Elements of Chemistry Part 14

SECT. VIII.--_Observations on Sulphur, and its Combinations._

Sulphur is a combustible substance, having a very great tendency to combination; it is naturally in a solid state in the ordinary temperature, and requires a heat somewhat higher than boiling water to make it liquify. Sulphur is formed by nature in a considerable degree of purity in the neighbourhood of volcanos; we find it likewise, chiefly in the state of sulphuric acid, combined with argill in aluminous schistus, with lime in gypsum, &c. From these combinations it may be procured in the state of sulphur, by carrying off its oxygen by means of charcoal in a red heat; carbonic acid is formed, and escapes in the state of gas; the sulphur remains combined with the clay, lime, &c. in the state of sulphuret, which is decomposed by acids; the acid unites with the earth into a neutral salt, and the sulphur is precipitated.

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

_Simple Substances._ _Resulting Compounds._

Caloric Phosphoric gas.

{ Oxyd of phosphorus.

Oxygen { Phosphorous acid.

{ Phosphoric acid.

Hydrogen Phosphuret of hydrogen.

Azote Phosphuret of azote.

Sulphur Phosphuret of Sulphur.

Charcoal Phosphuret of charcoal.

Metallic substances Phosphuret of metals(A).

Potash } Soda } Ammoniac } Phosphuret of Potash, Lime } Soda, &c.(B) Barytes } Magnesia } Argill }

[Note A: Of all these combinations of phosphorus with metals, that with iron only is. .h.i.therto known, forming the substance formerly called Siderite; neither is it yet ascertained whether, in this combination, the phosphorus be oxygenated or not.--A.]

[Note B: These combinations of phosphorus with the alkalies and earths are not yet known; and, from the experiments of Mr Gengembre, they appear to be impossible--A.]

SECT. IX.--_Observations upon Phosphorus, and its Combinations._

Phosphorus is a simple combustible substance, which was unknown to chemists till 1667, when it was discovered by Brandt, who kept the process secret; soon after Kunkel found out Brandt's method of preparation, and made it public. It has been ever since known by the name of Kunkel's phosphorus. It was for a long time procured only from urine; and, though Homberg gave an account of the process in the Memoirs of the Academy for 1692, all the philosophers of Europe were supplied with it from England. It was first made in France in 1737, before a committee of the Academy at the Royal Garden. At present it is procured in a more commodious and more oeconomical manner from animal bones, which are real calcareous phosphats, according to the process of Messrs Gahn, Scheele, Rouelle, &c. The bones of adult animals being calcined to whiteness, are pounded, and pa.s.sed through a fine silk sieve; pour upon the fine powder a quant.i.ty of dilute sulphuric acid, less than is sufficient for dissolving the whole. This acid unites with the calcareous earth of the bones into a sulphat of lime, and the phosphoric acid remains free in the liquor. The liquid is decanted off, and the residuum washed with boiling water; this water which has been used to wash out the adhering acid is joined with what was before decanted off, and the whole is gradually evaporated; the dissolved sulphat of lime cristallizes in form of silky threads, which are removed, and by continuing the evaporation we procure the phosphoric acid under the appearance of a white pellucid gla.s.s. When this is powdered, and mixed with one third its weight of charcoal, we procure very pure phosphorus by sublimation. The phosphoric acid, as procured by the above process, is never so pure as that obtained by oxygenating pure phosphorus either by combustion or by means of nitric acid; wherefore this latter should always be employed in experiments of research.

Phosphorus is found in almost all animal substances, and in some plants which give a kind of animal a.n.a.lysis. In all these it is usually combined with charcoal, hydrogen, and azote, forming very compound radicals, which are, for the most part, in the state of oxyds by a first degree of union with oxygen. The discovery of Mr Ha.s.senfratz, of phosphorus being contained in charcoal, gives reason to suspect that it is more common in the vegetable kingdom than has generally been supposed: It is certain, that, by proper processes, it may be procured from every individual of some of the families of plants.

As no experiment has. .h.i.therto given reason to suspect that phosphorus is a compound body, I have arranged it with the simple or elementary substances. It takes fire at the temperature of 32 (104) of the thermometer.

TABLE _of the Binary Combinations of Charcoal._

_Simple_ _Substances._ _Resulting Compounds._

{ Oxyd of charcoal Unknown.

Oxygen { Carbonic acid Fixed air, chalky acid.

Sulphur Carburet of sulphur } Phosphorus Carburet of phosphorus } Unknown.

Azote Carburet of azote }

{ Carbono-hydrous radical Hydrogen { Fixed and volatile oils

{ Of these only the carburets of Metallic substances Carburets of metals { iron and zinc are known, and { were formerly called Plumbago.

Alkalies and earths Carburet of potash, &c. Unknown.

SECT. X.--_Observations upon Charcoal, and its Combinations with Simple Substances._

As charcoal has not been hitherto decomposed, it must, in the present state of our knowledge, be considered as a simple substance. By modern experiments it appears to exist ready formed in vegetables; and I have already remarked, that, in these, it is combined with hydrogen, sometimes with azote and phosphorus, forming compound radicals, which may be changed into oxyds or acids according to their degree of oxygenation.

To obtain the charcoal contained in vegetable or animal substances, we subject them to the action of fire, at first moderate, and afterwards very strong, on purpose to drive off the last portions of water, which adhere very obstinately to the charcoal. For chemical purposes, this is usually done in retorts of stone-ware or porcellain, into which the wood, or other matter, is introduced, and then placed in a reverberatory furnace, raised gradually to its greatest heat: The heat volatilizes, or changes into gas, all the parts of the body susceptible of combining with caloric into that form, and the charcoal, being more fixed in its nature, remains in the retort combined with a little earth and some fixed salts.

In the business of charring wood, this is done by a less expensive process. The wood is disposed in heaps, and covered with earth, so as to prevent the access of any more air than is absolutely necessary for supporting the fire, which is kept up till all the water and oil is driven off, after which the fire is extinguished by shutting up all the air-holes.

We may a.n.a.lyse charcoal either by combustion in air, or rather in oxygen gas, or by means of nitric acid. In either case we convert it into carbonic acid, and sometimes a little potash and some neutral salts remain. This a.n.a.lysis has. .h.i.therto been but little attended to by chemists; and we are not even certain if potash exists in charcoal before combustion, or whether it be formed by means of some unknown combination during that process.

SECT. XI.--_Observations upon the Muriatic, Fluoric, and Boracic Radicals, and their Combinations._

As the combinations of these substances, either with each other, or with the other combustible bodies, are hitherto entirely unknown, we have not attempted to form any table for their nomenclature. We only know that these radicals are susceptible of oxygenation, and of forming the muriatic, fluoric, and boracic acids, and that in the acid state they enter into a number of combinations, to be afterwards detailed.

Chemistry has. .h.i.therto been unable to disoxygenate any of them, so as to produce them in a simple state. For this purpose, some substance must be employed to which oxygen has a stronger affinity than to their radicals, either by means of single affinity, or by double elective attraction.

All that is known relative to the origin of the radicals of these acids will be mentioned in the sections set apart for considering their combinations with the salifiable bases.

SECT. XII.--_Observations upon the Combinations of Metals with each other._

Before closing our account of the simple or elementary substances, it might be supposed necessary to give a table of alloys or combinations of metals with each other; but, as such a table would be both exceedingly voluminous and very unsatisfactory, without going into a series of experiments not yet attempted, I have thought it adviseable to omit it altogether. All that is necessary to be mentioned is, that these alloys should be named according to the metal in largest proportion in the mixture or combination; thus the term _alloy of gold and silver_, or gold alloyed with silver, indicates that gold is the predominating metal.

Metallic alloys, like all other combinations, have a point of saturation. It would even appear, from the experiments of Mr de la Briche, that they have two perfectly distinct degrees of saturation.

TABLE _of the Combinations of Azote in the state of Nitrous Acid with the Salifiable Bases, arranged according to the affinities of these Bases with the Acid_.

_Names of the bases._ _Names of the neutral salts._ _New nomenclature._ _Notes._

Barytes Nitrite of barytes. { Potash potash. { These salts are only Soda soda. { known of late, and Lime lime. { have received no particular Magnesia magnesia. { name in the old Ammoniac ammoniac. { nomenclature.

Argill argill. {

{ As metals dissolve both in nitrous and Oxyd of zinc zinc. { nitric acids, metallic salts must of iron iron. { consequence be formed having manganese manganese. { different degrees of oxygenation.

cobalt cobalt. { Those wherein the metal is nickel nickel. { least oxygenated must be lead lead. { called Nitrites, when more so, tin tin. { Nitrats; but the limits of this copper copper. { distinction are difficultly bis.m.u.th bis.m.u.th. { ascertainable. The older antimony antimony. { chemists were not acquainted a.r.s.enic a.r.s.enic. { with any of these salts.

mercury mercury. {

silver { It is extremely probable that gold, silver gold { and platina only form nitrats, and cannot subsist platina { in the state of nitrites.

TABLE _of the Combinations of Azote, completely saturated with Oxygen, in the state of Nitric Acid, with the Salifiable Bases, in the order of the affinity with the Acid_.

_Bases._ _Names of the resulting neutral salts._

_New nomenclature._ _Old nomenclature._