Elements of Chemistry Part 13

{Nitrous acid Smoaking nitrous acid.

Oxygen {Nitric acid Pale nitrous acid.

{Oxygenated nitric acid Unknown.

{This combination is. .h.i.therto unknown; should it {ever be discovered, it will be called, according to Charcoal {the principles of our nomenclature, Azuret of {Charcoal. Charcoal dissolves in azotic gas, and {forms carbonated azotic gas.

Phosphorus. Azuret of phosphorus. Still unknown.

{Azuret of sulphur. Still unknown. We know Sulphur {that sulphur dissolves in azotic gas, forming {sulphurated azotic gas.

{Azote combines with charcoal and hydrogen, and Compound {sometimes with phosphorus, in the compound radicals {oxydable and acidifiable bases, and is generally {contained in the radicals of the animal acids.

{Such combinations are hitherto unknown; if ever Metallic {discovered, they will form metallic azurets, as substances {azuret of gold, of silver, &c.

Lime { Magnesia { Barytes {Entirely unknown. If ever discovered, they will Argill {form azuret of lime, azuret of magnesia, &c.

Potash { Soda {

SECT. VI.--_Observations upon the Combinations of Azote with the Simple Substances._

Azote is one of the most abundant elements; combined with caloric it forms azotic gas, or mephitis, which composes nearly two thirds of the atmosphere. This element is always in the state of gas in the ordinary pressure and temperature, and no degree of compression or of cold has been hitherto capable of reducing it either to a solid or liquid form.

This is likewise one of the essential const.i.tuent elements of animal bodies, in which it is combined with charcoal and hydrogen, and sometimes with phosphorus; these are united together by a certain portion of oxygen, by which they are formed into oxyds or acids according to the degree of oxygenation. Hence the animal substances may be varied, in the same way with vegetables, in three different manners: 1st, According to the number of elements which enter into the composition of the base or radical: 2dly, According to the proportions of these elements: 3dly, According to the degree of oxygenation.

When combined with oxygen, azote forms the nitrous and nitric oxyds and acids; when with hydrogen, ammoniac is produced. Its combinations with the other simple elements are very little known; to these we give the name of Azurets, preserving the termination in _uret_ for all nonoxygenated compounds. It is extremely probable that all the alkaline substances may hereafter be found to belong to this genus of azurets.

The azotic gas may be procured from atmospheric air, by absorbing the oxygen gas which is mixed with it by means of a solution of sulphuret of potash, or sulphuret of lime. It requires twelve or fifteen days to complete this process, during which time the surface in contact must be frequently renewed by agitation, and by breaking the pellicle which forms on the top of the solution. It may likewise be procured by dissolving animal substances in dilute nitric acid very little heated.

In this operation, the azote is disengaged in form of gas, which we receive under bell gla.s.ses filled with water in the pneumato-chemical apparatus. We may procure this gas by deflagrating nitre with charcoal, or any other combustible substance; when with charcoal, the azotic gas is mixed with carbonic acid gas, which may be absorbed by a solution of caustic alkali, or by lime water, after which the azotic gas remains pure. We can procure it in a fourth manner from combinations of ammoniac with metallic oxyds, as pointed out by Mr de Fourcroy: The hydrogen of the ammoniac combines with the oxygen of the oxyd, and forms water, whilst the azote being left free escapes in form of gas.

The combinations of azote were but lately discovered: Mr Cavendish first observed it in nitrous gas and acid, and Mr Berthollet in ammoniac and the prussic acid. As no evidence of its decomposition has. .h.i.therto appeared, we are fully ent.i.tled to consider azote as a simple elementary substance.

TABLE _of the Binary Combinations of Hydrogen with Simple Substances._

_Simple_ _Resulting Compounds._ _Substances._ _New Nomenclature._ _Old Names._

Caloric Hydrogen gas Inflammable air.

Azote Ammoniac Volatile Alkali.

Oxygen Water Water.

Sulphur {Hydruret of sulphur, or } {sulphuret of hydrogen } Hitherto unknown (A).

Phosphorus {Hydruret of phosphorus, or } {phosphuret of hydrogen }

Charcoal {Hydro-carbonous, or } Not known till lately.

{carbono-hydrous radicals(B)}

Metallic {Metallic hydrurets(C), as } Hitherto unknown.

substances, {hydruret of iron, &c. } as iron, &c. { }

[Note A: These combinations take place in the state of gas, and form, respectively, sulphurated and phosphorated oxygen gas--A.]

[Note B: This combination of hydrogen with charcoal includes the fixed and volatile oils, and forms the radicals of a considerable part of the vegetable and animal oxyds and acids. When it takes place in the state of gas it forms carbonated hydrogen gas.--A.]

[Note C: None of these combinations are known, and it is probable that they cannot exist, at least in the usual temperature of the atmosphere, owing to the great affinity of hydrogen for caloric.--A.]

SECT. VII.--_Observations upon Hydrogen, and its Combinations with Simple Substances._

Hydrogen, as its name expresses, is one of the const.i.tuent elements of water, of which it forms fifteen hundredth parts by weight, combined with eighty-five hundredth parts of oxygen. This substance, the properties and even existence of which was unknown till lately, is very plentifully distributed in nature, and acts a very considerable part in the processes of the animal and vegetable kingdoms. As it possesses so great affinity with caloric as only to exist in the state of gas, it is consequently impossible to procure it in the concrete or liquid state, independent of combination.

To procure hydrogen, or rather hydrogen gas, we have only to subject water to the action of a substance with which oxygen has greater affinity than it has to hydrogen; by this means the hydrogen is set free, and, by uniting with caloric, a.s.sumes the form of hydrogen gas.

Red hot iron is usually employed for this purpose: The iron, during the process, becomes oxydated, and is changed into a substance resembling the iron ore from the island of Elba. In this state of oxyd it is much less attractible by the magnet, and dissolves in acids without effervescence.

Charcoal, in a red heat, has the same power of decomposing water, by attracting the oxygen from its combination with hydrogen. In this process carbonic acid gas is formed, and mixes with the hydrogen gas, but is easily separated by means of water or alkalies, which absorb the carbonic acid, and leave the hydrogen gas pure. We may likewise obtain hydrogen gas by dissolving iron or zinc in dilute sulphuric acid. These two metals decompose water very slowly, and with great difficulty, when alone, but do it with great ease and rapidity when a.s.sisted by sulphuric acid; the hydrogen unites with caloric during the process, and is disengaged in form of hydrogen gas, while the oxygen of the water unites with the metal in the form of oxyd, which is immediately dissolved in the acid, forming a sulphat of iron or of zinc.

Some very distinguished chemists consider hydrogen as the _phlogiston_ of Stahl; and as that celebrated chemist admitted the existence of phlogiston in sulphur, charcoal, metals, &c. they are of course obliged to suppose that hydrogen exists in all these substances, though they cannot prove their supposition; even if they could, it would not avail much, since this disengagement of hydrogen is quite insufficient to explain the phenomena of calcination and combustion. We must always recur to the examination of this question, "Are the heat and light, which are disengaged during the different species of combustion, furnished by the burning body, or by the oxygen which combines in all these operations?" And certainly the supposition of hydrogen being disengaged throws no light whatever upon this question. Besides, it belongs to those who make suppositions to prove them; and, doubtless, a doctrine which without any supposition explains the phenomena as well, and as naturally, as theirs does by supposition, has at least the advantage of greater simplicity[40].

TABLE _of the Binary Combinations of Sulphur with Simple Substances._

_Simple_ _Resulting Compounds._ _Substances._ _New Nomenclature._ _Old Nomenclature._

Caloric Sulphuric gas

{ Oxyd of sulphur Soft sulphur.

Oxygen { Sulphurous acid Sulphureous acid.

{ Sulphuric acid Vitriolic acid.

Hydrogen Sulphuret of hydrogen } Azote azote } Unknown Combinations.

Phosphorus phosphorus } Charcoal charcoal }

Antimony antimony Crude antimony.

Silver silver a.r.s.enic a.r.s.enic Orpiment, realgar.

Bis.m.u.th bis.m.u.th Cobalt cobalt Copper copper Copper pyrites.

Tin tin Iron iron Iron pyrites.

Manganese manganese Mercury mercury Ethiops mineral, cinnabar.

Molybdena molybdena Nickel nickel Gold gold Platina platina Lead lead Galena.

Tungstein tungstein Zinc zinc Blende.

{ Alkaline liver of sulphur Potash potash { with fixed vegetable alkali.

{ Alkaline liver of sulphur Soda soda { with fixed mineral { alkali.

{ Volatile liver of sulphur, Ammoniac ammoniac { smoaking liquor { of Boyle.

Lime lime Calcareous liver of sulphur.

Magnesia magnesia Magnesian liver of sulphur.

Barytes barytes Barytic liver of sulphur.

Argill argill Yet unknown.