Elements of Chemistry Part 21

TABLE _of the Combinations of Pyro-mucous Acid, with the Salifiable Bases, in the Order of Affinity(A)._

_Bases._ _Neutral Salts._

Potash Pyro-mucite of potash.

Soda soda.

Barytes barytes.

Lime lime.

Magnesia magnesia.

Ammoniac ammoniac.

Argill argill.

Oxyd of zinc zinc.

manganese manganese.

iron iron.

lead lead.

tin tin.

cobalt cobalt.

copper copper.

nickel nickel.

a.r.s.enic a.r.s.enic.

bis.m.u.th bis.m.u.th.

antimony antimony.

[Note A: All these combinations were unknown to the ancient chemists.--A.]

SECT. x.x.xI.--_Observations upon Pyro-mucous Acid, and its Combinations._

This acid is obtained by distillation in a naked fire from sugar, and all the saccharine bodies; and, as these substances swell greatly in the fire, it is necessary to leave seven-eighths of the retort empty. It is of a yellow colour, verging to red, and leaves a mark upon the skin, which will not remove but alongst with the epidermis. It may be procured less coloured, by means of a second distillation, and is concentrated by freezing, as is directed for the citric acid. It is chiefly composed of water and oil slightly oxygenated, and is convertible into oxalic and malic acids by farther oxygenation with the nitric acid.

It has been pretended that a large quant.i.ty of gas is disengaged during the distillation of this acid, which is not the case if it be conducted slowly, by means of moderate heat.

TABLE _of the Combinations of the Oxalic Acid, with the Salifiable Bases, in the Order of Affinity(A)._

_Bases._ _Neutral Salts._

Lime Oxalat of lime.

Barytes barytes.

Magnesia magnesia.

Potash potash.

Soda soda.

Ammoniac ammoniac.

Argill argill.

Oxyd of zinc zinc.

iron iron.

manganese manganese.

cobalt cobalt.

nickel nickel.

lead lead.

copper copper.

bis.m.u.th bis.m.u.th.

antimony antimony.

a.r.s.enic a.r.s.enic.

mercury mercury.

silver silver.

gold gold.

platina platina.

[Note A: All unknown to the ancient chemists.--A.]

SECT. x.x.xII.--_Observations upon Oxalic Acid, and its Combinations._

The oxalic acid is mostly prepared in Switzerland and Germany from the expressed juice of sorrel, from which it cristallizes by being left long at rest; in this state it is partly saturated with potash, forming a true acidulous oxalat of potash, or salt with excess of acid. To obtain it pure, it must be formed artificially by oxygenating sugar, which seems to be the true oxalic radical. Upon one part of sugar pour six or eight parts of nitric acid, and apply a gentle heat; a considerable effervescence takes place, and a great quant.i.ty of nitrous gas is disengaged; the nitric acid is decomposed, and its oxygen unites to the sugar: By allowing the liquor to stand at rest, cristals of pure oxalic acid are formed, which must be dried upon blotting paper, to separate any remaining portions of nitric acid; and, to ensure the purity of the acid, dissolve the cristals in distilled water, and cristallize them afresh.

+---------------+------------------+--------------------------------------- | _Bases._ | _Neutral salts._ |_Names of the resulting neutral salts_ | | | |_according to the old nomenclature._ | |---------------+------------------+---------------------------------------+ |Barytes |Acet.i.te of barytes{Unknown to the ancients. Discovered by | | | {Mr de Morveau, who calls it _barotic | | | {acete_. | | | | | |Potash | ---- potash {Secret terra foliata tartari of Muller.| | | {Arcanum tartari of Basil Valentin and | | | {Paracelsus. Purgative magistery of | | | {tartar of Schroeder. Essential salt of | | | {wine of Zwelfer. Regenerated tartar of | | | {Tachenius. Diuretic salt of Sylvius | | | {and Wilson. | | | | | |Soda | ---- soda {Foliated earth with base of mineral | | | {alkali. Mineral or crystallisable | | | {foliated earth. Mineral acetous salt. | | | | | |Lime | ---- lime {Salt of chalk, coral, or crabs eyes; | | | {mentioned by Hartman. | | | | | |Magnesia | ---- magnesia |First mentioned by Mr Wenzel. | | | | | |Ammoniac | ---- ammoniac {Spiritus Mindereri. | | | {Ammoniacal acetous salt. | | | | | |Oxyd of zinc | ---- zinc {Known to Glauber, Schwedemberg, | | | {Respour, Pott, de La.s.sone, and Wenzel, | | | {but not named. | | | | | | ---- manganese| ---- manganese |Unknown to the ancients. | | | | | | ---- iron | ---- iron {Martial vinegar. Described by Monnet, | | | {Wenzel, and the Duke d'Ayen. | | | | | | ---- lead | ---- lead {Sugar, vinegar, and salt of lead or | | | {Saturn. | | | | | | ---- tin | ---- tin {Known to Lemery, Margraff, Monnet, | | | {Weslendorf, and Wenzel, but not named. | | | | | | ---- cobalt | ---- cobalt |Sympathetic ink of Mr Cadet. | | | | | | ---- copper | ---- copper {Verdigris, crystals of verditer, | | | {verditer, distilled verdigris, crystals| | | {of Venus or of copper. | | | | | | ---- nickel | ---- nickel |Unknown to the ancients. | | | | | | ---- a.r.s.enic | ---- a.r.s.enic {a.r.s.enico-acetous fuming liquor, | | | {liquid phosphorus of Mr Cadet. | | | | | | ---- bis.m.u.th | ---- bis.m.u.th {Sugar of bis.m.u.th of Mr Geoffroi. Known | | | {to Gellert, Pott, Weslendorf, Bergman, | | | {and de Morveau. | | | | | | ---- mercury | ---- mercury {Mercurial foliated earth, Keyser's | | | {famous antivenereal remedy. Mentioned | | | {by Gebaver in 1748; known to Helot, | | | {Margraff, Baume, Bergman, and | | | {de Morveau. | | | | | | ---- antimony | ---- antimony |Unknown. | | | | | | ---- silver | ---- silver {Described by Margraff, Monnet, and | | | {Wenzel; unknown to the ancients. | | | | | | ---- gold | ---- gold {Little known, mentioned by Schroeder | | | {and Juncker. | | | | | | ---- platina | ---- platina |Unknown. | | | | | |Argill | ---- argill |According to Mr Wenzel, vinegar | | | |dissolves only a very small proportion | | | |of argill. | +---------------+------------------+---------------------------------------+

From the liquor remaining after the first cristallization of the oxalic acid we may obtain malic acid by refrigeration: This acid is more oxygenated than the oxalic; and, by a further oxygenation, the sugar is convertible into acetous acid, or vinegar.

The oxalic acid, combined with a small quant.i.ty of soda or potash, has the property, like the tartarous acid, of entering into a number of combinations without suffering decomposition: These combinations form triple salts, or neutral salts with double bases, which ought to have proper names. The salt of sorrel, which is potash having oxalic acid combined in excess, is named acidulous oxalat of potash in our new nomenclature.

The acid procured from sorrel has been known to chemists for more than a century, being mentioned by Mr Duclos in the Memoirs of the Academy for 1688, and was pretty accurately described by Boerhaave; but Mr Scheele first showed that it contained potash, and demonstrated its ident.i.ty with the acid formed by the oxygenation of sugar.

SECT. x.x.xIII.--_Observations upon Acetous Acid, and its Combinations._

This acid is composed of charcoal and hydrogen united together, and brought to the state of an acid by the addition of oxygen; it is consequently formed by the same elements with the tartarous oxalic, citric, malic acids, and others, but the elements exist in different proportions in each of these; and it would appear that the acetous acid is in a higher state of oxygenation than these other acids. I have some reason to believe that the acetous radical contains a small portion of azote; and, as this element is not contained in the radicals of any vegetable acid except the tartarous, this circ.u.mstance is one of the causes of difference. The acetous acid, or vinegar, is produced by exposing wine to a gentle heat, with the addition of some ferment: This is usually the ley, or mother, which has separated from other vinegar during fermentation, or some similar matter. The spiritous part of the wine, which consists of charcoal and hydrogen, is oxygenated, and converted into vinegar: This operation can only take place with free access of air, and is always attended by a diminution of the air employed in consequence of the absorption of oxygen; wherefore, it ought always to be carried on in vessels only half filled with the vinous liquor submitted to the acetous fermentation. The acid formed during this process is very volatile, is mixed with a large proportion of water, and with many foreign substances; and, to obtain it pure, it is distilled in stone or gla.s.s vessels by a gentle fire. The acid which pa.s.ses over in distillation is somewhat changed by the process, and is not exactly of the same nature with what remains in the alembic, but seems less oxygenated: This circ.u.mstance has not been formerly observed by chemists.

Distillation is not sufficient for depriving this acid of all its unnecessary water; and, for this purpose, the best way is by exposing it to a degree of cold from 4 to 6 below the freezing point, from 19 to 23 of Fahrenheit; by this means the aqueous part becomes frozen, and leaves the acid in a liquid state, and considerably concentrated. In the usual temperature of the air, this acid can only exist in the ga.s.seous form, and can only be retained by combination with a large proportion of water. There are other chemical processes for obtaining the acetous acid, which consist in oxygenating the tartarous, oxalic, or malic acids, by means of nitric acid; but there is reason to believe the proportions of the elements of the radical are changed during this process. Mr Ha.s.senfratz is at present engaged in repeating the experiments by which these conversions are said to be produced.

The combinations of acetous acid with the various salifiable bases are very readily formed; but most of the resulting neutral salts are not cristallizable, whereas those produced by the tartarous and oxalic acids are, in general, hardly soluble. Tartarite and oxalat of lime are not soluble in any sensible degree: The malats are a medium between the oxalats and acet.i.tes, with respect to solubility, and the malic acid is in the middle degree of saturation between the oxalic and acetous acids.

With this, as with all the acids, the metals require to be oxydated previous to solution.

The ancient chemists knew hardly any of the salts formed by the combinations of acetous acid with the salifiable bases, except the acet.i.tes of potash, soda, ammoniac, copper, and lead. Mr Cadet discovered the acet.i.te of a.r.s.enic[47]; Mr Wenzel, the Dijon academicians Mr de La.s.sone, and Mr Proust, made us acquainted with the properties of the other acet.i.tes. From the property which acet.i.te of potash possesses, of giving out ammoniac in distillation, there is some reason to suppose, that, besides charcoal and hydrogen, the acetous radical contains a small proportion of azote, though it is not impossible but the above production of ammoniac may be occasioned by the decomposition of the potash.

TABLE _of the Combinations of Acetic Acid with the Salifiable Bases, in the order of affinity._

_Bases._ _Neutral Salts._

Barytes Acetat of barytes.

Potash potash.

Soda soda.

Lime lime.

Magnesia magnesia.

Ammoniac ammoniac.

Oxyd of zinc zinc.

manganese manganese.