranged like a flight of steps, the lip of each one projecting out over the next dish below. A slow stream of acid is kept running down through the cascades of dishes, while heat is applied to each dish from below. When an apparatus of this kind is properly arranged and operated it gives excellent results. Hoods should be arranged over the dishes, however, to take up the vapors that are given off and dispose of them in some proper way. The Contact Process.- In the contact process for the manufacture of sulphuric acid, the sulphur dioxide is caused to combine with the oxygen of the air by bringing the mixed gases into contact with finely divided platinum, or with platinized asbestos. The catalytic action of platinum (that is, its power of inducing combination in this way, without being itself consumed or otherwise permanently affected) was discovered by Sir Humphrey Davy, in 1818; and in 1824 Doebereiner showed that finely divided platinum can effect the ignition of a jet of hydrogen, when this gas impinges upon it in contact with air. Peregrine Phillips, of Bristol, England, first produced sulphur trioxide by utilizing the catalytic effect of finely divided platinum upon a mixture of oxygen and sulphur dioxide, taking out a patent for this process in 1831; and Schneider, in 1848, made a working model of an apparatus for manufacturing sulphuric acid by this method. Since that time many attempts have been made to make the contact process practicable for the manufacture of sulphuric acid, and many other catalytic agents have been tried besides platinum. It was not until about 1898, however, that the various practical difficulties involved in the process were satisfactorily overcome, largely through the labors of Herr Knietsch of the Badische Anilin und Soda-Fabrik, a German company for the manufacture of chemical substances of nearly every kind. It was found that the prime condition of success in the application of the contact method is that the gases that are treated shall be absolutely free from dust, arsenic, mercury and certain other substances. The gases from the pyrites-roaster are cooled very slowly and are then purified by filtration and washing. When passed to the tubes containing the platinized asbestos that is used as the catalytic agent, 100 volumes of the roastergas contain 7 volumes of sulphur dioxide, 10 volumes of oxygen and 83 volumes of nitrogen (from the air). The catalytic platinum is maintained at a temperature of about 750° F., since it is found that at this temperature the production of sulphur trioxide is about 98 per cent of the theoretical production. The nitrogen that is present has no influence upon the reaction, when the apparatus is working properly. The sulphur trioxide that is produced by this method needs only to be dissolved in previously prepared sulphuric acid containing more or less water, in order to yield an acid that is quite pure. It might naturally be supposed that water would be the best absorbent for the trioxide; but it is found that an acid that contains from 97 to 99 per cent of H2SO4 is a better absorbent; and in the practical conduct of the process the trioxide is absorbed by an acid of this strength; the stronger acid that its solution yields being continuously drawn off and continuously replaced by fresh supplies of the 97 to 99 per cent acid, except when fuming acid of a very high degree of concentration is wanted. The minute details of the contact process are trade secrets and are carefully guarded. The standard work on sulphuric acid manufacture is Lunge's 'Sulphuric Acid and Alkali. Very good general accounts will be found, however, in Rogers' 'Manual of Industrial Chemistry' and Thorp's 'Outlines of Industrial Chemistry.' ALLAN D. RISTEEN. SULPHURIC ETHER. See ETHER. SULPHUROUS ACID, an acid having (probably) the formula H.SO., and prepared by dissolving sulphur dioxide gas (see SULPHUR) in water to saturation; the acid being formed by the union of one molecule of the dioxide with one molcule of water, according to the equation SO2+ H2OH2SO3. Sulphurous acid has never been isolated, and is known only in its aqueous solution, in combination with bases in the form of the salts known as "sulphites," and as a solid hydrate. At 70° F. water dissolves about 35 times its own volumé of sulphur dioxide; the solubility being greater at lower temperatures, and less at higher ones. When an aqueous solution of sulphurous acid is cooled below 41° F., a crystalline hydrate of the acid separates out, the composition of which is not definitely known. Sulphurous acid has the taste and smell of sulphur dioxide gas, and is strongly acid. It readily gives off sulphur dioxide gas, and upon standing in contact with the air it gradually absorbs oxygen and becomes converted into sulphuric acid. Its composition is also modified by the action of light, probably by the formation of a more complex oxy-acid of sulphur. It acts as a dibasic acid, combining with the oxides, hydrates and carbonates of many of the metals to form salts (that is, sulphites) which are readily decomposed by the addition of stronger acids, with the liberation of sulphur dioxide. It is used in the bleaching of silk and wool but not so much as formerly, having been largely displaced by hydrogen peroxide. When the hydrogen atoms of the acid are both replaced by a metallic base, the resulting salt is called a "normal sulphite"; and when only half of the hydrogen of the acid is so replaced, the salt is called an "acid sulphite," or a "bisulphite." Both of the sulphites of sodium are extensively used in photography; the normal sulphite having the formula Na2SO37H2O, and the acid sulphite the formula HNaSO3. PHOTOGRAPHY). Industrially, the bisulphites of calcium and of magnesium are of exceeding importance, since the aqueous solutions of these substances possess the power of dissolving the gummy matters by which the fibres of certain kinds of wood are cemented together. Upon this property, the "sulphite process" for the (See SULPICIUS SEVERUS, sul-pish'ĭ-us sěvērus, Roman ecclesiastical writer: b. Aquitania, 363 A.D.; d. Marseilles, between 410 and 429. He was from a family of high rank and in the practice of the law at Toulouse attained a great reputation for learning and eloquence and led a gay though charitable life. The death of his wife led him to more serious pursuits. Having entered a monastery, he spent some years in preparing an abridgment of the scriptural narrative, which from the purity of its style was long a favorite textbook in the schools of the Middle Ages, but is liable to the charge of serious tampering with the facts, arising in part probably from the desire to rebuke in this guise some contemporary rulers. He continued this history, describing the destruction of Jerusalem and bringing the narrative down to his own time, under the title of 'The Chronicle of Sulpicius Severus,' in which he varies materially from Josephus. His other works are 'Life of Saint Martin, Bishop of Tours'; 'Three Dialogues' and a collection of letters. From the elegance of his Latinity he was called, not undeservedly, "the Christian Sallust." His works have been often printed. SULTAN, in Arabic, signifies monarch, ruler. The title is borne by various Mohammedan rulers, while the Turkish emperor assumes the title of Sultan-es-selatin, Sultan of sultans. The daughters of the sultan have also the title of sultan. The title of sultana is given out of Turkey to the chief concubines of the sultan, but no such title is in use for them in Turkey. If the mother of the sultan is living she is styled sultan Valide SULU, soo-loo', or JOLO, hō-lō', Philippines. (1) An archipelago, consisting of over 400 islands, forming the southern central portion of the Philippine Archipelago, lying between the parallels 4° 30′ and 121° 52′ N. lat. and the meridians 119° 25′ and 121° 52′ E. long.; area 1,029 square miles. The archipelago is surrounded by the Sulu and Mindanao seas on the north and west and the Celebes Sea on the south and east. The islands form a long chain extending from northeast to southwest and are divided into five principal groups: (1) Balanguingui; (2) Pañgutárang; (3) Sulu; (4) Tapul; (5) Tawi Tawi. The larger islands are generally high and of volcanic formation; the smaller islands are low and rest on coral; mountain chains traverse the islands of Sulu and Tawi Tawi. The larger islands are fertile; rice, coffee, chocolate, corn, hemp, saffron, indigo, sesame and cotton are cultivated, but not as a rule for export. The raising of horses, cattle and goats is an important industry; there is some metal working in the manufacture of chisels, knives, etc., and weaving for home consumption. The chief industry from the commercial standpoint is pearl and pearl shell fishing, large quantities of pearl shell especially being exported; other exports are shark's fins, beche de mer and native cordage. The trade is largely in the hands of the Chinese. The forests contain many of the most valuable woods of the East. The people of (a) the archipelago are divided into four groups, according to their origin and customs: The Guimbajanos, the aborigines living in the mountains; (b) the Malay and Visayan slaves; (c) the Samales; (d) the Moros proper, the dominating race. Mohammedanism is the prevailing religion; polygamy and slavery are recognized institutions. Piracy was formerly a regular occupation of the people and their depredations were carried as far as Singapore. (See MOROS). Spain never occupied but a few towns on the coast and the native government remained largely independent of Spanish dominion. When the islands were transferred to the United States, after the Spanish-American War, negotiations were immediately begun for establishing satisfactory relations between the United States government and the sultan of Sulu and his datos (or chiefs). In August 1899 a treaty was signed in accordance with which the sovereignty of the United States over the whole archipelago was recognized, but the government of the sultan and datos continued under this supreme jurisdiction, the rights and religion of the Moros to be respected, with the following important stipulations: the United States shall occupy and control such parts of the archipelago as public interest demands; any person can purchase land with the sultan's consent; piracy shall be suppressed; American courts shall have jurisdiction except between Moros; the American government shall protect the island against foreign aggression. Pop. (estimated) 22,680. (2) A group of islands in the central part of the Sulu Archipelago, lying between the Balanguingui group on the north and the Tapul group on the south; area 380 square miles. All of the larger islands of this group are volcanic, each of them being formed of a central peak sloping to a narrow stretch of level coast land; the islets are generally rocks. All the staples of the archipelago are cultivated; a small amount of hemp and indigo is exported; but cattle raising and fishing occupy a larger number of the inhabitants. trade between islands is by native craft; the port of export is the town of Sulu. Pop. 14,500. (3) An island, the central and largest one of the Sulu group; area 333 square miles. It is traversed from northeast to southwest by three nearly parallel mountain chains, between which lie fertile valleys; there are several important peaks, of which the highest has an elevation of 2,894 feet. There are numerous small streams; which are nearly or completely dry during the summer season. The climate is particularly good, the temperature being even and unusually cool for the latitude. The soil is fertile and is well cultivated; rice, however, is imported and the chief articles of export, as in the rest of the Sulu Archipelago, are the products of the fisheries. The mountains are heavily wooded and valuable cabinet woods are also among the exports. Under the American jurisdiction, a school has been established on the island. (4) A town, capital of the Sulu Archipelago, situated on the northwest coast of Sulu Island, 540 miles south of Manila. was the ancient residence of the Sulu sultans, but scarcely a trace of the ancient Moro town remains; the present town was built in 1878 bv the Spaniards. It is surrounded by a wall, within which the town is regularly laid out, with three principal streets, broad and well The It |