co. of sulphur, is a yellow gritty powder having a It occurs in some schistose rocks, and in coal and lignite deposits, and is deposited from the sulphuretted waters of certain mineral springs. It is found in Sicily in beds of blue clay lying in a matrix of rock salt, gypsum, and celestine. (See STRONTIUM.) It also exists in primitive rocks, as granite and mica, and abounds in the lava fissures of volcanic craters, as in the solfatara near Naples and at Popocatepetl, MexiIt is a constituent of many minerals, such as iron and copper pyrites, galena or sulphuret of lead, cinnabar or sulphuret of mercury, gray antimony, and realgar or sulphuret of arsenic; also of ternary salts of metals, such as the sulphates of copper and iron, and of strontia, barium, and calcium (celestine, heavy spar, and gypsum); and of more soluble compounds which are constituents of mineral waters, as the sulphates of magnesium and sodium (Epsom and Glauber's salts). It is a constituent of the proteine compounds of animals and vegetables, in the taurine of bile and the cystine of urine, and certain volatile oils, as oil of onions and oil of mustard.—Sulphur is obtained from the natural deposits of free sulphur by melting or by distillation. Rich deposits are simply melted in large cast-iron or earthen caldrons, the gangue and small stones being removed with perforated ladles. Sometimes rude furnaces somewhat like lime kilns are employed for the coarser deposits, in which a portion of the sulphur is burned, while the great mass is drawn off at the bottom. A better method than the latter is that of distillation, as the product is much purer. This is done in large earthen pots or retorts placed in a long furnace. Rude receivers of earthenware or wood are placed outside of the fur-separated from sulphides of electro-positive nace in which the sublimate is condensed. metals. The second variety he named electroThe product obtained by melting is known as negative sulphur, because it appears at the rough sulphur, and contains about 3 per cent. negative pole of the battery during the decomof foreign matter, from which it is separated position of sulphurous acid, and separates from by distillation, in stills having large chambers sulphur compounds with electro-negative elefor condensers, in which it is deposited in the ments, as chlorine, bromine, iodine, and oxyform known as flowers of sulphur; or it may gen. Soluble sulphur, or that which is soluble be condensed in the liquid form in smaller and in bisulphide of carbon, presents three forms, hotter receivers, and cast into cylinders called two crystalline and one amorphous. In the roll sulphur. Sulphur may also be obtained first the crystals are octahedrons with a rhomfrom iron pyrites by heating it in close ves- bic base, and all the modifications of both varisels, in which case the dioxide parts with one eties have a tendency finally to assume this molecule of sulphur and becomes protoxide. It form. It is formed when sulphur separates is one of the products of the heating of copper from its solutions at common temperatures. pyrites preliminary to copper smelting. Sul- The second crystalline form is that of brownphur is also a by-product of gas manufacture ish yellow needles belonging to the oblique when salts of iron are used to decompose sul-prismatic system. It is obtained by melting a phuretted hydrogen. (See Gas, vol. vii., p. mass of sulphur, allowing it to solidify on the 637.) The iron salt, which before using is surface, piercing the crust, and allowing the mixed with lime and exposed to the air to con- fluid portion to run out. On breaking away a vert it into peroxide, in the gas-purifying pro- part of the crust the long, needle-like crystals cess becomes a hydrated sulphide. This is again will be exposed to view. These two forms reconverted into peroxide by exposure to the air, are not only very unlike as to their crystalwith evolution of sulphur.-Properties. Native lography, but differ widely in their specific sulphur occurs either in amorphous masses, gravities and in their melting points, the octaor in transparent yellow crystals derived from hedral crystals having a density of 2:05 and the octahedron with a rhombic base. Sub-melting at 239° F., while the needles have a limed sulphur of commerce, known as flowers density of only 1.98, that of ordinary roll sul phur, and melt at 248°. After a time the prismatic crystals will be found to consist of aggregations of minute octahedral crystals. When a saturated solution of sulphur in hot turpentine cools, the first crystals formed will be prismatic, while those which are deposited when the solution is comparatively cool will be octahedrons. Roll sulphur or brimstone is at first prismatic, but after keeping becomes octahedral, and the change of form is attended with the evolution of heat. The amorphous variety of soluble sulphur is precipitated as a greenish white emulsion on adding acids to dilute solutions of alkaline polysulphides. This amorphous sulphur changes after a time into a mass of octahedral crystals. Ordinary sublimed sulphur (flowers of sulphur) belongs to this variety, but always contains small quantities of one of the insoluble modifications. The principal modifications of the insoluble variety of sulphur are: 1, an amorphous modification, obtained as a soft pasty mass, or magma, by decomposing bisulphide of chlorine with water, or by adding dilute hydrochloric acid to a solution of a hyposulphite; 2, a plastic form, obtained by pouring viscid sulphur raised to nearly 500° into cold water. The effect of heat upon sulphur is remarkable. It begins to melt at about 239°, and between 248° and 284° it is yellow, transparent, and limpid. As the temperature rises to 356° it becomes brown, and at last nearly black and opaque and quite viscid. At this point the temperature becomes stationary for a time, although the supply of heat is kept up, in consequence of a molecular change which is going on. Soon the temperature again rises, and when it has reached about 500° the mass becomes more liquid, but retains considerable viscosity. If it is now suddenly cooled by pouring it in a small stream into cold water, a brown tenacious mass is produced, which may be drawn out into elastic threads having a specific gravity of only 1.957. In a few hours it becomes yellow and opaque, and passes into the octahedral form. If the ductile sulphur is heated to 212°, the change is sudden, with a further rise of heat, from condensation, to 230°.- Compounds. Sulphur forms with oxygen an interesting series of compounds: two anhydrous oxides, or anhydrides, sulphurous anhydride, SO,, and sulphuric anhydride, SO,; two acids, sulphurous and sulphuric, formed by the union of these anhydrides respectively with water, and a further series of acids which have no corresponding anhydrides. The constitution of all these bodies is remarkably illustrative of the law of multiple proportions. The formulas of the acids are as follows: Thiosulphuric acid (Gr. Ociov, sulphur) is so called because it has the constitution of sulphuric acid with a molecule of oxygen replaced by one of sulphur. The last four acids in the table are called polythionic acids, because they contain varying proportions of sulphur united with constant proportions of the other elements. Sulphurous anhydride, SO2, formerly called sulphurous acid, is the only product when sulphur is burned in dry air or oxygen gas. When the combustion takes place in pure oxygen, it is found that on returning to its former temperature the gaseous product is doubled in weight, but that its volume is unchanged. It is in fact formed by the condensation of one volume of oxygen and half a volume of sulphur vapor into one volume. When required pure, sulphurous acid is usually obtained by the partial reduction of sulphuric acid. This is conveniently effected by boiling strong oil of vitriol with copper turnings or mercury. The reaction is shown in the following equation: Cu + 2H,SO, = CuS04+2H2O+SO2. It may also be obtained by passing the vapor of sulphuric acid over redhot platinum foil or sponge, the product being sulphurous anhydride and oxygen. (See OXYGEN, vol. xii., p. 769.) Sulphurous anhydride is a colorless gas, having a density of 2.21. When subjected to a pressure of three atmospheres at common temperatures, or if cooled to 0° F. at the ordinary pressure, it is condensed to a colorless, transparent liquid, which solidifies to a crystalline mass at -105°. The liquid anhydride may be obtained in large quantities by passing the gas from the generator first through a small quantity of water to wash it, then through a tube surrounded by ice to remove moisture, then through a tube containing pieces of calcium chloride to dry it completely, and finally through a worm, or into a receiver immersed in a mixture of salt and ice. It may be preserved in sealed glass tubes, or corked and wired soda bottles. Sulphurous anhydride dissolves in water, forming a solution of sulphurous acid, H2SO3, which again decomposes by the application of gentle heat into the anhydride and water. Water at 60° absorbs about 45 times its volume of the gas, the resulting liquid having a density of 104. By exposure to the air the solution slowly passes into sulphuric acid. By cooling a saturated aqueous solution to 32°, Döpping obtained the pure acid, H2SO,, in cubical crystals. A crystalline hydrate, SO,8H2O, according to Pierre, may also be obtained at a low temperature, which melts at 39°, suffering decomposition. Sulphurous acid is a powerful reducing agent, instantly discoloring acid solutions of manganates and chromates, reducing the latter to green oxides of chromium. It reduces the salts of gold, precipitating the metal in the metallic state, and is capable of taking the second molecule of oxygen from almost any metallic binoxide. Brewers often employ a solution of sulphurous acid to wash out their beer 458 SULPHURETTED HYDROGEN barrels, and in the rural districts sulphur is often burned in old cider barrels to purify them. Sulphurous acid is extensively used in bleaching straw, woollen, and silken goods, and also isinglass and other articles which would be injured by chlorine. (See BLEACHING.) It is a powerful antiseptic, and is now employed to preserve meats. (See PRESERVATION OF FOOD, vol. xiii., p. 824.) For its most important use, see SULPHURIC ACID. Sulphurous acid is dibasic, forming normal, neutral, and double salts. (See SULPHITES.) The binary compounds of sulphur with the metals, or the sulphides, are, when important, mentioned in the articles on the respective metals, or under SULPHIDES. One of the principal uses of sulphur is in making gunpowder. (See GUNPOWDER.)-Medical Properties and Uses. Sulphur is termed in therapeutics a laxative, diaphoretic, and alterative. It is supposed to be carried into the circulation by the fatty matters in the alimentary canal. That it is discharged by the skin is shown by the fact that silver worn about those who are taking it becomes blackened with a coating of sulphide. It is used in cutaneous and other diseases, both internally and externally, sometimes artificially prepared, and sometimes as it exists in natural springs. (See MINERAL SPRINGS.) It has been successfully employed in diphtheritic croup, given suspended in water, and in sciatica and chronic articular rheumatism, applied externally upon dry flannel and bandaged to the limb for several days. The officinal preparations embrace confections, plasters, and ointments, and precipitated sulphur or lac sulphuris. This latter preparation is made by boiling sulphur with milk of lime, which forms bisulphide of calcium and hyposulphite of lime, from the solutions of both of which the sulphur is precipitated by the action of hydrochloric acid. It has the general properties of ordinary sublimed sulphur, but is in a state of finer division. SULPHURETTED HYDROGEN. See HYDROSULPHURIC ACID. SULPHURIC ACID, the hydrate of sulphuric anhydride, or teroxide of sulphur, SO,+H,O= H.SO.. It may also be regarded as a salt of hydrogen, this element holding the place of a basyle to the radical sulphion, SO. (See SALTS, vol. xiv., pp. 582, 583.) The discovery of sulphuric acid is ascribed to Basil Valentine, a monk of Erfurt in Saxony, about 1440. He obtained it by distilling green vitriol or the sulphate of iron, and as the liquid product had an oily appearance when poured out, it was called oil of vitriol. He also obtained it by burning sulphur under a bell glass containing moisture, calling the product oleum sulphuris per campanum, or oil of sulphur by the bell. This was the germ of the present process of manufacture, which consists in producing sulphurous acid and carrying it to a higher state of oxidation by nitrous and hyponitrous acids. The old process of distilla red heat in earthen retorts placed in galleries in a furnace, as shown in fig. 1. As soon as the acid begins to distil over, the necks of the retorts are passed into receivers. The product is a brown oily liquid having a density of about 1.9, and fumes in the air, for which reason it is also called fuming sulphuric acid. Its composition may be expressed by the formula H2SO,,SOs. When gently heated it breaks up into sulphuric anhydride, SOs, and sulphuric acid, H2SO.. If fuming Nordhausen acid is distilled into a receiver cooled by ice, white fumes will solidify on its sides into white silky needles. This product was formerly called anhydrous sulphuric acid. It does not however possess acid properties like the residue in the retort, but requires to be united with water to enable it to combine with bases. It is tough and ductile, and can be moulded in the fingers for a short time if they are dry. It has a specific gravity of 1.946 at 55.4°, fumes in the air, and when thrown into water hisses like red-hot iron, and forms sulphuric acid. It melts at 65° and boils at about 95°, forming a colorless vapor, which is decomposed in highly heated porcelain tubes into two volumes of sulphurous anhydride and oxygen. The common way of preparing sulphuric acid at present, known as the English process, is to oxidize sulphurous acid. It is said to have been introduced by Dr. Roebuck about the middle of the 18th century, but the invention is also claimed for a calico printer at Rouen, with improvements by Chaptal, such claimants giving credit to Dr. Roebuck only for the invention of the leaden chambers in which the process was carried on. A large and long chamber, divided into sections by partitions which alternately leave open spaces at the top and bottom, has at one end a small furnace in which the flame of sulphur heats a crucible containing a mixture of nitre and oil of vitriol. The chamber is lined with sheet lead, and its floor is covered with a thin stratum of water. Jets of steam are also introduced. The sulphur in burning produces sulphurous anhydride, SO2, which in the presence of moisture becomes sulphurous acid (SO2+H2O=H2S0.), and this again, by the action of NOs, becomes sulphuric acid, H.SO., the nitric acid being at the same time reduced to a lower oxide. According to the researches of Weber and Winkler, the following is the rationale of the process: The oxidation of the sulphurous acid to sulphuric acid takes place in the leaden chambers under the influence of the vapor of water, at the expense of the oxygen of the nitric or nitrous acid, which is converted into deutoxide of nitrogen. It is necessary however that the nitrous acid be first absorbed in plenty of water, which takes up the free nitrous acid and decomposes the deutoxide of nitrogen, a process greatly promoted by the presence in the chamber of sulphurous acid purposely introduced. The water, usually in the form of steam (practical experience proving that a certain elevation of temperature is required), acts in this process as in others wherein sulphurous acid effects reduction. By the presence of atmospheric air in the chamber the deutoxide of nitrogen is oxidized into hyponitric or nitrous acid, and this acid again is decomposed by sulphurous acid. A peculiar crystalline substance sometimes forms, having the formula H2S04+N2O3,S0s, and formerly thought to play FIG. 2.-Class-room Apparatus for Sulphuric Acid. an important part in the transformation; but according to R. Weber this substance only appears when the process is not well managed, and is chiefly due to want of water. The process of forming sulphuric acid may be illustrated on a small scale by means of the apparatus shown in fig. 2. A flask, b, furnishes sulphurous anhydride, and the bottle e deutoxide of nitrogen, to the large glass balloon r, and the flask w supplies steam when it is required. Air is occasionally blown into the balloon through the bent tube t, the effete products passing out at o. If but little vapor of water is present, the white crystalline solid above mentioned makes its appearance upon the sides of the globe; but when sufficient water is present the substance is not deposited, neither is it supposed to be formed as a necessary stage of the process. Gay-Lussac invented what is called a condenser as an attachment to the large leaden chambers, for the purpose of economizing the consumption of nitre, which formerly amounted to from one eighth to one twelfth of the weight of sulphur. The condenser consists of a leaden tower filled with fragments of coke, through which sulphuric acid of 66° Baumé is constantly trickling. Through_this_condenser the spent gases are passed, and the oxides of nitrogen which they may contain are absorbed. The sulphuric acid which collects at the bottom of the chambers is too dilute for most purposes; it is not found advantageous to allow it to attain a specific gravity of quite 1.6, because at that strength it absorbs too much of the nitrous fumes. It may be used at this strength for the manufacture of salt cake (see SODA), but for other uses it must be further concentrated. This is generally effected by two different stages, the first in leaden pans, the second in platinum or glass retorts. Some makers concentrate to 60° Baumé (sp. gr. 1.71) in leaden pans; others use them only till the acid is raised to 55° Baumé (sp. gr. 1.59). The leaden pans are rectangular, long and wide, supported by iron plates to protect the lead from immediate contact with the flame which is used for evaporation. The pans are generally arranged in steps, the acid being conveyed from the upper to the lower ones by syphons, the density of the acid increasing from one pan to the next lower. When it has attained a density of from 1.65 to 1.72 in the leaden pans, it is known as brown oil of vitriol, and may be used by bleachers, calico printers, dyers, &c.; but to raise it to the strength of commercial oil of vitriol, it is further concentrated in the glass or platinum retorts above mentioned. Glass retorts holding 20 gallons or more are often used, set in an iron pot, the bottom of which is covered with dry sand. The concentration requires from 12 to 16 hours; the vapors which distil over toward the last, carrying some acid with them, are passed into condensers and returned to the lead pans. Platinum retorts are more costly, but are thought by many to be more economical in the end on account of their not being liable to break. Fig. 3 shows a section of a platinum retort. The syphon x is worked without a stopcock by the vessel c, in the following ingenious manner. When the vessel is lowered FIG. 3.-Platinum Retort. two definite hydrates, the monohydrate, H, SULPHURIC ETHER. See ETHER. SULPICIANS, or Priests of the Society of St. Salpice, a congregation of priests in the Roman head O communicates by means of tubing, not Catholic church founded in the parish of St. shown in the engraving, with a worm, where Sulpice, Paris, in 1645, by Jean Jacques Olier the watery vapor and the very weak acid me- de Verneuil, and specially devoted to the trainchanically carried over with it are condensed. ing of candidates for the priesthood. In 1642 The fire under the retort communicates with Olier and two other clergymen formed a comthe flue A, which passes under the leaden pans. munity at Vaugirard, and bound themselves to The concentrated acid left in the retorts con- found ecclesiastical seminaries. His compantains a slight excess of water beyond that ions soon abandoned him, and becoming in the required for the formula H2O,SO3 or H2SO4. same year rector of the parish of St. Sulpice, This formula gives 18.36 per cent. of the ele- he set about realizing his plan there. The act ments of water, while Marignac obtained 19-62 founding the society of St. Sulpice is dated per cent. from the concentrated acid. Accord- Sept. 6, 1645, and was immediately sanctioned ing to Playfair, if the concentration is con- by the proper authorities. The corner stone ducted at a temperature not exceeding 500° of the present seminary of St. Sulpice was laid F., the true compound, of sp. gr. 1.844, is ob- in September, 1649; the edifice was completed tained; but if heated to ebullition, there is and occupied in August, 1651. The society partial decomposition.-Properties. The oil formed two bands, the one devoted to parish of vitriol of commerce is an oily-looking, col-work, the other to that of teaching. The Sulorless, and odorless liquid, of sp. gr. 1-842. It picians were warmly befriended from the be chars nearly all organic substances, in conse- ginning by St. Vincent de Paul, and the estab quence of abstracting from them the elements lishment of Sulpician seminaries in nearly all of water, leaving a carbonaceous residue. It the dioceses of France soon followed. Theremixes with water in all proportions, with con- by the society came to have the chief part in densation of volume of the mixture, and con- the education of the French clergy down to the sequent evolution of heat. Its attraction for revolution of 1789. They were at first favored moisture is so great, that if exposed to the air by Napoleon, but were suppressed by him in for a few days in a shallow vessel it frequently 1812 for their attachment to Pius VII.; they doubles its weight; and advantage is taken of were restored by Louis XVIII., and ever afterthis in the laboratory for drying various sub- ward directed the most important diocesan stances. The boiling point of sulphuric acid seminaries in France.-Olier in 1636 formed a is 620-6° F., and it freezes at about -29°, al- company for colonizing the island of Montreal. though when frozen it does not melt below They purchased it in 1640, sent out Sieur de 32°. Marignac finds that the true sulphuric Maisonneuve with priests and nuns in 1641, and acid when heated parts with a small quantity transferred their proprietorship to the Sulpiof vapor of the anhydride, and the remaining cians in 1656. In 1657 the Sulpicians De Queyliquid boils at 640.4°. Sulphuric acid forms lus, Souard, and Galinier took possession of |