mass of radiated crystals. The same substance has also been remarked as occasionally formed in the acid of the English manufacturers. It has been called glacial or fuming sulphuric acid, and is by Dr. Thomson considered as the pure or anhydrous acid; it appears, however, probable, that it consists of sulphuric acid, combined with a portion of sulphurous acid.-See Sulphate of Iron (738.)

325. It has long been an object with the manufacturer to obtain sulphuric acid without the aid of nitre, and a patent has been obtained for a process of this kind, invented by Mr. Hill. It consists in submitting coarsely-powdered iron pyrites (737) (sulphuret of iron,) to a red heat, in cylinders communicating with a leaden chamber containing water; the sulphur, as it burns out of the pyrites, appears at once to pass into the state of sulphuric acid.

326. Native Sulphuric Acid has been found by Professor Baldassari, in the cavities of a small volcanic hill, called Zoccolino, near Sienna. 327. When sulphuric acid is dropped into a concentrated and hot solution of iodic acid, a peculiar compound is formed, which may be termed iodo-sulphuric acid; it is yellow, fusible, and crystallizes on acid. cooling in rhomboids; at a higher temperature it partly sublimes, and is partly decomposed.

Iodo-sulphuric

328. Sulphuric Acid and Ammonia-Sulphate of Ammonia-may be obtained by passing ammonia into sulphuric acid; but it is usually pre- Sulphate of pared by saturating dilute sulphuric acid with carbonate of ammonia, or ammonia. by decomposing muriate of ammonia by sulphuric acid. It is the secret sal-ammoniac of some old writers. This salt is important as a source of the muriate of ammonia, (292) which is obtained by sublimation from a mixture of common salt and sulphate of ammonia; by this process sulphate of soda is also formed.

Sulphate of ammonia dissolves in twice its weight of water at 60o, and consists of 1 proportional of sulphuric acid =40 + 1 proportional of ammonia = 17. Its number, therefore, is 57. By crystallization it affords six-sided prisms. Its taste is bitter and pungent. When heated, it melts and in part sublimes, ammonia is given off, and a supersulphate remains, consisting of 2 proportionals of acid + 1 of alcali.

329. Native Sulphate of Ammonia is sometimes found in volcanic products; it occurs in stalactitic concretions of a whitish or yellowish colour, and covered with a white efflorescence: it has thus been procured from fissures in the earth surrounding certain small lakes in Tuscany, near Sienna; and among the products of Etna and Vesuvius; it has been termed by Karsten Mascagnine, from the name of its dis

coverer.

330. Sulphur and Chlorine-Chloride of Sulphur. This compound was first described by Dr. Thomson, in 1804 (NICHOLSON'S Journal, Chloride of Vol. vii.) When sulphur is heated in chlorine, it absorbs rather more than twice its weight of that gas. 10 grains of sulphur absorb 30 cubic inches of chlorine, and produce a greenish-yellow liquid, consisting of 16 sulphur + 36.0 chlorine, and represented, therefore, by the number 52. It exhales suffocating and irritating fumes when exposed to the air. Its specific gravity is 1.6. It does not affect dry vegetable blues; but when water is present, it instantly reddens them, sulphur is deposited and sulphurous, sulphuric, and muriatic acids are

Analysis of

Sulphuric acid.

322. The decomposition of sulphuric acid may be effected by passsulphuric acid. ing it through a red-hot platinum tube, when it is resolved into sulphu

Uses.

rous acid, oxygen, and water.

When heated with charcoal, sulphuric acid gives rise to the production of carbonic and sulphurous acids; with phosphorus it produces phosphoric and sulphurous acids; and, with sulphur, sulphurous acid is the only product. It is decomposed by several of the metals, which become oxidized, and evolve sulphurous acid, as shown in the production of this acid, by boiling sulphuric acid with mercury (313), tin, lead, &c.

323. Sulphuric acid is largely consumed in a variety of manufactures. It is used by the makers of nitric, muriatic, citric, and tartaric acids; by bleachers, dyers, tin-plate makers, brass-founders and gilders. For these purposes it is generally sufficiently pure as it comes from the wholesale manufacturer; but, as traces of lead, lime, and potassa, are usually found in it, it often requires to be purified by distillation for the use of the experimental chemist.

The distillation of this acid in glass retorts requires some precaution, in consequence of the violent jerks which the production of its vapour occasions, and which often break the vessel; this may be prevented by putting some strips of platinum into the acid; it then boils quietly. and it is only necessary to take care that the neck of the retort and receiver are not broken in consequence of the high temperature of the condensing acid. This very useful contrivance to the practical chemist was first shown me by Mr. James South.

If the acid of commerce contain dissolved sulphate of lead, it becomes turbid on dilution, so that its remaining clear when mixed with water, is some proof of its purity, as far at least as lead is concerned. 324. When sulphuric acid was procured by the distillation of green vitriol, it was frequently observed that a portion concreted into a white mass of radiated crystals. The same substance has also been remarked as occasionally formed in the acid of the English manufacturers. It has been called glacial or fuming sulphuric acid, and is by Dr. Thomson considered as the pure or anhydrous acid; it appears, however, probable, that it consists of sulphuric acid, combined with a portion of sulphurous acid.-See Sulphate of Iron (738.)

325. It has long been an object with the manufacturer to obtain sulphuric acid without the aid of nitre, and a patent has been obtained for a process of this kind, invented by Mr. Hill. It consists in submitting coarsely-powdered iron pyrites (737) (sulphuret of iron,) to a red heat, in cylinders communicating with a leaden chamber containing water; the sulphur, as it burns out of the pyrites, appears at once to pass into the state of sulphuric acid.

326. Native Sulphuric Acid has been found by Professor Baldassari, in the cavities of a small volcanic hill, called Zoccolino, near Sienna. 327. When sulphuric acid is dropped into a concentrated and hot solution of iodic acid, a peculiar compound is formed, which may be termed iodo-sulphuric acid; it is yellow, fusible, and crystallizes on acid. cooling in rhomboids; at a higher temperature it partly sublimes, and is partly decomposed.

Iodo-sulphuric

328. Sulphuric Acid and Ammonia-Sulphate of Ammonia-may be obtained by passing ammonia into sulphuric acid; but it is usually pre- Sulphate of pared by saturating dilute sulphuric acid with carbonate of ammonia, or ammonia. by decomposing muriate of ammonia by sulphuric acid. It is the secret sal-ammoniac of some old writers. This salt is important as a source of the muriate of ammonia, (292) which is obtained by sublimation from a mixture of common salt and sulphate of ammonia; by this process sulphate of soda is also formed.

Sulphate of ammonia dissolves in twice its weight of water at 60°, and consists of 1 proportional of sulphuric acid =40 + 1 proportional of ammonia = 17. Its number, therefore, is 57. By crystallization it affords six-sided prisms. Its taste is bitter and pungent. When heated, it melts and in part sublimes, ammonia is given off, and a supersulphate remains, consisting of 2 proportionals of acid + 1 of alcali.

329. Native Sulphate of Ammonia is sometimes found in volcanic products; it occurs in stalactitic concretions of a whitish or yellowish colour, and covered with a white efflorescence: it has thus been procured from fissures in the earth surrounding certain small lakes in Tuscany, near Sienna; and among the products of Etna and Vesuvius ; it has been termed by Karsten Mascagnine, from the name of its dis

coverer.

330. Sulphur and Chlorine-Chloride of Sulphur. This compound was first described by Dr. Thomson, in 1804 (NICHOLSON'S Journal, Chloride of Vol. vii.) When sulphur is heated in chlorine, it absorbs rather more than twice its weight of that gas. 10 grains of sulphur absorb 30 cubic inches of chlorine, and produce a greenish-yellow liquid, consisting of 16 sulphur + 36.0 chlorine, and represented, therefore, by the number 52. It exhales suffocating and irritating fumes when exposed to the air. Its specific gravity is 1.6. It does not affect dry vegetable blues; but when water is present, it instantly reddens them, sulphur is deposited and sulphurous, sulphuric, and muriatic acids are

phur.

Sulphuretted hydrogen.

formed in consequence of a decomposition of the water. It dissolves sulphur and phosphorus.

lodide of sul- 331. Sulphur and Iodine readily unite and form a black crystallizable compound, first described by M. Gay-Lussac. Annales de Chimie, 91. 332. Sulphur and Hydrogen Sulphuretted Hydrogen gas-Hydrothionic acid. This gaseous compound of sulphur and hydrogen was discovered by Scheele in 1777. It may be obtained by presenting sulphur to nascent hydrogen, which is the case when sulphuret of iron is acted upon by dilute sulphuric acid. It may also be conveniently obtained by heating bruised sulphuret of antimony in muriatic acid.

333. Sulphuretted hydrogen gas may be collected over water, though, by agitation, that fluid absorbs nearly thrice its bulk. It has a peculiarly nauseous fetid odour, resembling that of rotten eggs. Its specific gravity* to hydrogen is as 17 to 1. 100 cubic inches weigh 36 grains. It is inflammable, and during its slow combustion, sulphur is deposited, and water and sulphurous acid formed. It extinguishes flame. When respired, it proves fatal; and it is very deleterious, even though largely diluted with atmospheric air. It exists in some mineral

waters.

334. The aqueous solution of sulphuretted hydrogen is transparent and colourless, but if exposed to air it deposits sulphur and the gas escapes. It is an exceedingly delicate test of the presence of most of the metals, with which it forms coloured precipitates. It reddens infusion of litmus; and as it combines with the greater number of salifiable bases, it has by some been regarded as an acid. Gay-Lussac has termed it hydrosulphuric acid.

335. When one volume of sulphuretted hydrogen, and 1.5 of oxygen are inflamed in a detonating tube, 1 volume of sulphurous acid is produced, and water is formed. Thus the sulphur is transferred to 1 volume of the oxygen, and the hydrogen to the half volume. Sulphuretted hydrogen, therefore, consists of 16 sulphur + 1 hydrogen, and its number is 17. Sulphuretted hydrogen may also be decomposed by the Voltaic flame, in the apparatus shown at page 80, or by a succession of electric sparks. Its volume is unchanged, but the sulphur is thrown down.

336. Chlorine and iodine instantly decompose sulphuretted hydrogen; sulphur is deposited, and muriatic (248) and hydriodic (259) acids are formed. It is also decomposed by the metal potassium, which absorbs the sulphur and liberates pure hydrogen, when heated in the gas. Nitric acid poured into the gas occasions a deposition of sulphur, and nitrous acid and water are formed.

337. When sulphuretted hydrogen is mixed with its volume of nitric oxide over mercury, a diminution of bulk ensues, in consequence of the production of water; sulphur is deposited and nitrous oxide remains in the vessel.

338. When two volumes of sulphuretted hydrogen are mixed in an exhausted balloon with one of sulphurous acid, they mutually decompose each other, occasioning the production of water, and the deposıtion of sulphur; if the gases be perfectly dry, the action is slow.

* When the specific gravity of oxygen = 1; that of sulph. hydrogen = 1.0625, now twice this or 2.125 is the atom, and 2.125 is just 17 times 0.125 (the atom of hydrogen.)

nia.

ammo

339. Sulphuretted hydrogen and ammonia readily unite in equal volumes, and produce hydrosulphuret of ammonia. At first white fumes Hydrosulphuappear, which become yellow, and a yellow crystallized compound results, consisting of 17 sulphuretted hydrogen, + 17 ammonia. It is of much use as a test for the metals, and may be procured by distilling at nearly a red heat, a mixture of 6 parts of slacked lime, 2 of muriate of ammonia, and 1 of sulphur.

340. The following is the disposition of the apparatus for this experiment: a, a small furnace: b, a tubulated earthen retort containing the above materials; c, an adapting tube; e, a glass balloon for condensing the vapour; f, a receiver; g, a bottle of water, into which the glass tube, issuing from the upper part of the receiver, e, is made to dip about half an inch.

The product in the bottle f may be mixed with the water ing, and the whole used for washing out the receiver e. In its concentrated state, this compound exhales white fumes, as was first remarked by Boyle, whence it was termed Boyle's Fuming Liquor, or Volatile Liver of Sulphur. It is a deep yellow liquid, smelling like a mixture of sulphuretted hydrogen and ammonia.

When kept in common white glass vessels it renders them brown or black, in consequence of its action on the oxide of lead which the glass

contains.

341. Another compound of hydrogen and sulphur which has been called supersulphuretted hydrogen, is described in most books as a liquid formed by adding muriatic acid to a solution of sulphuret of potassa, and it is said to consist of two proportionals of sulphur = 32 + 1 of hydrogen = 1. I have, however, never been able to obtain it.

342. Sulphur and Nitrogen do not form any definite compound, though the nitrogen evolved during the decomposition of certain animal substances, often seems to contain sulphur.

343. Sulphur, in its ordinary state, always contains hydrogen, which it gives off during the action of various bodies for which it has a powerful attraction. Thus, if equal weights of sulphur and copper or iron-filings be introduced into a retort, and heated, a quantity of hydrogen, mixed with sulphuretted hydrogen, is evolved at the period of their combination.