6. Chloric acid is decomposed, also, by sulphuretted hydrogen and by sulphurous acid. In the first case, chlorine and sulphur are separated, and water is formed. In the second, sulphuric acid is formed, and chlorine set at liberty. None of the acids, which are saturated with oxygen have any action on chloric acid.

7. All the metals that are capable of decomposing water, decompose also the chloric acid, and afford compounds of chlorine with a metallic oxide.

According to the experiments of Vauquelin, chloric acid is com

posed of

This determination differs materially from that of Gay Lussac, according to whom 32.304 oxygen convert 28.924 chlorine into chloric acid, and hence it should be composed of

The result of Gay Lussac is by much the more probable of the two, and would make the chloric consist of 1 atom of chlorine + 5 atoms of oxygen, while Vauquelin's numbers would indicate no less than 8 atoms of oxygen. Mr. Chenevix formerly stated the composition of the hyper-oxymuriatic or chloric acid to be 65 oxygen + 35 muriatic acid. To accommodate this view to the new theory, 10.4 taken from the oxygen and added to the muriatic acid will give 45.4 and 54.6, numbers not very different from those of Gay Lussac.

It is proper, however, to add that the existence of a simple combination of chlorine and oxygen has been denied by Sir H. Davy, who considers the liquid, obtained by Gay Lussac, as constituted of two proportions (atoms) of hydrogen, one of chlorine and six of oxygen. To this, the latter has replied, that the hydrogen is not an element of the acid itself, but of water with which the acid is united, as is the case with liquid sulphuric and nitric acids. The reader, who takes an interest in this controversy, may find it in the first volume of Annales de Chimie et de Physique, and of the Journal of Science and the Arts; and the argument for the existence of hydrogen in certain acids as an essential and acidifying principle, and not as a constituent of water, has, also, been ably supported by Dr. Murray, in a late volume of the Edinburgh Transactions.

Per-chloric Acid.

In obtaining peroxide of chlorine by Sir H. Davy's or by Count Stadion's process, a peculiar salt is formed, which was first noticed

by the latter philosopher. It is mixed with bisulphate of potash, which may be separated by a second crystallization, and the peculiar salt then appears in octohedral crystals. It requires 55 times its weight of water at 60° for solution, but dissolves freely in boiling water. In alcohol it is quite insoluble. When distilled with an equal weight of sulphuric acid, at a temperature of 280° Faht. it is decomposed: and an acid (of whose properties, however, we have not a distinct account) may be distilled over. When the salt is distilled alone at 412°, it is converted into chloride of potassium (dry muriate of potash) and oxygen gas, in the following proportions. One hundred parts by weight afford

Hence it appears that 25.59 chlorine are united with 45.92 oxygen, which is nearly in the proportion of 33.5 chlorine to 58 oxygen. Now to have agreed with the proportion of seven atoms of oxygen, the last mentioned number should have been 52.5; and if we suppose the oxygen a little over-rated, which may very probably be the case in a compound so imperfectly investigated, the per-chloric acid will then consist of one atom of chlorine 33.5, united with seven atoms of 52.5; and the weight of its atom will be 86.

oxygen =

=

SECTION III.

Chlorine with Nitrogen.

CHLORINE has no action whatsoever on nitrogen gas, nor on nitrous gas or nitrous oxide, when both gases are perfectly dry; but a compound of chlorine and nitrogen may be formed, by passing chlorine gas through a solution of nitrate of ammonia, or of almost any ammoniacal salt, of the temperature of 40° to 50° Fahrenheit. The chlorine gas is rapidly absorbed, and a film appears on the surface, which soon collects into yellowish drops, that sink to the bottom of the liquor.

This yellowish and oily fluid is the most powerfully detonating compound with which we are acquainted. When gently warmed, it explodes with so much violence, that it is not safe to employ a quantity larger than a grain of mustard seed. Its discoverer, M. Dulong,* was severely wounded in his first experiments on this substance; and Sir H. Davy had a serious injury done to his eyes in repeating them. It is expedient, therefore, to proceed with great caution.

* See Ann. de Chim. vol. 85.

When a globule of this fluid is thrown into olive oil, turpentine, or naphtha, it explodes even without heat, and so violently, as to shatter any glass vessel. The same effect ensues, when it touches phosphorus, or phosphorized alcohol or ether; but pure alcohol seems to deprive it of its explosive property, and renders it a white oily matter. The specific gravity of the fluid, Sir H. Davy has determined to be 1.653, water being 1. It is not congealed, by exposure to the cold produced by snow and muriate of lime.

The products of its detonation are chlorine and nitrogen gases, but it is impossible to determine the bulk of those elements which are afforded by a given weight. The best method of analyzing it, is by its action on mercury, which unites with the chlorine, and sets the nitrogen free. From various experiments of this kind, Sir H. Davy concludes that it is composed of four in volume of chlorine to one in volume of nitrogen, or of

These proportions correspond best with the opinion, that it is constituted of one atom of nitrogen to two atoms of chlorine; but the coincidence is not so exact, as in the case of some other compounds, and the analysis requires confirmation.

Chlorine and nitrous gases, separately dried by solid muriate of lime, do not combine on admixture; but when moisture is present, the chlorine decomposes water, forming muriatic acid with its hydrogen, while its oxygen condenses the nitrous gas.

SECTION IV.

Chlorine with the Metals of the Alkalies and Earths, and with the Oxides of those Metals.

WHEN potassium is heated in chlorine gas, it burns much more vividly than in oxygen; each grain absorbs 1.1 cubic inch of the gas, and a neutral compound is formed, precisely resembling that which results from heating potassium in dry muriatic acid gas. Sodium burns in chlorine with similar appearances, and condenses twice as much of the gas, as is absorbed by an equal weight of potassium.

When potassium or sodium, which have been made to absorb oxyn, are heated in chlorine gas, the latter disappears, and oxygen , precisely equivalent to what had been condensed, is liberated. ygen is expelled, also, by chlorine, from barytes, strontites, and e, in the proportion of one measure for every two measures of prine that are condensed.

s the oxygen is always evolved in its original quantity, though quantity of chlorine absorbed is variable, Sir H. Davy considers

this as proving that the oxygen does not proceed from the chlorine, but from the oxide; and that chlorine is a simple body, which attracts the metals in question more strongly than oxygen attracts them.

Ammonia is decomposed by chlorine, sometimes with detonation. If both gases are dry, no water is produced, which Sir H. Davy observes should happen, if chlorine contained oxygen; but the products are muriatic acid (from the union of the chlorine and hydrogen,) and nitrogen gas. The muriatic acid, with the undecomposed alkali, forms muriate of ammonia.

*

SECTION V.

Chlorine with Charcoal, Carbonic Oxide, and Carburetted Hydrogen.

WHEN the charcoal of beech wood, finely powdered and perfectly dry, is poured into chlorine gas in its ordinary state, an inflammation ensues. But charcoal, intensely ignited by the strongest powers of Voltaic electricity, in dry chlorine gas, effects no change, nor is any carbonic acid produced.t

Perfectly dry chlorine and light carburetted hydrogen gases, in the experiments of Dr. John Davy, detonated without producing carbonic acid. Muriatic acid gas was formed, and the charcoal was precipitated. But when the gases are fired over water, carbonic acid is obtained, the oxygen for which is furnished by the water. Mixtures of three or four parts of chlorine and one part of carburetted hydrogen over water, when exposed to the light of the sun, explode, and carbonic acid is generated; or, if the quantities are small, and indirect light only is admitted, the action of the gases goes on slowly, with similar results.

When three measures of chlorine are mixed with two and a half of olefiant gas or per-carburetted hydrogen, a white cloud appears, and, if the gases are pure, the whole is rapidly condensed. At the same time, a liquid resembling oil is formed, which has a greater specific gravity than water. From this property, per-carburetted hydrogen first received the name of olefiant gas; but it has been lately shown that the liquid obtained is analogous, not to oil but to ether, whence it has been called chloric ether. It will be described under that name in the second volume.

The condensation of per-carburetted hydrogen by chlorine gas affords an easy way of estimating the quantity of the former, in any mixture of it with hydrogen, light carburetted hydrogen, and carbonic oxide gases. Add to any gas, suspected to contain olefiant gas, about half its bulk of chlorine; if an immediate diminution ensue, accompanied with an evident production of an oily liquid, the presence of Children. Phil. Trans. 1815, p. 369.

* Phil. Trans. 1814, p. 70.

olefiant gas may be safely inferred. Of the whole quantity condensed, about 45 hundredths may be estimated to be per-carburetted hydrogen.

A mixture of equal volumes of chlorine and carbonic oxide gases, both dried by fused muriate of lime, and exposed, about a quarter of an hour, to bright sunshine, affords a peculiar compound, called by its discoverer, Dr. John Davy,* Phosgene Gas. The colour of the chlorine is destroyed by this combination, and the constituent gases are condensed into half their bulk. Hence it appears to be one of the heaviest gases known, 100 cubic inches being estimated to weigh 105.97 grains.

Phosgene gas has an intolerably pungent odour, and reddens litmus, whence it is called by some chemists phosgenic acid. Water changes it into muriatic and carbonic acid gases. The metals decompose it, and unite with the chlorine, a volume of carbonic oxide being liberated, equal to the bulk of the original gas. It condenses four times its volume of ammoniacal gas, and the product is a white neutral salt, from which the stronger acids disengage muriatic and carbonic acids; but acetic acid dissolves it without effervescence.

SECTION VI.

Chlorine with Sulphur and its Compounds.

SULPHUR, when heated in contact with chlorine gas, absorbs it, and forms a singular compound first described by Dr. Thomson.t Ten grains absorb nearly 30 cubic inches of gas, which is nearly in the proportion of 15 (the weight of an atom of sulphur) to 33.5 (the weight of an atom of chlorine). It appears, indeed, to be a true chloride of sulphur.

This fluid is volatile below 200° Fahrenheit. Its colour is red by reflected light, but yellowish green by transmitted light. It emits fumes, which are peculiarly acrid, and which excite a copious flow of tears. Its specific gravity is 1.6. It decomposes water, the hydrogen of which forms, with the chlorine, muriatic acid; while the sulphur, with the oxygen of the water, composes sulphuric acid. Before dilution, however, it is not acid, and does not redden dry litmus paper.

Dry chlorine gas has no action on dry sulphurous acid gas; but if water be present, muriatic and sulphuric acids result from their mixture.

When chlorine gas is mixed with sulphuretted hydrogen gas, the phenomena vary with the proportions. When equal bulks are used, there is scarcely any condensation, and the residue contains 19 twentieths of its bulk of muriatic acid gas. In this case sulphur is precipitated. But if enough of chlorine be used, besides the same product of muriatic acid, the sulphur is changed into chloride of sulphur. The compound of chlorine and phosphorus will be described in peaking of the latter substance.

*Phil. Trans. 1812.

† Nicholson's Journal, 8vo. vol. vi.