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How obtained.

Properties.

gravity of the strongest liquid when kept, in consequence dissolves iodine, becoming of

The liquid hydriodic acid hydrogen through a mixtur ed, and on heating and filt. acid is obtained, which m

260. That hydriodic and vapour of iodine is sorbing the iodine, evo gas.

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Iodine
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red heat, nor does it detonate when mixpected to the electric spark; but it may be some of the metals at high temperatures,

One volume of nitric oxide is thus resolvoxygen and nitrogen. If, therefore, we proportional of nitrogen + 1 oxy

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may be considered as consisting of 1 nitrogen+ 14 nitrogen + 16 oxygen, and its symbol will

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Nitric Oxide

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glowing charcoal plunged into nitric oxide gas is gemshed, but if it be passed through a porcelain tube charcoal, nitrogen and carbonic acid and oxide are

aofygen, the deutox, nitrogen -0.9375-this so, (atom of oxygen being = 1)-further 3.75 is just 30 multiplied

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271. Nitric Oxide and Chlorine, when both are perfectly dry, exert no mutual action, but the presence of water causes an immediate change; it is decomposed, and, furnishing oxygen to the nitric oxide, and hydrogen to the chlorine, nitrous acid and muriatic acid gases are generated. It was the presence of water which misled those, who thought that the red fumes produced by mixing nitric oxide and chlorine not carefully dried, resulted from the existence of oxygen in chlorine.

212. Gay-Lussac has concluded from his experiments that there exists a compound of nitrogen and oxygen intermediate between nitric oxide and nitrous acid, which he has termed per-nitrous acid, but to which the term hyponitrous acid is more applicable. He considers it as a compound of i proportional of nitrogen, and 3 of oxygen; but the existence of such a compound can scarcely be considered as accurately demonstrated.

273. Nitrous Acid Gas. When nitric oxide is presented to oxygen, the two gases combine, and a new gaseous compound of a deep orange colour results. This compound is not easily examined, because it is absorbed both by quicksilver and water, so that we are obliged to resort to exhausted glass vessels for its production. When we thus mix two volumes of nitric oxide with one volume of oxygen, the gases become condensed to about half their original volume, and form nitrous acid gas.

This gas supports the combustion of the taper, of phosphorus, and of charcoal, but extinguishes sulphur. It is readily absorbed by water forming a green sour liquid. Its specific gravity to hydrogen is as 23 to 1, and 100 cubic inches weigh 48.69 grains.*

274. It is obvious that this nitrous acid gas must consist of 14 nitrogen + 32 oxygen, and therefore, its number is 46; for nitric oxide is composed of equal volumes of nitrogen and oxygen, and one additional volume of oxygen, or two proportionals by weight are added to form

nitrous acid.

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275. If the mixture of nitric oxide and oxygen be made over water, in the above proportions, and if the gases be perfectly pure, complete

*Specific gravity of oxygen being =1; that of nitrous acid gas will be 2.875, this multiplied by 2 will give 5.75 for the atom when that of oxygen =1, also, 5,75 is just 46 times 0,125 (the atom of hydrogen.)

space of two volumes. The specific gravity of nitrogen compared with oxygen, is as 14 to 16; nitrous oxide, therefore, consists of

14 Nitrogen 8 Oxygen

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268. Nitric oxide, deutoxide of nitrogen, or nitrous gas, is usually obtained by presenting certain substances to nitric acid, which abstract a portion of its oxygen, leaving the remaining elements in such proportions as to constitute the gas in question; for this purpose some copper filings may be put into a gas bottle (227) with nitric acid, diluted with thrice its bulk of water; an action ensues red fumes are produced, and there is a copious evolution of the gas, which may be collected and preserved over water. The first portions should be rejected as containing nitrogen and nitrous acid gas. Nitric oxide is presently recognised by the red fumes which it produces when brought into the contact of air.

* Its specific gravity to hydrogen is as 15 to 1. 100 cubic inches weigh 31.755 grains. When it has been washed with water it is not acid, as may be proved by the colour of litmus remaining unchanged by it. It extinguishes most burning bodies, but phosphorus readily burns in it, if introduced in intense ignition.

269. It is not altered by a red heat, nor does it detonate when mixed with hydrogen, and subjected to the electric spark; but it may be decomposed by the action of some of the metals at high temperatures, which absorb its oxygen. One volume of nitric oxide is thus resolved into equal volumes of oxygen and nitrogen. If, therefore, we call nitrous oxide a compound of 1 proportional of nitrogen + 1 oxygen, then nitric oxide may be considered as consisting of 1 nitrogen+ 2 oxygen, or by weight, 14 nitrogen + 16 oxygen, and its symbol will stand thus:

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270. A piece of glowing charcoal plunged into nitric oxide gas is presently extinguished, but if it be passed through a porcelain tube containing red-hot charcoal, nitrogen and carbonic acid and oxide are produced.

* When the specific gravity of oxygen-1, the deutox. nitrogen = 0.9375-this multiplied by 4 gives 3.75 for its atom, (atom of oxygen being = 1)-further 3.75 is just 30 times, 125 (the atom of hydrogen.)

271. Nitric Oxide and Chlorine, when both are perfectly dry, exert no mutual action, but the presence of water causes an immediate change; it is decomposed, and, furnishing oxygen to the nitric oxide, and hydrogen to the chlorine, nitrous acid and muriatic acid gases are generated. It was the presence of water which misled those, who thought that the red fumes produced by mixing nitric oxide and chlorine not carefully dried, resulted from the existence of oxygen in chlorine.

272. Gay-Lussac has concluded from his experiments that there exists a compound of nitrogen and oxygen intermediate between nitric oxide and nitrous acid, which he has termed per-nitrous acid, but to which the term hyponitrous acid is more applicable. He considers it as a compound of i proportional of nitrogen, and 3 of oxygen; but the existence of such a compound can scarcely be considered as accurately demonstrated.

273. Nitrous Acid Gas. When nitric oxide is presented to oxygen, the two gases combine, and a new gaseous compound of a deep orange colour results. This compound is not easily examined, because it is absorbed both by quicksilver and water, so that we are obliged to resort to exhausted glass vessels for its production. When we thus mix two volumes of nitric oxide with one volume of oxygen, the gases become condensed to about half their original volume, and form nitrous acid gas.

This gas supports the combustion of the taper, of phosphorus, and of charcoal, but extinguishes sulphur. It is readily absorbed by water forming a green sour liquid. Its specific gravity to hydrogen is as 23 to 1, and 100 cubic inches weigh 48.69 grains.*

274. It is obvious that this nitrous acid gas must consist of 14 nitrogen + 32 oxygen, and therefore, its number is 46; for nitric oxide is composed of equal volumes of nitrogen and oxygen, and one additional volume of oxygen, or two proportionals by weight are added to form nitrous acid.

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275. If the mixture of nitric oxide and oxygen be made over water, in the above proportions, and if the gases be perfectly pure, complete

* Specific gravity of oxygen being =1; that of nitrous acid gas will be 2.875, this multiplied by 2 will give 5.75 for the atom when that of oxygen =1, also, 5,75 is just 46 times 0,125 (the atom of hydrogen.)

absorption takes place; but if either the oxygen or nitric oxide contain uncombined nitrogen it will remain unabsorbed.

276. Nitric Acid. - The fourth compound of nitrogen with oxygen is the nitric acid; the nature of which was first demonstrated by Mr. • Cavendish in 1785. (Phil. Trans.) It is usually obtained by the distillation of purified nitre with sulphuric acid, of which materials different proportions are employed. The nitric acid of commerce, which is generally red and fuming in consequence of the presence of nitric oxide, is procured by the distillation of two parts of nitre with one of sulphuric acid; these proportions afford about one part of orange-coloured nitric acid of the specific gravity of 1.48. Upon the large scale 112 lbs. of nitre, and 56 of sulphuric acid yield from 50 to 52 lbs. of nitric acid. Some manufacturers employ three parts of nitre and two of sulphuric acid, and the London Pharmacopaia directs equal weights, by which a nearly colourless nitric acid is afforded.

It will appear by referring to the article Sulphuric Acid, that it contains in its liquid state one proportional of dry acid, and one of water; whereas liquid nitric acid contains one proportional of dry acid, and two of water; hence the requisite excess of sulphuric acid, where colourless and perfect nitric acid is to be obtained; hence too the red colour of the acid of commerce in consequence of the smaller quantity of sulphuric acid generally used by the manufacturer. This will be more apparent by reference to the article Bi-sulphate of Potassa.

The distillation of nitric acid may be conducted upon the small scale in a tubulated glass retort a, with a tubulated receiver 6, passing into the bottle с. The requisite heat is obtained by the lamp d, and the whole apparatus supported by the brass stands with sliding rings e e.

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Preparation of But the manufacturer who prepares nitric acid upon a large scale, nitrous acid. generally employs distillatory vessels of stone-ware. The following wood-cut represents the arrangement of the distillatory apparatus, employed at Apothecaries' Hall, for the production of common aqua

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