Although from these facts it would appear there is an insuperable barrier to the prolonged occupation of tropical countries by white races, yet much may be done by attention to the laws of health and disease. One cause of the great amount of mortality amongst Europeans in the tropics is that they continue the habits they had acquired in cold countries when they arrive in the hotter parts of the world. An attention to diet, clothing, and residence, would do much to remove many of the causes of disease. It would appear also that many of the races that now inhabit cold climates made their way from warmer countries, and that changes gradually produced in the constitution, as by the slow advance of peoples north or south, may overcome that tendency to succumb which is so evident in the rapid removals to which the above data refer. The question of the permanent occupation of tropical countries has become one of vital importance to the two great European governments of England and France. How this can be done at the least expense of human life can only be ascertained by the study of the laws which regulate acclimation.

ACCOLADE. This French word, derived from the Latin ad, to, and collum, the neck, signifies, in familiar speech, an embrace; and this idea, or that of union by means of the neck, as when two oxen are yoked together, is that which prevails in various other derivatives from the same root, both in the French and Italian languages. Some, accordingly, have supposed that, when used as descriptive of a certain part of the ancient ceremony of conferring knighthood, the particular act which it denoted was the embrace, accompanied with a kiss, which was bestowed upon the new-made knight, in token of the brotherhood established between them by his admission into the order of chivalry. It has, however, been the more generally-received opinion, that the accolade was what we call in English (though perhaps improperly) the dubbing, the slight blow given to the cheek or shoulder of the knight, as an emblem," to use the language of Gibbon," of the last affront which it was lawful for him to endure." There is no doubt as to the great antiquity of this last-mentioned custom. Gregory of Tours, writing in the 6th century, describes the blow on the shoulder as part of the ceremony with which the kings of France, of the first race, were wont to confer the honour of knighthood. It has been derived, by some antiquaries, from the blow which the Roman slave received from his master when manumitted, or made a freeman. The blow of liberation, indeed, whatever may have been its original import, may be traced in various directions among the usages of the middle ages. The blow by which knighthood was conferred seems to have been originally given with the hand, for which the flat part of the sword was afterwards substituted.

ACCOMPANIMENT, in Music, is the subordinate part, or parts, accompanying a voice, or several voices, or a principal instrument, &c. The piano-forte or guitar part of a song is the accompaniment, the air itself being the principal, the other only the useful ally, the support. In a concerto the whole band accompany the instrument for which the chief and prominent part is composed.

Accompaniment is also the harmony of a figured base, or another word for what is, by a foolish, unmeaning term-but too generally adopted to be at once discarded-called thorough-base.

The Accompaniment of the Scale is the harmony assigned, partly by what may be called nature and partly by custom, to that series of notes denominated the diatonic scale ascending and descending, such scale being taken as a base. For an explanation of these matters, see THOROUGH-BASE. See also DIATONIC; SCALE.

Dr. Burney (in Rees' Cyclopædia') seems inclined to favour the opinion of Rousseau, that an accompaniment of the smallest possible number of notes is to be preferred. Rousseau had not acquired a taste for rich harmony, for with the music of the German school he was very little, if at all, acquainted; but that Burney should have sanctioned opinions formed upon the imperfect knowledge of the subject existing in the middle of the last century, is somewhat a matter of surprise. A judicious medium, in this as in other things, is the best. The old Italian accompaniment can now hardly be endured; while, certainly, many ultra-Germanists of the present day overpower melody by the multitude of notes which they are so prone to employ. ACCOMPLICE. [APPROVER.] ACCOMPTS. [BOOKKEEPING.] ACCORDION. A musical instrument which came into England, from Germany, about the year 1828.

The Accordion is in the form of a small oblong box, varying from eight to twenty inches in length. The interior exhibits a row of very small elastic metallic lamina, or springs, fixed at one end in a plate of metal, so that they may vibrate freely. The upper and lower parts of the box are united by a folding apparatus or bellows, which supplies the air required to put the springs into vibration, and to these the air is

admitted by means of valves acted on by keys, in the manner of an organ. There is also a very simple contrivance by which a base note or drone may be added, at the discretion of the performer. These instruments vary in size and in capabilities: the compass of the most complete is from & the fourth space in the base staff, to E the seventh additional space above the treble, including all the semitones. Hence the accordion is not limited to melody, but can produce the most agreeable harmonic effects.

The principle on which the accordion, and all other instruments of the kind, is founded, is fully explained by Dr. Gottfried Weber, in his 'Leges Oscillationis,' &c., published in 1827, who refers, as his source of information, to an article by Strohmann, in the Allgemeine Musicalische Zeitung' of 1813. This principle, however, had been fully set forth many years before by Professor Robison, in the Encyclopædia Britannica,' under the term 'Musical Trumpet;' and it is now known that the Chinese were familiar with it before its introduction into Europe.

The firms of Reinisch and Steinkeller, at Vienna, sent large collections of beautiful accordions to the Great Exhibition of 1851; as did also Wagner of Reuss, and Zimmerman of Carlsfeld. The 40-keyed accordions of the last-named firm were priced as low as six Prussian thalers (178. 6d.). Small and roughly-made German accordions are now sold in England at extremely low prices. In the commoner instruments, each key is made to elicit two different tones, according as the wind is made to pass into or out of it; but, in some of the better kinds, there are as many keys as notes.

The gentle tones of this beautiful instrument are found to be so attractive to the inhabitants of rude nations, that Roman Catholic missionaries have lately, in some instances, adopted the plan of taking accordions out with them. In musical capability, however, the accordion is far inferior to an instrument of later introduction. [CONCERTINA.] The Flutina is a form of the accordion in which, by a mode of partitioning the interior cavity into cells, a peculiar flute-like quality is given to the tones.

The Organ-accordion, a recent invention, has a row of black and white keys like those of the organ or pianoforte, giving all the tones and semi-tones for three octaves. These keys are played with the fingers of the right-hand, the left-hand being needed to work the bellows. The instrument, too large to be held in the hand, is rested either on a table or on the lap of the performer. It is intended chiefly as an accompaniment to the voice.

Mr. Faulkner has invented an accordion-stand. It is an apparatus to assist in playing the instrument; it will incline to any position suitable to the convenience of the performer; and, by the action of a springtop, it can be fixed in the position chosen.

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ACCOUNT, or ACCOMPT, from the low Latin, computus, is a form of action, and of which frequent mention is made in the old law books. Strictly, it lay only against a bailiff or receiver, requiring him to render an account of the moneys received by him as such; but the form of action being found to be one of the most convenient at that time, it was extended to cases where the person called upon to account was neither a bailiff nor an authorised receiver, if he had in any way received and retained money which it was his duty to have handed over to the claimant. At present, this is effected in many cases by the action for 'money received to the use" of the plaintiff. The action of account is now rarely used, a suit in chancery being generally resorted to. (Blackstone's Comm., Mr. Kerr's ed., vol. iii. pp. 171, 172.) ACCOUNT STATED. This is the title of the common count in the declaration in an action, where the plaintiff seeks to recover the amount due upon a balanced account between the parties. The form states the defendant to be indebted to the plaintiff in a certain sum of money found to be due from the defendant to the plaintiff upon accounts then stated" between them, from which statement of accounts the law implies a promise by the debtor to pay the sum he then admits himself to owe. This form is generally introduced in actions upon simple contracts for the recovery of pecuniary demands. It is not essential that there should be cross or reciprocal demands between the parties, or that the account should relate to more than a single debt or transaction; nor need the original demand be one recoverable at law. Thus, a member of a partnership, though he cannot in general sue his partner at law for his share of the profits, may do so after a balance has been struck in his favour. But it is necessary that there should have existed some claim against the defendant, or some previous transactions in respect of which the account is stated, for an action cannot be brought in this form upon a mere agreement to pay a sum of money, the maxim being ex nudo pacto non oritur actio. It is, therefore, usual in support of this count to give evidence of an original demand or a prior transaction, and of a balance struck and agreed upon, but it is sufficient in the first instance, to prove an admission by the defendant to the plaintiff or his agent, that a certain sum was then due, without showing the origin or nature of the claim, or proving the specific items constituting the account. Thus an I. O. U., a bill, or a promissory note, is primâ facie evidence of an account stated betwixt the immediate parties. The account must have been stated before the action is brought; and the admission, in order to charge a defendant, must be positive, unqualified, and unconditional, and must not be merely the admission of a debt, but either expressly or by reference, the admission of a specific sum being

due. If the plaintiff sues in a representative character, as in that of executor or assignee, he must show that the admission was made to him in that character. The statement of an account is not conclusive but only presumptive evidence against the party who admits the balance to be against him, and does not preclude him from showing, by evidence, the existence of error in the account; unless in the case of an account actually settled by payment, which cannot be opened except upon proof of fraud.

An account stated is also a good plea in bar to a bill in equity for an account. As a party may in equity open up a settled account on the ground of error, in order to support such a plea, the statement of account must be shown to have been final, and in writing. It is not essential that it should have been signed, and it will be sufficient if the account has been acquiesced in for a length of time, affording legal presumption of a settlement. A general release may thus be pleaded as a stated account, and a plea of this kind must aver that the account is just and fair, whether error or fraud is charged by the bill of the plaintiff or not. In answer to a plea of a stated account the plaintiff in equity may show either the existence of fraud, which will be sufficient ground for opening the whole account, or that the account contains specific errors, which will enable him to surcharge, that is, to show omissions for which there ought to be credit, and falsify, that is, to show that there are wrong charges which ought to be deducted. ACCOUNTANT, a person who professes skill in mercantile accounts. In a commercial community occasions are constantly arising for the employment of accountants. They are generally appointed to examine the books of traders who have been compelled by embarrassment in their affairs to summon a meeting of their creditors; or they may be called in by a trader to investigate his accounts, and to ascertain the state of his affairs. The collection of debts or rents, and the windingup of the affairs of persons deceased, or who have given up business, are matters often put into their hands. An accountant has no legal status, like a notary or an auctioneer or appraiser, who perform certain duties which only they are allowed to discharge; but by the statute establishing District Courts of Bankruptcy, 5 & 6 Vict., c. 122, official assignees must be selected from persons in trade, or who are or have been "merchants, brokers, or accountants."

ACCOUNTANT IN BANKRUPTCY, an officer appointed by the Lord Chancellor (5 & 6 Will. IV. c. 29), who has the control, care, and management of the funds belonging to bankrupt estates. He must make an annual return to Parliament (13 & 14 Vict. c. 106, ss. 31, 36, 47, 191). ACCOUNTANT-GENERAL, an officer of the Court of Chancery, first appointed under an Act (12 Geo. I. c. 32) "for securing the moneys and effects of the suitors." The Act recites that ill consequence and great prejudice already had, and might again, ensue to the suitors by having their moneys left in the sole power of the Masters of the Court. The bonds, tallies, orders, and effects of suitors were, it appears, until the passing of this Act, locked up in several chests in the Bank of England, under the direction of the Masters and two of the Six Clerks. The Act confirms a previous order of the Court of Chancery for adopting a different system, and sect. 3 enacts that, "to the end the account between the suitors of the High Court of Chancery and the Bank of England may be the more regularly and plainly kept, and the state of such account may be at all times seen and known," there shall be "one person appointed by the High Court of Chancery to act, perform, and do all such matters and things relating to the delivering of the suitors' money and effects into the Bank, and taking them out of the Bank, &c., which was formerly done by the Masters and Usher of the Court." The Accountant-General is "not to meddle with the suitors' money, but only to keep an account with the Bank." He attends several times a-week at the Bank and other places for the purpose of making sales, transfers, and acceptances of stock, according to the orders of the Court. The Bank receives moneys under a power of attorney from the Accountant-General. (As to the practice in the transfer of stock by and to the Accountant-General, see Daniell's 'Practice in Chancery,' 3rd edit. vol. ii. p. 1306, et seq.) His duties are in some respects regulated by the orders issued by the Court of Chancery. The salary is 3000l. a-year (under 15 & 16 Vict. c. 87, s. 22).

Before the passing of the Act 5 Vict. c. 5, which suppressed the equity jurisdiction of the Court of Exchequer, there was an AccountantGeneral of that court. The duties of the Accountant-General and Masters of the Exchequer are now performed by the Queen's Remembrancer.

There is an Accountant-General of the Irish Court of Chancery. ACCUMULATION. [CAPITAL.] ACCUMULATION. Before the passing of the statute 40 Geo. III. c. 98, a person might suspend the enjoyment of real or personal estate, and direct that the whole profits, rents, and produce thereof should be accumulated for a period not exceeding in extent that of any life or number of lives in being, and 21 years afterwards. The mischievous extent to which an individual at the close of the last century availed himself of this power of directing an accumulation, gave rise to the above statute, the object of which is to prevent the recurrence of a disposition of property so impolitic and unnatural.

The person in question was named Peter Thellusson. He was the son of Isaac de Thellusson, ambassador from Geneva to the court of

Louis XV. He fixed his residence in London about the middle of the 18th century, and accumulated an immense fortune as a merchant. He died on the 21st of July, 1797. His name is now only remembered in connection with his extraordinary will, which led to the restraints upon testamentary dispositions above mentioned.

The property which was the subject of his will consisted of a landed estate of about 4000l. a-year, and of personal property to the amount of about 600,000l. This property he devised and bequeathed to trustees upon trust for accumulation and investment in the purchase of lands during the lives of his sons, grandsons, and the issue of sons and grandsons living, or in ventre sa mere, at the time of his death, and the lives of the survivors and survivor of them; and after that period, to be conveyed to the lineal descendants of his sons in tail male. It had been long understood to be the rule of law that the absolute ownership of property might be suspended, and consequently the property rendered inalienable during lives in being at the time of the creation of the trust; that is, where the trust is created by will, at the time of the death of the testator. This period was afterwards extended so as to allow for the cases of infancy, and of a child in ventre sa mere; but it was for some time questioned whether a term of 21 years might in all cases be added to the period of suspension, though it has since been determined that it may. [SETTLEMENT.] Restraint on the accumulation of income was unknown to the common law, except in so far as the rule against perpetuities necessarily prevented accumulation from being carried beyond its limits; and Mr. Thellusson's will, by confining the restriction to existing lives, escaped the question which then existed as to the allowance of an absolute term of 21 years in addition to a life or lives in being at the time of the creation of the trust.

This will, which, in the events that happened, had the effect of postponing the usufructuary enjoyment of the bulk of the estate till the expiration of nine lives in being at the time of the testator's death, was, after many hard struggles, occasioned rather by the immense value of the property implicated (which it was computed would have amounted, with the expected accumulations, to upwards of 18,000,000l.), than by any new difficulty in the principle, finally established by the decision of the House of Lords on the 25th of June 1805. (Thellusson v. Woodford, 11 Ves. 112.)

The case of Thellusson v. Woodford gave rise to the Act of the 40 Geo. III. c. 98, "for restraining all trusts and directions in deeds or wills whereby the profits or produce of real or personal estates shall be accumulated and the beneficial enjoyment thereof postponed beyond the term therein limited." By the provisions of this Act, no person can settle or dispose of property by deed, will, or otherwise, so as to accumulate the income thereof, either wholly or partially, "for any longer term than the life or lives of any such grantor or grantors, settlor or settlors, or the term of twenty-one years from the death of any such grantor, settlor, devisor, or testator, or during the minority or respective minorities of any person or persons who shall be living or in ventre sa mere, at the time of the death of such grantor, devisor, or testator, or during the minority or respective minorities only of any person or persons who, under the uses or trusts of the deed, surrender, will, or other assurances directing such accumulations, would for the time being, if of full age, be entitled to the rents, issues, and profits, or the interest, dividends, and annual produce so directed to be accumulated. And in every case where accumulation shall be directed otherwise than as aforesaid, such direction shall be null and void, and the rents, issues, profits, and produce of such property so directed to be accumulated shall, so long as the same shall be directed to be accumulated contrary to the provisions of this Act, go to and be received by such person or persons as would have been entitled thereto, if such accumulation had not been directed."

It is now settled upon this statute, that a trust for accumulation reaching beyond the allowed period is good for the period allowed by law, and void only for the excess. (12 Ves. 295; 4 Russ. 403.)

ACCUMULATION OF POWER is a term applied to that quantity of motion which exists in some machines at the end of intervals of time, during which the velocity of the moving body has been constantly accelerated.

The simplest case in which there is such an accumulation of power is that of a heavy body, like the rammer of a pile-driving machine, which descends by the action of gravity during a certain time and impinges upon some object. At the moment of impact, supposing that the object struck does not move, the velocities of all the particles which had gone on continually increasing during the descent, are destroyed, and thus a shock is produced immensely greater than that which would result from the mere pressure of the body. The batteringram of the ancients when, being suspended from some fixed point it was allowed to swing by the action of gravity till one of its extremities struck the face of a wall, produced its effect in like manner by the power accumulated in it during its motion. In all such cases, the effect, if measured by the magnitude of an impression or indentation produced in the object struck, is, by Mechanics, directly proportional to the mass in motion, and to the square of the velocity at the instant of impact.

The accumulation produced by the continuous action of gravity, when a body has not far to fall, is commonly increased by that of a

ACETIC ACID constitutes the sour element of vinegar, and from it the latter derives its peculiar and valuable properties; vinegar in fact, in whatever way made, is dilute acetic acid, mixed generally with colouring matter, and some slight impurities.

Acetic acid exists in the juice of some plants, as will be shown when the chemistry of vegetable substances is treated of; at present it is to be considered as procured,-first, by the fermentation of saccharine matter; secondly, by the action of heat upon wood; the product of the former constituting vinegar, and that of the latter what was formerly called pyroligneous acid, but what is now largely employed, when purified, for most of the purposes to which vinegar is applied. It is well known that when certain vegetable juices which contain much sugar are fermented, the first operation, if the heat be not too great, is that of causing the transformation of the sugar into carbonic acid gas and alcohol, the greater part of which last remains with the fermented juice: this is called the vinous fermentation, the product being wine if the juice of the grape have been employed. Now sugar is a compound of three elements, which also form alcohol,-viz. oxygen, carbon, and hydrogen; and while a portion of the two former unite to yield the carbonic acid, a part of the three combine to form alcohol or spirit of wine.

If the action is allowed to proceed further and with access of air, the acetous fermentation ensues: the alcohol absorbs oxygen, becoming aldehyde, and eventually acetic acid. The process may be thus symbolically expressed :—

There can be scarcely a doubt that vinegar, as its name implies, was first procured, and most probably by accident, from the passage of the vinous into the acetous fermentation; and, in fact, it is now usually prepared in wine countries by exposing the wine in casks to the action of the air, at a temperature of about 76° of Fahrenheit's thermometer. Alcohol may also be converted into acetic acid by the action of finely divided platinum. If alcohol, slightly diluted, be allowed to drop on to platinum black, the oxygen condensed in the pores of the latter re-acts on the alcohol, converting it into aldehyde, which becomes, as shown above, acetic acid. This process has been employed on a large scale for the manufacture of the acid, but is now abandoned.

In this country vinegar is procured from an infusion of malt, termed wort, which is fermented in the usual way. It is then put into barrels, which are arranged in stoves, with their bungs out, and kept at a temperature of about 84° of Fahrenheit's thermometer. At this heat, which is considerably higher than that required for the vinous fermentation, carbonic acid is produced, which escapes as in the vinous fermentation; while oxygen is absorbed and thus acetic acid produced.

Vinegar thus procured is a well-known reddish-brown coloured liquid; its smell is rather pleasant and refreshing, and its taste is distinctly, but not intensely sour. The strongest malt vinegar is termed by the maker No. 24, and is calculated to contain 5 per cent. of real acetic acid; the manufacturer is allowed to mix with it one+housandth part of its weight of sulphuric acid (oil of vitriol): vinegar, therefore, is not pure acetic acid, but is a mixture of a small portion of the acid, much water, a little sulphuric, acid, spirit of wine, colouring matter, and mucilage.

Vinegar possesses the usual power of acids to redden vegetable blue colours; it combines with the alkalis, alkaline earths, and metallic oxides to form salts, which are termed acetates, some of which are of considerable importance, being largely used both in the arts and medicine.

Vinegar is purified from the sulphuric acid and colouring matter by distillation, but its smell and taste are then less agreeable: and although it is colourless, it cannot be conveniently or economically employed for the chemical purposes to which purer and stronger acetic acid is applied; not only on account of its weakness, but because the mucilage, which rises with it in distillation, renders the salts formed with it extremely difficult to purify. When vinegar is exposed to a low temperature, it is principally the watery part which freezes; and although the fluid portion is thus rendered stronger, it is unfit, on account of the presence of the colouring matter and sulphuric acid, for use as acetic acid.

The second method of obtaining acetic acid is by heating wood, as the dried branches of trees, in hollow iron cylinders, with a proper arrangement of coolers, or condensers and receivers.

The acid thus procured is called pyroligneous acid, and was at first supposed not to contain the acetic but a peculiar acid, different from all others. It is of a dark brown colour, has a strong burnt-acid smell, is very sour to the taste and acts strongly on vegetable blue colours. It contains a quantity of tar and oily matter; from these it is purified, in a considerable degree, by re-distillation, but it is ARTS AND SCI. DÍV. VOL. I.

still very impure. It is then mixed_with_chalk, becoming thus converted into acetate of lime, and the solution is concentrated by evaporation.

In order to render the acetic acid sufficiently pure, or rather to obtain an acetate fit for that purpose, the pyrolignite of lime is dissolved in water, and there is added to it a sufficient quantity of solution of sulphate of soda (Glauber's salt). The sulphuric acid contained in the sulphate of soda, and the lime in the acetate combine; and the sulphate of lime formed being very sparingly dissolved by the water, is precipitated in the state of a bulky powder: the soda of the sulphate at the same time unites with the acetic acid of the acetate of lime, forming acetate of soda. By proper evaporation crystals are obtained, which, by re-dissolving in water and again crystallising, may be rendered much purer. But if the salt should be still impure, it must be heated pretty strongly in an iron vessel. If the operation be carefully conducted, the tarry matter and other impurities only are decomposed by the action of the heat; the salt is then to be again dissolved in water and crystallised, and the crystals, after being once more pretty strongly heated to deprive them of their water, are suffi ciently pure for the manufacture of pure acetic acid.

For this object 17 parts of dried acetate of soda are distilled with 10 parts of oil of vitriol at a moderate heat. The sulphuric acid com. bines with the soda as sulphate, and the acetic acid in its mono. hydrated or glacial form is expelled and condensed in a proper receiver.

NaO, CH2O, + HO, SO, NaO,SO, + HO, C ̧н ̧ ̧.

The sulphate of soda thus formed is available for the future decom. position of the acetate of lime.

The acetic acid thus procured has the following properties: it is fluid and colourless, its smell is exceedingly pungent, and its taste very acrid and sour; if applied to the skin it occasions smarting, and even raises blisters upon it. When heated, the vapour which rises from it takes fire if a lighted taper is exposed to it. At about 45° of Fahr. a portion of this acid becomes solid and shoots into beautiful crystals; these contain no sulphurous acid, even though the product should not have been re-distilled; but a portion of sulphurous acid, formed during distillation by the decomposition of a part of the sulphuric acid, remains with the uncrystallised acid, from which it may be separated by mixing it with a small quantity of binoxide of lead (red lead) and re-distilling.

Acetic acid may also be obtained by the mere action of heat upon the binacetate of copper, or, as it is sometimes called, though improperly, distilled verdigris. The acetate of copper is first to be dried, so as to expel the greater part of the water of crystallisation, and then subjected to a pretty strong heat, in an earthen or glass retort, to which a receiver is to be properly adapted. The heat decomposes the salt, and the copper remains in the retort in the state of black or protoxide. The acid when first procured has a greenish tint, owing to the admix, ture of some protoxide of copper; it must be rendered free from this by re-distillation. This acid, though not quite so strong as that procured by the former process, is, however, still more concentrated than that required for general use.

The glacial or monohydrated acetic acid is, however, best procured by distilling dry binacetate of potash at a temperature not exceeding 550°, The following is the re-action :

(Kо, ¤ ̧¤ ̧Ó ̧ + н0, С ̧Î ̧0,) = KO, С ̧н ̧0, + по, С ̧н ̧ ̧.
Acetic Acid.

Binacetate of Potash.

Acetate of Potash.

The residual acetate of potash may be reconverted into binacetate, and repeatedly used for the same purpose. The specific gravity of monohydrated acetic acid, HO, C,H,O,, at 62° F. is 1063. It is liquid at temperatures above 55°. It crystallises at that temperature in radiating tufts of plates. Its sp. g. increases on dilution with water till three equivalents of the latter have been added, when it diminishes; and when diluted with an equal weight of water its sp. g. again becomes 1:063. Owing to this anomaly, the quantity of real acid in a solution cannot be estimated from the determination of its density. Glacial acetic acid mixes in all proportions with ether and alcohol. From the former it may be separated by the addition of water.

The uses to which acetic acid, in the state of vinegar, is applied are too well known to require notice; in the form of pyroligneous acid it is employed to preserve meat, and to impart to it the smoky flavour usually obtained by drying. Pure acetic acid is used in chemical researches, and especially for preparing various acetates. In a less pure state it is employed in the arts for preparing acetate or sugar of lead, acetate of copper or verdigris, and acetate of alumina, largely used by calico printers as a mordant.

Anhydrous acetic acid (C,H,O,) was first obtained by Gerhardt. It may be produced by distilling three parts of oxychloride of phosphorous with eight of anhydrous acetate of potash. The liquid which passes over is to be returned on the residue and re-distilled till it no longer contains chlorine: it is then to be rectified. The liquid is colourless, boiling at 279.5°, and has a very pungent, irritating smell. The specific gravity of the liquid is 1073, that of the vapour 3:47.

B

Acetic Acid (Medical properties of). Vinegar produces very different effects according to its degree of concentration; its effects are also different on the dead and living organic tissues. It acts as an effectual preservative from the putrefactive fermentation of dead organic tissues, and is hence employed as the means of forming pickles, or meat in a dried state, by simply immersing the substance in it for a few minutes. Wood vinegar, or pyroligneous acid, is most efficacious for this purpose, owing to the creasote present in it. Crude pyroligneous acid is one of the most effectual applications to timber, both to prevent the dry-rot and the ravages of insects. Concentrated acetic acid acts on the living tissues as a caustic poison; applied to the skin it causes heat, redness, and rapid inflammation. The same is the case when taken into the mouth, or applied to any mucous membrane, which it blackens like sulphuric acid. When properly diluted and used in moderation, it heightens the vitality of the stomach and greatly promotes the digestive powers. Indeed free acetic acid is one of those always present in the stomach in a healthy state, and the substitution of lactic acid for it in that organ is one of the most common accompaniments of indigestion, especially in bilious persons. The peculiar property which vinegar possesses of dissolving gelatine points out the propriety of employing it as a condiment when veal or other young meats, or fish, are taken. Its powers are heightened by having aromatic or pungent principles dissolved in it, such as chillies or taragon. In cases of slow digestion the moderate use of vinegar impregnated with these is much to be commended; but the abuse of it is to be reprobated, as productive of serious evils. This is seen in the case of ladies who employ vinegar to retain a slender figure, and who thereby induce organic diseases, even cancer of the stomach. Vinegar assists the digestion of crude vegetables, and is appropriately used for salads. Its power over the nervous system is seen in cases of poisoning with narcotic poisons and in cases of drunkenness. In the former case care must be taken that the narcotic substance is completely evacuated from the stomach before administering it, otherwise much injury may result from a powerful acetate being formed. But after the removal of the poison nothing combats more effectually the secondary symptoms than vinegar, especially if coffee be dissolved in it. Few things will restore a drunken man to his senses more speedily than giving him vinegar to drink, hence the popular custom of putting pickles into the mouth of a drunken person.

Vinegar acts as a refrigerant and as a grateful drink in fever. It may be applied externally likewise to the palms of the hands of consumptive persons, to cool the hectic flush and prevent the subsequent clammy perspirations. In cases of commencing anasarca, or loss of tone of the skin in advancing life, vinegar is a very useful wash. In a concentrated form it is beneficial in some forms of ring-worm of the scalp; though crude pyroligneous acid is preferable, owing to the creasote which it contains. The vapour of strong acetic acid, simple o aromatised, is a powerful restorative when applied to the nostrils in impending fainting, or as a means of relieving headache. It was

similar diseases, but it merely overpowers and does not destroy unwholesome odours; free ventilation is therefore preferable. Acetic acid acts as a powerful solvent both of gum resins, the action of which it thereby increases, such as assafoetida and other vegetable principles, such as those of colchicum, squill, &c., and also of metallic oxides, such as copper.

The vapour of acetic ether carefully introduced by a suitable apparatus through the Eustachian tube into the ear, is very efficacious in restoring hearing in cases of nervous deafness. (Pilcher, On the Ear.) Strong acetic acid, either alone or having the active principle of cantharides dissolved in it, furnishes a ready means of forming a blister. In cases of poisoning by strong acetic acid, chalk should be instantly administered.

Monacetine is formed by heating a mixture of glacial acetic acid and glycerine to 212° for fourteen hours. It is a neutral liquid, possessing a peculiar odour and pungent taste. Its sp. g. is 1.20. Mixed with half its volume of water, it forms a limpid mixture, which becomes opalescent when further diluted, although the glycerine does not separate. It is soluble in ether.

Diacetine is obtained by heating glacial acetic acid with excess of glycerine to 200° for three hours. It is an oil of an agreeable odour, congealing at 40°, miscible with an equal volume of water, but becoming opalescent by further dilution. It is soluble in ether and in benzole.

Triacetine is produced by heating diacetine to 482° for four hours, with fifteen to twenty times its weight of glacial acetic acid. It is a volatile, neutral, odoriferous liquid, of an ethereal and slightly bitter taste, insoluble in water, but very soluble in dilute alcohol. Sp. g. 1.174. All three acetines are decomposed by alcoholic solution of hydrochloric acid into acetic ether and glycerine.

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ACETO-BENZOIC ACID. Formula, C,,H,O,C,H2O,, C12H,O,. An anhydrous composite acid obtained by treating chloride of othyl with benzoate of soda. The re-action proceeds without the application of heat. The product is purified by washing with water, solution in ether, and final separation of the ether by a gentle heat. Anhydrous aceto-benzoic acid is an oily neutral body, heavier than water, possessing an agreeable vinous odour. It cannot be distilled without decomposition. Boiled with water, it is slowly decomposed into hydrated acetic and benzoic acids; the same decomposition is effected rapidly by solutions of the caustic alkalies, an acetate and a benzoate of the alkali being formed.

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AČETO-CINNAMIC ACID. Formula, C2,H100,C ̧H2O1, C12H2O ̧ An anhydrous acid, containing the oxides of the negative radicals othyl and cinnamyl. It is obtained by the action of chloride of othyl upon cinnamate of soda, and in its properties and re-actions closely resembles aceto-benzoic acid.

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ACETO-CUMINIC ACID. Formula, C2,H,,O,C,H,O,, CH12O. Formed by the action of chloride of othyl upon cuminate of soda. It is a composite anhydrous acid, closely resembling the aceto-benzoic acid in its properties. Alkalies convert it into acetate and benzoate. ACETO-SALICYLIC ACID. Formula, C, H,O,C ̧H2O, C12H ̧ ̧. Produced by the action of chloride of othyl upon salicylate of soda. It is a very unstable, composite, anhydrous acid, which is immediately decomposed into acetic and salicylic acids by alkaline solutions. ACETONE, a derivative of acetic acid. [KETONES.] ACETONITRYL. [METHYL, CYANIDE OF.]

ACETONINE (C,H,N,) is formed by the action of gaseous ammonia on acetone. The decomposition is produced by heating the mixture in a sealed tube at a temperature of 212°, 3(CH ̧Ó2) + 2NH, C1,H,N, + 6HO. It is an alkaline liquid, with a smell of urine, and is soluble in water, ether, and alcohol. Its combination with hydrochloric acid forms, with bichloride of platinum, a crystalline salt of an orangeyellow colour, insoluble in ether, but soluble in water and in boiling alcohol slightly acidulated with hydrochloric acid. Acetonine stands in the same relation to acetone as amarine to hydride of benzoyl, and is probably a diamine containing three equivalents of the diatomic radical propylene N, (CH)

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Acetonic acid (2HỎ, C,H,,0,0), is formed when a mixture of acetone, hydrocyanic acid, and hydrochloric acid is heated. 2(CHO) + 2(H, C2N) + 8HO + 2HCl=2HO, C, H,4010+2(NHCl). It is soluble in alcohol, ether, and water. It crystallises in prisms, and forms crystallisable salts. Acetonic acid may be regarded as lactic acid, in which two equivalents of hydrogen are replaced by two equivalents of methyl, C12H, (C2H ̧)2O,

ACETYL. This term has been applied to two distinct hypothetical radicals, viz., first to the group (C ̧Ã ̧) which Liebig regarded as the