Cooley's Cyclopaedia of Practical Receipts Volume I Part 7

3. Acetic acid containing 20% of water may be deprived of a good deal of its superfluous water by standing over dry sulphate of soda. (Liebig.) It may then be used either with or without distillation.

4. Acetic acid, of ordinary strength, may be concentrated to any degree, by rectification once, or oftener, from dry acetate of potash or soda, rejecting the first and last portions. The same acetate may be used repeatedly. The temperature need not exceed 400, and must not rise above 570 Fahr.

ACETIC ACID. (B. P.) _Syn._ ACIDUM ACETIc.u.m. Water mixed with 33% of hydrated acetic acid. Prepared by distilling acetate of soda with sulphuric acid. Colourless sour liquid. Sp. gr. 1044.

_Prop._ Pure hydrated acetic acid is a thin, colourless liquid above 62 Fahr.; at 50 to 55 it crystallises in large, brilliant, colourless, transparent needles and plates, and even at 60 if a crystal of the acid be dropped in; at 40 it is a solid crystalline ma.s.s. Sp. gr.--liquid, 1063 (Mollerat) to 10635 (Mohr);[3]--crystallised, 1135 at 55 Fahr.

(Ure). Odour, intensely pungent when concentrated, but grateful, fragrant, and refreshing, when diffused; taste, intensely sour and acrid, becoming agreeable and refreshing, on sufficient dilution with water; volatile; inflammable, burning with a white flame; vapour of boiling acid highly combustible; dissolves camphor, resins, gum resins, volatile oils, gelatin, gliadin, coagulated alb.u.men, and fibrin (as muscle or the cra.s.samentum of the blood); it coagulates casein, but not liquid alb.u.men (as the serum of the blood and white of egg): miscible with alcohol, ether, and water in all proportions; boils at 248 Fahr.;[4] and is decomposed at a red heat. Its salts are called ACETATES (which _see_).

[Footnote 3: 1064--H. M. Witt (Ure's '_Dict., of Arts, M. & M._,' 5th ed.); 1063 to 1065--Muspratt ('_Chemistry, Theor. & Prac._,' p. 2); 106296--Pereira (4th ed.); 10629--Brande; 1062--Ure; 1057--Berzelius ('_Jahr. ber._,' xvi, 192):--variations evidently arising from difference of purity in the acid examined, or from difference of temperature. The sp.

gr. 1080, with other numbers given by Prof. Lehmann ('_Chemistry_,' Day's Transl.), is probably a misprint.]

[Footnote 4: This is the boiling-point given by the best authorities, and confirmed by Gerhardt ('_Chimie Organique_,' i, 718). Ure made it 230(an error corrected in 5th ed.), Lehmann says 243140, and others give it at 235, 240, &c. An acid of about 80% (sp. gr. 1073 to 10743), its maximum density, boils at 219 to 220 Fahr.]

_Char., Tests, &c._--1. Free acetic acid reddens litmus paper, like the other acids; and may be readily recognised by its odour and volatility:--2. Sesquichloride of iron being added, and the acid then nearly saturated with ammonia, the fluid acquires a deep dark-red colour.

_Estim._ See ACETIMETRY. Organic mixtures that cannot be thus tested, or from which the acid cannot be obtained by simple distillation, may be neutralised, if acid, with carbonate of lime, boiled for a few minutes, cooled, filtered, the lime precipitated with dilute sulphuric acid, and the whole submitted to distillation, when the acid contents of the distillate may be estimated as above.

_Pur._ By heat, it escapes (entirely) in vapour; nothing is precipitated on the addition of either hydrosulphuric acid, nitrate of silver, or chloride of barium. Sometimes it is contaminated with sulphurous acid, which may be recognised by putting a fluid drachm of the acid, mixed with an ounce of distilled water and half a drachm of pure hydrochloric acid, also a few pieces of granulated zinc, into a flask. While effervescence continues suspend a slip of white blotting-paper, moistened with solution of sub-acetate of lead, in the upper part of the flask above the liquid, for about five minutes. The paper should not be discoloured, and thus indicate the absence of sulphurous acid.

_Adult._ The acetic acid of the shops is chiefly adulterated with water.

Sulphurous acid and lead are accidental contaminations; that of the latter often reaches 2%, making the acid poisonous.

_Phys. eff., &c._ In its concentrated state it is a corrosive and an acrid poison. Taken internally, it acts by dissolving the animal tissues, and by thus destroying the organisation causes death, like the other acids. In the dilute form it acts as a stimulant, rubefacient, alterative, refrigerant, and escharotic.

_Uses._ Acetic acid is much employed by the chemist and pharmaceutist, in the manufacture of various preparations, and in a.n.a.lysis; by the perfumer, in the composition of several of his most refreshing and agreeable scents; and in medicine, as an antiseptic, stimulant, rubefacient, alterative, refrigerant, and escharotic. Acetic acid (B. P.) applied by means of a piece of rag tied to the end of a small stick, is a nearly certain cure for ring-worm and scaldhead--one or two applications generally effecting a cure, and the severe smarting it causes is only of short duration; as a caustic, it removes warts and corns; a piece of lint or blotting-paper wetted with it and applied to the skin (evaporation being prevented), forms a useful extemporaneous blister. It was once employed as a disinfectant; but is now only used as a fumigation, to disguise the unpleasant smell of the sickroom and crowded a.s.semblies. It is a popular refreshing scent in faintings, asphyxia, and nervous headache; and is a valuable rubefacient, astringent, and local stimulant. It is also used as a rubefacient and caustic in veterinary practice.

In the _arts_, the commercial acid (pure pyroligneous acid) is used by the engraver to etch his plates; as an antiseptic in pickling and preserving animal and vegetable substances used as food, and anatomical preparations; in dyeing and calico printing, and in the manufacture of medicated vinegars and other pharmaceutical preparations.

In the dilute state, its properties and applications are similar to those of ordinary vinegar, and are noticed under that head.

_Poisoning_ from acetic acid is rare. When concentrated, it is capable, by its corrosive and solvent action, of perforating the coats of the stomach and digestive ca.n.a.l; and it colours the mucus of these organs by the chemical action it exerts upon the blood. Vinegar in an excessive quant.i.ty acts in a similar way, but in a slighter degree. The _treatment_ and _antidotes_ are similar to those directed in cases of poisoning by the other acids. See POISONS.

_Duty, Excise, &c._ See VINEGAR.

_Gen. commentary._ Acetic acid, on the large scale, is princ.i.p.ally prepared from acetate of soda, which yields by a comparatively inexpensive, and not a difficult operation, an acid sufficiently strong and pure for commercial purposes, without the necessity of rectification.

In this process shallow vessels of wood or of copper formed without rivets or solder (except silver solder) in those parts exposed to the action of the acid, are generally employed for the purpose of the distillation. A coil of drawn copper pipe, heated by steam having a pressure of 30 to 40 lbs. to the inch, traverses the bottom of the apparatus, to impart the necessary heat. The refrigerator consists of well-cooled earthenware, Berlin ware, or gla.s.s vessels; and the adopter pipe is also of the same materials. Another common form, which is even still more convenient, is a stout copper still, furnished with a cast-iron jacket to hold high-pressure steam, the usual refrigeratory being employed. In a few instances the s.p.a.ce between the still and jacket is filled with sand, oil, tallow, or fusible metal; in which case the apparatus is set in brickwork, and heated by a naked fire. Stills of earthenware are also frequently employed; and even worms and condensers of silver, or silvered copper, are sometimes used, and with advantage. With a leaden worm the product is always contaminated with a little of that metal; the efforts of the manufacturer to the contrary, by the exclusion of air, and by rejecting the first and last portions of the distillate, only lessening and not preventing this evil. A lute (if any) composed of linseed meal and water, with or without a little powdered plaster of paris, may be employed; but flat bands and short tubes of well-seasoned vulcanised india rubber are infinitely more convenient and efficacious. The ingredients being placed in the still, and well but hastily stirred together with a wooden spatula, the head is luted on, and the distillation soon afterwards commenced. The chief care now should be to increase the heat gradually as the distillation proceeds; and when a steam-heat is not used, to carefully avoid over-firing, particularly towards the close of the operation. A little acetic ether is added by some manufacturers. In this way 4 lbs. of acid of the sp. gr. 1050, is obtained for every 3 lbs. of acetate of soda employed. Should rectification be had recourse to, the addition of about 2 or 3% of bichromate of potash, peroxide of manganese, or red oxide of lead, will remove empyreuma, if present. The first of these substances is the most effective; the power of the others being in the order in which they are printed. In distilling the weaker acids and vinegars, it is found useful to add from 25 to 30% of chloride of sodium, which, by raising the boiling-point of the liquid, allows the acid the more freely to pa.s.s over (Stein); but this addition proves disadvantageous when any sulphuric acid is present, in which case sulphate of soda may be employed instead. If this addition be not made, the whole of the acid cannot be obtained without distillation to dryness, and the generation of empyreuma.

On the small scale, gla.s.s retorts are usually directed to be used, but gla.s.s alembics or flasks are more convenient and safe, as already noticed.

In the preparation of the pure acid, care should be taken that the acetate of soda does not contain common salt, as the carbonate of soda prepared by calcination, and frequently used to form the acetate, is generally contaminated with it, and yields up its hydrochloric acid or chlorine during the process of distillation, thus vitiating the product. In all the methods given the product becomes more concentrated in proportion to the dryness of the acetate and the strength of the oil of vitriol or muriatic acid employed. By using the one dry, and the other concentrated, glacial acid may always be obtained by collecting separately the last two fifths that come over, and submitting this to refrigeration.

According to Melsens, pure GLACIAL ACETIC ACID is most advantageously obtained by distilling pure and dry acetate of potash with an excess of strong and moderately pure acetic acid, rejecting that which first pa.s.ses over.

Acetate of soda may be safely dried at a temperature of 400 to 450, provided care be taken to avoid ignition from contact with sparks. A less heat is, however, quite sufficient to drive off the whole of its water of crystallisation. It is known to be dry by its a.s.suming the appearance of a smooth oily liquid whilst hot. If, whilst heated, it emits fumes, it is suffering decomposition. The same applies to the other commercial acetates. Crystallised acetate of soda loses about 2/5ths of its weight by thorough drying.

When acetate of soda and sulphuric acid are the ingredients employed in the production of acetic acid, sulphate of soda is formed, which, in the large way, the chemist returns to the manufacturer of acetate of soda (_i.

e._ to the pyroligneous acid maker), who employs it in the decomposition of fresh acetate or pyrolignite of lime. In this way the same soda-salt is employed over and over again, acting merely as the vehicle for the separation of the crude acetic acid in the solid form, and its easy and cheap transportation from one point to another. This ingenious method of mutual a.s.sistance resulting from the application of chemical science to provide for the wants of everyday life, offers some explanation of the extraordinarily low price at which acetic acid may now be purchased.

The acetic acid of commerce (pure pyroligneous acid) is almost wholly obtained from the acetates of soda and lime. The princ.i.p.al supply of crude acetate (pyrolignite) of soda is from America, Norway, and Sweden; but much is also obtained from our home manufactories. See ACETIFICATION, ACETIMETRY, FERMENTATION, PYROLIGNEOUS ACID, SODIUM, (Acetate of), VINEGAR, &c.

More recently, acetic acid has been obtained by decomposing with hydrochloric acid the double salt of chloride of calcium and acetate of lime, mentioned by Fritzsche ('Ann. de Poggend,' xxviii, 123). For this purpose, solutions of acetate of lime and chloride of calcium are mixed and evaporated, the combined salts readily crystallising in large needles.

These are freed from the mother-liquor and distilled with common muriatic acid.

The acid furnished by this method requires redistillation, and is, moreover, contaminated with some of the fatty products always present in the crude pyrolignite.

=Anhydrous Acetic Acid.= _Syn._ ACETIC ANHYDRIDE. Acetic acid deprived of the elements of water.

Acetic Acid. Water. Acetic Anhydride.

2C_{2}H_{4}O_{2} - H_{2}O = C_{4}H_{6}O_{3}.

=Aromat'ic Acetic Acid.= _Syn._ AROMATIC VINEGAR; A. SPIRIT OF V.; ACIDUM ACE'TIc.u.m AROMAT'Ic.u.m, L.--_Prep._ 1. (Ph. E. 1839.) Dried rosemary and origanum, of each 1 oz.; lavender flowers, 1/2 oz.; bruised cloves, 1/2 dr.; acetic acid (sp. gr. 1068), 1-1/2 pint; macerate for 7 days, express, and filter. A fragrant and refreshing perfume. Omitted in Ph. E.

1841 and P. B. 1867.

2. (Ph. E. 1817.) As the last, but using distilled vinegar instead of the strong acid of the Pharmacopia. Inferior.

3. (P. Cod. 1839) Camphor, 2 oz.; oil of lavender, 10 gr.; oil of cinnamon, 20 gr.; oil of cloves, 30 gr.; concentrated acetic acid, 1 pint.

Very fragrant and refreshing.

4. (Ph. Bor. 1847; Cod. Med. Hamb. 1845.) Oil of cloves, 1 dr.; oils of lavender and citron, of each 2 scrup.; oils of bergamot and thyme, of each 1 scrup.; oil of cinnamon, 10 drops; strongest acetic acid, 1 oz.; mix.

Limpid; yellow-brown; highly fragrant and refreshing. See ACETIC ACID (Camphorated), and VINEGAR (Aromatic).

=Beaufoy's Acetic Acid.= A superior commercial acetic acid (_i. e._ purified pyroligneous acid), having a sp. gr. of about 1044; or containing about 28% of real acetic acid, or 32 to 33% of the hydrated acid. Same strength, &c., as ACETIC ACID P. B.

=Cam'phorated Acetic Acid.= _Syn._ CAMPHORATED VINEGAR; ACIDUM ACE'TIc.u.m CAMPHORA'TUM, L.--_Prep._ 1. (Ph. E. 1841.) Camphor, 1/2 oz.; pulverise it by means of a few drops of spirit of wine, and then dissolve it in acetic acid (Ph. E.), 6-1/2 fl. oz.

2. (Ph. D. 1850.) Camphor, 1 oz.; rectified spirit, 1 fl. dr.; pulverise, and dissolve in strong acetic acid (acid. acet. fort. Ph. D.), 10 fl. oz.

_Obs._ This preparation is intended as a subst.i.tute for the aromatic acetic acid of the shops and previous pharmacopias. It is also useful as an embrocation, in rheumatism and neuralgia; as an extemporaneous vesicant and counter-irritant; and as a fumigation in fevers, &c.

=Dilute' Acetic Acid.= _Syn._ ACIDUM ACETIc.u.m DILU'TUM, L. Acetic acid, 1 pint; distilled water, 7 pints; mix, Sp. gr. 1006. One fluid ounce corresponds to 16 grains of anhydrous acid (363 per cent.).

=Glacial Acetic Acid.= _Syn._ ACIDUM ACETIc.u.m GLACIALE. Acetate of soda, 20 oz., is liquefied by a gentle heat, stirred till it becomes pulverulent, and then further heated until it fuses; it is at once removed from the fire, and, when cool, the ma.s.s is broken up, placed in a 3-pint stoppered retort connected with a Liebig's condenser, and then treated with sulphuric acid, 8 fl. oz. When the distillation slackens heat is to be applied, and the process continued until 6 fl. oz. of acetic acid have pa.s.sed over. If a little of the product strikes a blue colour when mixed with a solution of iodate of pota.s.sium containing mucilage of starch, the whole product must be agitated with perfectly dry black oxide of manganese, 1/4 oz., and redistilled. Sp. gr. 1065; contains 85% of anhydrous acid.

=ACETIC ANHYDRIDE.= See ANHYDROUS ACETIC ACID.

=ACETICA.= [L.] Medicated vinegars.

=ACETIDUX, Dr DELFER'S.= Made by Dollinger, of Berlin. For the radical and painless removal of warts, corns, hard skin, &c. A solution of 5 grms. of chromic acid in 15 grms. of water. (Schadler.)

=ACETIFICATION.= _Syn._ ACETIFACIO, L.; ACETIFICATION, Fr.; ESSIGMACHEN, EINSAuERN, Ger. In _chemistry_, the act or process of converting into vinegar; also the state of undergoing such conversion.

Acetic acid is produced either by the partial dehydrogenation and subsequent oxidation of bodies containing its elements, or by their destructive distillation. The first is effected--by their exposure, in a finely divided state, to the action of air or atmospheric oxygen, as in the quick process of making vinegar; or--by submitting them, in combination with ferments, to contact with a free supply of atmospheric air, as in the old field process of making vinegar; or--by exposure to the direct action of chemical or mechanical oxidizing agents, as condensed air (platinum-black process), chromic and nitric acid, &c. In general, it is alcohol more or less dilute, particularly as it exists in fermented liquors, which is thus converted into acetic acid. In the second process (destructive distillation), wood is the substance usually employed, and heat is the agent which develops the acid.

The conversion of alcohol into acetic acid is not immediate and direct.

The atmospheric oxygen first oxidises two atoms of its hydrogen, aldehyd and water being formed; and this aldehyd uniting with one atom of oxygen produces one molecule of ACETIC ACID. The changes are represented in the following equations:--

Alcohol. Oxygen. Aldehyd. Water.

=1.= C_{2}H_{6}O + O = C_{2}H_{4}O + H_{2}O