Chapter XXIV: Appendix: The task of collecting information as to animals (5)

This reservation was formally abandoned by the British government in a convention signed at the Hague on the 2nd of November 1871; and in March 1873 the government of Batavia declared war upon Achin. Doubtless there was provocation, for the sultan of Achin had not kept to the understanding that he was to guarantee immunity from piracy to foreign traders; but the necessity for war was greatly doubted, even in Holland. A Dutch force landed at Achin in April 1873, and attacked the palace. It was defeated with considerable loss, including that of the general (Kohler).The approach of the south-west monsoon precluded the immediate renewal of the attempt; but hostilities were resumed, and Achin fell in January 1874. The natives, however, maintained themselves in the interior, inaccessible to the Dutch troops, and carried on a guerilla warfare. General van der Hoyden appeared to have subdued them in 1878-81, but they broke out again in 1896 under the traitor Taku Umar, who had been in alliance with the Dutch. He died shortly afterwards, but the trouble was not ended. General van Hentsz carried on a successful campaign in 1898 seq., but in 1901, the principal Achinese chiefs on the north coast having surrendered, the pretender-sultan fled to the Gajoes, a neighbouring inland people. Several expeditions involving heavy fighting were necessary against these in 1901-4, and a certain amount of success was achieved, but the pretender escaped, revolt still smouldered and hostilities were continued.

See P. J. Vein, Atchini en zijne betrekkingen tot Nederland (Leyden, 1873); J. A. Kruijt, Atjeh en de Atjehers (Leyden, 1877); Kielstra, Beschrijving van dcn Atjeh-oorlog (The Hague, 1883); Van Langen, Atjeh's Wesskust, Tijdschrift Aardrjjko, Genotktsch. (Amsterdam, 1888), p. 226; Renaud, Jaarboek van het Mynwezen (1882); J. Jacobs, Het famille-en Kampongleven op Groot Atjeh (Leyden, 1894); C. Snouck Hurgronje, De Atjehers (Batavia, 1894).

ACHOLI, a negro people of the upper Nile valley, dwelling on the east bank of the Bahr-el-Jebel, about a hundred miles north of Albert Nyanza. They are akin to the Shilluks of the White Nile. They frequently decorate the temples or cheeks with wavy or zigzag scars, and also the thighs with scrolls; some pierce the ears. Their dwelling-places are circular huts with a high peak, furnished with a mud sleeping-platform, jars of grain and a sunk fireplace. The interior walls are daubed with mud and decorated with geometrical or conventional designs in red, white or grey. The Acholi are good hunters, using nets and spears, and keep goats, sheep and cattle. In war they use spears and long, narrow shields of giraffe or ox hide. Their dialect is closely allied to those of the Alur, Lango and ja-Luo tribes, all four being practically pure Nilotic. Their religion is a vague fetishism. By early explorers the Acholi were called Shuli, a name now obsolete.

ACHROMATISM (Gr. a-, privative, chroma, colour), in optics, the property of transmitting white light, without decomposing it into the colours of the spectrum; ``achromatic lenses'' are lenses which possess this property. (See LENS, ABERRATION and PHOTOGRAPHY.)

ACID (from the Lat. root ac-, sharp; acere, to be sour), the name loosely applied to any sour substance; in chemistry it has a more precise meaning, denoting a substance containing hydrogen which may be replaced by metals with the formation of salts. An acid may therefore be regarded as a salt of hydrogen. Of the general characters of acids we may here notice that they dissolve alkaline substances, certain metals, &c., neutralize alkalies and redden many blue and violet vegetable colouring matters.

The ancients probably possessed little knowledge indeed of acids. Vinegar (or impure acetic acid), which is produced when wine is allowed to stand, was known to both the Greeks and Romans, who considered it to be typical of acid substances; this is philologically illustrated by the words oxus, acidus, sour, and oxos, acetus, vinegar. Other acids became known during the alchemistic period; and the first attempt at a generalized conception of these substances was made by Paracelsus, who supposed them to contain a principle which conferred the properties of sourness and solubility. Somewhat similar views were promoted by Becher, who named the principle acidum primogenium, and held that it was composed of the Paracelsian elements ``earth'' and ``water.'' At about the same time Boyle investigated several acids; he established their general reddening of litmus, their solvent power of metals and basic substances, and the production of neutral bodies, or salts, with alkalies. Theoretical conceptions were revived by Stahl, who held that acids were the fundamentals of all salts, and the erroneous idea that sulphuric acid was the principle of all acids.

The phlogistic theory of the processes of calcination and combustion necessitated the view that many acids, such as those produced by combustion, e.g. sulphurous, phosphoric, carbonic, &c., should be regarded as elementary substances. This principle more or less prevailed until it was overthrown by Lavoisier's doctrine that oxygen was the acid-producing element; Lavoisier being led to this conclusion by the almost general observation that acids were produced when non-metallic elements were burnt. The existence of acids not containing oxygen was, in itself, sufficient to overthrow this idea, but, although Berthollet had shown, in 1789, that sulphuretted hydrogen (or hydrosulphuric acid) contained no oxygen, Lavoisier's theory held its own until the researches of Davy, Gay-Lussac and Thenard on hydrochloric acid and chlorine, and of Gay-Lussac on hydrocyanic acid, established beyond all cavil that oxygen was not essential to acidic properties.

In the Lavoisierian nomenclature acids were regarded as binary oxygenated compounds, the associated water being relegated to the position of a mere solvent. Somewhat similar views were held by Berzelius, when developing his dualistic conception of the composition of substances. In later years Berzelius renounced the ``oxygen acid'' theory, but not before Davy, and, almost simultaneously, Dulong, had submitted that hydrogen and not oxygen was the acidifying principle. Opposition to the ``hydrogen-acid'' theory centred mainly about the hypothetical radicals which it postulated; moreover, the electrochemical theory of Berzelius exerted a stultifying influence on the correct views of Davy and Dulong. In Berzelius' system potassium sulphate is to be regarded as K2O+.SO3-; electrolysis should simply effect the disruption of the positive and negative components, potash passing with the current, and sulphuric acid against the current. Experiment showed, however, that instead of only potash appearing at the negative electrode, hydrogen is also liberated; this is inexplicable by Berzelius's theory, but readily explained by the ``hydrogen-acid'' theory. By this theory potassium is liberated at the negative electrode and combines immediately with water to form potash and hydrogen.

Further and stronger support was given when J. Liebig promoted his doctrine of polybasic acids. Dalton's idea that elements preferentially combined in equiatomic proportions had as an immediate inference that metallic oxides contained one atom of the metal to one atom of oxygen, and a simple expansion of this conception was that one atom of oxide combined with one atom of acid to form one atom of a neutral salt. This view, which was specially supported by Gay-Lussac and Leopold Gmelin and accepted by Berzelius, necessitated that all acids were monobasic. The untenability of this theory was proved by Thomas Graham's investigation of the phosphoric acids; for he then showed that the ortho- (ordinary), pyro- and metaphosphoric acids contained respectively 3, 2 and 1 molecules of ``basic water'' (which were replaceable by metallic oxides) and one molecule of phosphoric oxide, P2 O5. Graham's work was developed by Liebig, who called into service many organic acids---citric, tartaric, cyanuric, comenic and meconic---and showed that these resembled phosphoric acid; and he established as the criterion of polybasicity the existence of compound salts with different metallic oxides. In formulating these facts Liebig at first retained the dualistic conception of the structure of acids; but he shortly afterwards perceived that this view lacked generality since the halogen acids, which contained no oxygen but yet formed salts exactly similar in properties to those containing oxygen, could not be so regarded. This and other reasons led to his rejection of the dualistic hypothesis and the adoption, on the ground of probability, and much more from convenience, of the tenet that ``acids are particular compounds of hydrogen, in which the latter can be replaced by metals''; while, on the constitution of salts, he held that ``neutral salts are those compounds of the same class in which the hydrogen is replaced by its equivalent in metal. The substances which we at present term anhydrous acids (acid oxides) only become, for the most part, capable of forming salts with metallic oxides after the addition of water, or they are compounds which decompose these oxides at somewhat high temperatures.''

The hydrogen theory and the doctrine of polybasicity as enunciated by Liebig is the fundamental characteristic of the modern theory. A polybasic acid contains more than one atom of hydrogen which is replaceable by metals; moreover, in such an acid the replacement may be entire with the formation of normal salts, partial with the formation of acid salts, or by two or more different metals with the formation of compound salts (see SALTS). These facts may be illustrated with the aid of orthophosphoric acid, which is tribasic:-- Acid. Normal salt. Acid salts. H3PO4 Ag3PO4 Na2HPO4; NaH2PO4 Phosphoric Silver phosphate. Acid sodium acid. phosphates. Compound salts. Mg(NH4)PO4; Na(NH4)HPO4. Magnesium ammonium Microcosmic phosphate; salt. Reference should be made to the articles CHEMICAL ACTION, THERMOCHEMISTRY and SOLUTIONS, for the theory of the strength or avidity of acids.

Organic Acids.---Organic acids are characterized by the presence of the monovalent group--CO.OH, termed the carboxyl group, in which the hydrogen atom is replaceable by metals with the formation of salts, and by alkyl radicals with the formation of esters. The basicity of an organic acid, as above defined, is determined by the number of carboxyl groups present. Oxy-acids are carboxyllc acids which also contain a hydroxyl group; similarly we may have aldehyde-acids, ketone-acids, &c. Since the more important acids are treated under their own headings, or under substances closely allied to them, we shall here confine ourselves to general relations.

Classification.--It is convenient to distinguish between aliphatic and aromatic acids; the first named being derived from open-chain hydrocarbons, the second from ringed hydrocarbon nuclei. Aliphatic monobasic acids are further divided according to the nature of the parent hydrocarbon. Methane and its homologues give origin to the ``paraffin'' or ``fatty series'' of the general formula Cn H2n+1COOH, ethylene gives origin to the acrylic acid series, CnH2n-1COOH, and soon. Dibasic acids of the paraffin series of hydrocarbons have the general formula CnH2(COOH)2n; malonic and succinic acids are important members. The isomerism which occurs as soon as the molecule contains a few carbon atoms renders any classification based on empirical molecular formulae somewhat ineffective; on the other hand, a scheme based on molecular structure would involve more detail than it is here possible to give. For further information, the reader is referred to any standard work on organic chemistry. A list of the acids present in fats and oils is given in the article OILS.

Syntheses of Organic Acids.---The simplest syntheses are undoubtedly those in which a carboxyl group is obtained directly from the oxides of carbon, carbon dioxide and carbon monoxide. The simplest of all include: (1) the synthesis of sodium oxalate by passing carbon dioxide over metallic sodium heated to 350 deg. -360 deg. ; (2) the synthesis of potassium formate from moist carbon dioxide and potassium, potassium carbonate being obtained simultaneously; (3) the synthesis of potassium acetate and propionate from carbon dioxide and sodium methide and sodium ethide; (4) the synthesis of aromatic acids by the interaction of carbon dioxide, sodium and a bromine substitution derivative; and (5) the synthesis of aromatic oxy-acids by the interaction of carbon dioxide and sodium phenolates (see SALICYLIC ACID). (Carbon monoxide takes part in the syntheses of sodium formate from sodium hydrate, or soda lime (at 200 deg. -220 deg. ), and of sodium acetate and propionate from sodium methylate and sodium ethylate at 160 deg. --200 deg. . Other reactions which introduce carboxyl groups into aromatic groups ave: the action of carbonyl chloride on aromatic hydrocarbons in the presence of aluminium chloride, acid-chlorides being formed which are readily decomposed by water to give the acid; the action of urea chloride Cl.CO.NH2, cyanuric acid (CONH)3, nascent cyanic acid, or carbanile on hydrocarbons in the presence of aluminium chloride, acid-amides being obtained which are readily decomposed to give the acid. An important nucleus-synthetic reaction is the saponification of nitriles, which may be obtained by the interaction of potassium cyanide with a halogen substitution derivative or a sulphonic acid.

Acids frequently result as oxidation products, being almost invariably formed in all cases of energetic oxidation. There are certain reactions, however, in which oxidation can be successfully applied to the synthesis of acids. Thus primary alcohols and aldehydes, both of the aliphatic and aromatic series, readily yield on oxidation acids containing the same number of carbon atoms. These reactions may be shown thus:- R.CH2OH -> R.CHO -> R.CO.OH. In the case of aromatic aldehydes, acids are also obtained by means of ``Cannizzaro's reaction'' (see BENZALDEHYDE). An important oxidation synthesis of aromatic acids is from hydrocarbons with aliphatic side chains; thus toluene, or methylbenzene, yields benzoic acid, the xylenes, or dimethyl-benzene, yield methyl-benzoic acids and phthalic acids. Ketones, secondary alcohols and tertiary alcohols yield a mixture of acids on oxidation. We may also notice the disruption of unsaturated acids at the double linkage into a mixture of two acids, when fused with potash.

In the preceding instances the carboxyl group has been synthesized or introduced into a molecule; we have now to consider syntheses from substances already containing carboxyl groups. Of foremost importance are the reactions termed the malonic acid and the aceto-acetic ester syntheses; these are discussed under their own headings. The electrosyntheses call for mention here. It is apparent that metallic salts of organic acids would, in aqueous solution, be ionized, the positive ion being the metal, and the negative ion the acid residue. Esters, however, are not ionized. It is therefore apparent that a mixed salt and ester, for example KO2C.CH2.CH2.CO2C2H5, would give only two ions, viz. potassium and the rest of the molecule. If a solution of potassium acetate be electrolysed the products are ethane, carbon dioxide, potash and hydrogen; in a similar manner, normal potassium succinate gives ethylene, carbon dioxide, potash and hydrogen; these reactions may be represented:- CH3.CO2 K CH3 CO2 K* CH2.CO K CH2 CO2 K. | -> | + + | | ->|| + + CH3.CO2 K CH3 CO2 K* CH2.CO K CH2 CO2 K. By electrolysing a solution of potassium ethyl succinate, KO2C.(CH2)2CO2C2H5, the KO2C. groups are split off and the two residues .(CH2)2CO2C2H5 combine to form the ester (CH2)4(CO2C2H5)2. In the same way, by electrolysing a mixture of a metallic salt and an ester, other nuclei may be condensed; thus potassium acetate and potassium ethyl succinate yield CH3.CH2.CH2.CO2C2H5.

Reactions.--Organic acids yield metallic salts with bases, and ethereal salts or esters (q.v.), R.CO.OR', with alcohols. Phosphorus chlorides give acid chlorides, R.CO.Cl, the hydroxyl group being replaced by chlorine, and acid anhydrides, (R.CO)2O, a molecule of water being split off between two carboxyl groups. The ammonium salts when heated lose one mobecule of water and are converted into acid-amides, R.CO.NH2, which by further dehydration yield nitriles, R.CN. The calcium salts distilled with calcium formate yield aldehydes (q.v.); distilled with soda-lime, ketones (q.v.) result.

ACIDALIUS, VALENS (1567-1595), German scholar and critic, was born at Wittstock in Brandenburg. After studying at Rostock, Grelfswald and Helmstedt, and residing about three years in Italy, he settled at Breslau, where he is said to have embraced the Roman Catholic religion. Early in 1595 he accepted an invitation to Neisse, about fifty miles from Breslau, where he died of brain fever on the 25th of May, at the age of twenty-eight. His excessive application to study, and the attacks made upon him in connexion with a pamphlet of which he was reputed the author, doubtless hastened his premature end. Acidalius wrote notes on Velleius Paterculus (1590), Curtius (1594), the panegyrists, Tacitus and Plautus, published after his death.

See Leuschner, Commeutatio de A. V. Vita, Moribus, et Scriptis (1757); F. Adam, ``Der Neisser Rektor,'' in Bericht der Philomathic in Neisse (1872).

ACID-AMIDES, chemical compounds which may be considered as derived from ammonia by replacement of its hydrogen with acidyl residues, the substances produced being known as primary, secondary or tertiary amides, according to the number of hydrogen atoms replaced. Of these compounds, the primary amides of the type R.CO.NH2 are the most important. They may be prepared by the dry distillation of the ammonium salts of the acids (A. W. Hofmann, Ber., 1882, 15, p. 977), by the partial hydrolysis of the nitriles, by the action of ammonia or ammonium carbonate on acid chlorides or anhydrides, or by heating the esters (q.v.) with ammonia. They are solid crystalline compounds (formamide excepted) which are at first soluble in water, the solubility, however, decreasing as the carbon content of the molecule increases. They are easily hydrolysed, breaking up into their components when boiled with acids or alkanes. They form compounds with hydrochloric acid when this gas is passed into their ethereal solution; these compounds, however, are very unstable, being readily decomposed by water. On the other hand, they show faintly acid properties since the hydrogen of the amide group can be replaced by metals to give such compounds as mercury acetamide (CH3CONH)2Hg. Nitrous acid decomposes them, with elimination of nitrogen and the formation of the corresponding acid, RCO.NH2 + ONOH = R.COOH + N2 + H2O. When distilled with phosphoric anhydride they yield nitriles. By the action of bromine and alcoholic potash on the amides, they are converted into amines containing one carbon atom less than the original amide, a reaction which possesses great theoretical importance (A. W. Hofmann), R.CONH2 -> R.CONHBr -> R.NH2 + K2CO3 + KBr + H2O. Formamide, H.CONH2, is a liquid readily soluble in water, boillng at about 195 deg. C. with partial decomposition. Acetamide, CH3.CONH2, is a white deliquescent crystalline solid, which melts at 82-83 deg. C. and boils at 222 deg. C. It is usually prepared by distilling ammonium acetate. It is readily soluble in water and alcohol, but insoluble in ether. Benzamide, C6H5.CONH2, crystallizes in leaflets which melt at 130 deg. C. It is prepared by the action of ammonium carbonate on benzoyl chloride. It yields a silver salt which with ethyl iodide forms benzimidoethyl ether, C6H5C: (NH).OC2H5, a behaviour which points to the silver salt as being derived from the tautomeric imidobenzoic acid, C6H5C: (NH).OH (J. Tafel, Ber., 1890, 23, p. 104). On the preparation of the substituted amides from the corresponding sodamides see A. W. Titherley (Journ. Chem. Soc., 1901, 59, p. 391). The secondary and tertiary amides of the types (RCO)2NH and (RCO)3N may be prepared by heating the primary amides or the nitriles with acids or acid anhydrides to 200 deg. C. Thiamides of the type R.CSNH2 are known, and result by the addition of sulphuretted hydrogen to the nitriles, or by the action of phosphorus pentasulphide on the acid-amides. They readily decompose on heating, and are easily hydrolysed by alkanes; they possess a somewhat more acid character than the acid-amides.

ACINACES (from the Greek), an ancient Persian sword, short and straight, and worn, contrary to the Roman fashion, on the right side, or sometimes in front of the body, as shown in the bas-reliefs found at Persepolis. Among the Persian nobility it was frequently made of gold, being worn as a badge of distinction. The acinaces was an object of religious worship with the Scythians and others (Herod. iv. 62).

ACINETA (so named by C. G. Ehrenberg), a genus of suctorial Infusoria characterized by the possession of a stalk and cup-shaped sheath or theca for the body, and endogenous budding. O. Butschli has separated off the genus Metacineta (for A. mystacina), which reproduces by direct bud-fission.

ACINUS (Lat. for a berry), a term in botany applied to such fruits as the blackberry or raspberry, composed of small seedlike berries, and also to those berries themselves, or to grapestones. By analogy, acinus is applied in anatomy to similar granules or glands, or lobules of a gland.

ACIREALE, a town and episcopal see of the province of Catania, Sicily; from the town of the same name it is distant 9 m. N. by E. Pop. (1901) 35,418. It has some importance as a thermal station, and the springs were used by the Romans. It takes its name from the river Acis, into which, according to the legend, Acis, the lover of Galatea, was changed after he had been slain by Polyphemus. The rocks which Polyphemus hurled at Ulysses are identified with the seven Scogli de' Ciclopi, or Faraglioni, a little to the south of Acireale.

ACIS, in Greek mythology, the son of Pan (Faunus) and the nymph Syntaethis, a beautiful shepherd of Sicily, was the lover of the Nereid Galatea. His rival the Cyclops Polyphemus surprised them together, and crushed him to pieces with a rock. His blood, gushing forth from beneath, was metamorphosed by Galatea into the river bearing his name (now Fiume di Jaci), which was celebrated for the coldness of its waters (Ovid, Met. xiii. 750; Silius Italicus, Punica, xiv. 221).

ACKERMAN, FRANCIS (c. 1335--1387), Flemish soldier and diplomatist, was born at Ghent, and about 1380 became prominent during the struggle between the burghers of that town and Louis II. (de Male), count of Flanders. He was partly responsible for inducing Philip van Artevelde to become first captain of the city of Ghent in 1382, and at the head of some troops scoured the surrounding country for provisions and thus saved Ghent from being starved into submission. By his diplomatic abilities he secured the assistance of the citizens of Brussels, Louvain and Liege, and, having been made admiral of the Flemish fleet, visited England and obtained a promise of help from King Richard II. After Artevelde's death in November 1382, he acted as leader of the Flemings, gained several victories and increased his fame by skilfully conducting a retreat from Damme to Ghent in August 1385. He took part in the conclusion of the treaty of peace between Ghent and Philip the Bold, duke of Burgundy, the successor of Count Louis, in December 1385. Trusting in Philip, and ignoring the warnings of his friends, Ackerman remained in Flanders, and was murdered at Ghent on the 22nd of July 1387, leaving a memory of chivalry and generosity.

See Jean Froissart, Chroniques, edited by S. Luce and G. Raynaud (Paris, 1869-1897); Johannes Brandon, Chronodromon, edited hy K. de Lettenhove in the Chroniques rotatives a L'histoire de La Belgique sous la domination des ducs de Bourgogne (Brussels, 1870).

ACKERMANN, JOHANN CHRISTIAN GOTTLIEB (1756-1801), German physician, was born at Zeillenroda, in Upper Saxony, on the 17th of February 1756, and died at Altdorf on the 9th of March 1801. At the age of fifteen he became a student of medicine at Jena under E. G. Baldinger, whom he followed to Gottingen in 1773, and afterwards he studied for two years at Halle. A few years' practice at Stendal (1778-1799), where there were numerous factories, enabled him to add many valuable original observations to his translation (1780-1783) of Bernardino Ramazzini's (1633-1714) treatise on diseases of artificers. In 1786 he became professor of medicine at the university of Altdorf, in Franconia, occupying first the chair of chemistry, and then, from 1794 till his death in 1801, that of pathology and therapeutics. He wrote Institutiones Historiae Medicinae (Nuremberg, 1792) and Institutiones Therapiae Generalls (Nuremberg and Altdorf, 1784-1795), besides various handbooks and translations.

ACKERMANN, LOUISE VICTORINE CHOQUET (1813-1890), French poet, was born in Paris on the 30th of November 1813. Educated by her father in the philosophy of the Encyclopaedists, Victorine Choquet went to Berlin in 1838 to study German, and there married in 1843 Paul Ackermann, an Alsatian philologist. After little more than two years of happy married life her husband died, and Madame Ackermann went to live at Nice with a favourite sister. In 1855 she published Contes en vers, and in 1862 Contes et poesies. Very different from these simple and charming contes is the work on which Madame Ackermann's real reputation rests. She published in 1874 Poesies, premieres poesies, poesies philosophiques, a volume of sombre and powerful verse, expressing her revolt against human suffering. The volume was enthusiastically reviewed in the Revue des deux mondes for May 1871 by E. Caro, who, though he deprecated the impiete desesperee of the verses, did full justice to their vigour and the excellence of their form. Soon after the publication of this volume Madame Ackermann removed to Paris,where she gathered round her a circle of friends, but published nothing further except a prose volume, the Pensees d'un solitaire (1883), to which she prefixed a short autobiography. She died at Nice on the 2nd of August 1890.

See also Anatole France, La vie litteraire, 4th series (1892); the comte d'Haussonville, Mme. Ackermann (1882); M. Citoleux, La poesie philosophique au XIXe. siecle (vol. i., Mme. Ackermann d'apres de nombreux documents inedits, Paris, 1906).

ACKERMANN, RUDOLPH (1764-1834), Anglo-German inventor and publisher, was born on the 20th of April 1764 at Schneeberg, in Saxony. He had been a saddler and coachbuilder in different German cities, Paris and London for ten years before, in 1795, he established a print-shop and drawing-school in the Strand. Ackermann set up a lithographic press, and applied it in 1817 to the illustration of his Repository of Arts, Literature, Fashions,; &c. (monthly until 1828 when forty volumes had appeared). Rowlandson and other distinguished artists were regular contributors. He also introduced the fashion of the once popular English Annuals, beginning in 1825 with Forget-me-not; and he published many illustrated volumes of topography and travel, The Microcosm of London (3 vols., 1808-1811), Westminster Abbey (2 vols., 1812), Pine Rhine (1820), The World in Miniature (43 vols., 1821--1826), &c. Ackermann was an enterprising man; he patented (1801) a method for rendering paper and cloth waterproof, erected a factory at Chelsea for the purpose and was one of the first to illuminate his own premises with gas. Indeed the introduction of lighting by gas owed much to him. After the battle of Leipzig Ackermann collected nearly a quarter of a million sterling for the German sufferers. He died at Finchley, near London, on the 30th of March 1834.

ACKNOWLEDGMENT (from the old acknow, a compound of on- and know, to know by the senses, which passed through the forms oknow, aknow and acknow; acknowledge is formed on analogy of ``knowledge''), an admission that something has been given or done, a term used in law in various connexions. The acknowledgment of a debt, if in writing signed by the debtor or his agent, is sufficient to take it out of the Statutes of Limitations. The signature to a will by a testator, if not made in the presence of two witnesses, may be afterwards acknowledged in their presence. The acknowledgment by a woman married before 1882 of deeds for the conveyance of real property not her separate property, requires to be made by her before a judge of the High Court or of a county court or before a perpetual or special commissioner. Before such an acknowledgment can be received, the judge or commissioner is required to examine her apart from her husband, touching her knowledge of the deed, and to ascertain whether she freely and voluntarily consents to it. An acknowledgment to the right of the production of deeds of conveyance is an obligation on the vendor, when he retains any portion of the property to which the deeds relate, and is entitled to retain the deeds, to produce them from time to time at the request of the person to whom the acknowledgment is given, to allow copies to be made, and to undertake for their safe custody (Conveyancing Act 1881, s. 9). The term ``acknowledgment'' is, in the United States, applied to the certificate of a public officer that an instrument was acknowledged before him to be the deed or act of the person who executed it. .

``Acknowledgment money'' is the sum paid in some parts of England by copyhold tenants on the death of the lord of the manor.

ACLAND, CHRISTIAN HENRIETTA CAROLINE (1750-1815), usually called Lady Harriet Acland, was born on the 3rd of January 1750, the daughter of the first earl of Ilchester. In 1770 she married John Dyke Acland, who as a member of parliament became a vigorous supporter of Lord North's policy towards the American colonies, and, entering the British army in 1774, served with Burgoyne's expedition as major in the 20th regiment of foot. Lady Hurriet accompanied her husband, and, when he was wounded at Ticonderoga, nursed him in his tent at the front. In the second battle of Saratoga Major Acland was again badly wounded and subsequently taken prisoner. Lady Harriet was determined to be with him, and underwent great hardship to accomplish her object, proving herself a courageous and devoted wife. A story has been told that being provided with a letter from General Burgoyne to the American general Gates, she went up the Hudson river in an open boat to the enemy's lines, arriving late in the evening. The American outposts threatened to fire into the boat if its occupants stirred, and Lady Hnrriet had to wait eight ``dark and cold hours,'' until the sun rose, when she at last received permission to join her husband. Major Acland died in 1778, and Lady Harriet on the 21st of July 1815.

ACLAND, SIR HENRY WENTWORTH, BART. (1815-1900), English physician and man of learning, was born near Exeter on the 23rd of August 1815, and was the fourth son of Sir Thomas Dyke Acland (1787-1871). Educated at Harrow and at Christ Church, Oxford, he was elected fellow of All Souls in 1840, and then studied medicine in London and Edinburgh. Returning to Oxford, he was appointed Lee's reader in anatomy at Christ Church in 1845, and in 1851 Radcliffe librarian and physician to the Radcliffe infirmary. Seven years later he became regius professor of medicine, a post which he retained till 1894. He was also a curator of the university galleries and of the Bodleian Library, and from 1858 to 1887 he represented his university on the General Medical Council, of which he served as president from 1874 to 1887. Hn was created a baronet in 1890, and ten years later, on the 16th of October 1900, he died at his house in Broad Street, Oxford. Acland took a leading part in the revival of the Oxford medical school and in introducing the study of natural science into the university. As Lee's reader he began to form a collection of anatomical and physiological preparations on the plan of John Hunter, and the establishment of the Oxford University museum, opened in 1861, as a centre for the encouragement of the study of science, especially in relation to medicine, was largely due to his efforts. ``To Henry Acland,'' said his lifelong friend, John Ruskin, ``physiology was an entrusted gospel of which he was the solitary preacher to the heathen,'' but on the other hand his thorough classical training preserved science at Oxford from too abrupt a severance from the humanities. In conjunction with Dean Liddell, he revolutionized the study of art and archaeology, so that the cultivation of these subjects, for which, as Ruskin declared, no one at Oxford cared before that time, began to flourish in the university. Acland was also interested in questions of public health. He served on the royal commission on sanitary laws in England and Wales in 1869, and published a study of the outbreak of cholera at Oxford in 1854, together with various pamphlets on sanitary matters. His memoir on the topography of the Troad, with panoramic plan (1839), was among the fruits of a cruise which he made in the Mediterranean for the sake of his health.

ACME (Gr. akme, point), the highest point attainable; first used as an English word by Ben Jonson.

ACMITE, or AEGIRITE, a mineral of the pyroxene (q.v.) group, which may be described as a soda-pyroxene, being essentially a sodium and ferric metasilicate, NAFe(SiO3)2. In its crystallographic characters it is close to ordinary pyroxene (augite and diopside), being monoclinic and having nearly the same angle between the prismatic cleavages. There are, however, important differences in the optical characters: the birefringence of acmite is negative, the pleochroism is strong and the extinction angle on the plane of symmetry measured to the vertical axis is small (3 deg. -5 deg. ). (The hardness is 6-6 1/2, and the specific gravity 3.55. Crystals are elongated in the direction of the vertical axis, and are blackish green (aegirite) or dark brown (acmite) in colour. Being isomorphous with augite, crystals intermediate in composition between augite or diopside and aegirite are not uncommon, and these are known as aegirine-augite or aegirine-diopside.

Acmite is a characteristic constituent of igneous rocks rich in soda, such as nepheline-syenites, phonolites, &c. It was first discovered as slender crystals, sometimes a foot in length, in the pegmatite veins of the granite of Rundemyr, near Kongsbeig in Rorway, and was named by F. Stromeyer in 1821 from the Gr. akme, a point, in allusion to the pointed terminations of the crystals. Aegirite (named from Aegir, the Scandinavian sea-god) was described in 1835 from the elaeolite-syenite of southern Norway. Although exhibiting certain varietal differences, the essential identity of acmite and aegirite has long been established, but the latter and more recent name is pethaps in more general use, especially among petrologists.

ACNE, a skin eruption produced by inflammation of the sebaceous glands and hair follicles, the essential point in the disease being the plugging of the mouths of the sebaceous follicles by a ``comedo,'' familiarly known as ``blackhead.'' It is now generally acknowledged that the cause of this disease is the organism known as bacillus acnes. It shows itself in the form of red pimples or papules, which may become pustular and be attended with considerable surrounding irritation of the skin. This affection is likewise most common in early adult life, and occurs on the chest and back as well as on the face, where it may, when of much extent, produce considerable disfigurement. It is apt to persist for months or even years, but usually in time disappears entirely, although slight traces may remain in the form of scars or stains upon the skin. Eruptions of this kind are sometimes produced by the continued internal use of certain drugs, such as the iodide or bromide of potassium. In treating this condition the face should first of all be held over steaming water for several minutes, and then thoroughly bathed. The blackheads should next be removed, not with the finger-nail, but with an inexpensive little instrument known as the ``comedo expressor.'' When the more noticeable of the blackheads have been expressed, the face should be firmly rubbed for three or four minutes with a lather made from a special soap composed of sulphur, camphor and balsam of Peru. Any lather remaining on the face at the end of this time should be wiped off with a soft handkerchief. As this treatment might give rise to some irritation of the skin, it should be replaced every fourth night by a simple application of cold cream. Of drugs used internally sulphate of calcium, in pill, 1/6 grain three times a day, is a very useful adjunct to the preceding. The patient should take plenty of exercise in the fresh air, a very simple but nourishing diet, and, if present, constipation and anaemia must be suitably treated.

Rosacea, popularly known as acne rosacea, is a more severe and troublesome disorder, a true dermatitis with no relation to the foregoing, and in most cases secondary to seborrhea of the scalp. It is characterized by great redness of the nose and cheeks, accompanied by pustular enlargements on the surface of the skin, which produce marked disfigurement. Although often seen in persons who live too freely, it is by no means confined to such, but may arise in connexion with disturbances of the general health, especially of the function of digestion, and in females with menstrual disorders. It is apt to be exceedingly intractable to treatment, which is here too, as in the preceding form, partly local and partly constitutional. Of internal remedies preparations of iodine and of arsenic are sometimes found of service.

ACOEMETI (Gr. akoimetos, sleepless), an order of Eastern monks who celebrated the divine service without intermission day or night. This was done by dividing the communities into choirs, which relieved each other by turn in the church. Their first monastery was established on the Euphrates, in the beginning of the 5th century, and soon afterwards one was founded in Constantinople. Here also, c. 460, was founded by the consular Studius the famous monastery of the Studium, which was put in the hands of the Acoemeti and became their chief house, so that they were sometimes called Studites. At Agaunum (St Maurice in the Valais) a monastery was founded by the Burgundian king Sigismund, in 515, in which the perpetual office was kept up; but it is doubtful whether this had any connexion with the Eastern Acoemeti.

The Constantinopolitan Acoemeti took a prominent part in the Christological controversies of the 5th and 6th centuries, at first strenuously opposing Acacius, patriarch of Constantinople, in his attempted compromise with the monophysites; but afterwards, in Justinian's reign, falling under ecclesiastical censure for Nestorian tendencies.

See the article in Dictionary of Christian Antiquities; Wetzer und Welte, Kirchenlexicon (2nd ed.); and Herzog-Hauck, Realencyklopadie (3rd ed.); also the general histories of the time. (E. C. B.)

ACOLYTE (Gr.akolouthos, follower), the last of the four minor orders in the Roman Church. As an office it appears to be of local origin, and is entirely unknown in the Eastern Church, with the exception of the Armenians who borrowed it from the West. Before the council of Nicaea (325) it was only to be found at Rome and Carthage. When in 251 Pope Cornelius, in a letter to Fabius of Antioch, mentions among the Roman clergy forty-two acolytes, placing them after the subdeacons and before the other minor officials (see Eusebius, Hist. Ecc. lib. v. cap. 43), he gives no hint that the office was a new one, but speaks of them as holding an already established position. Their institution has therefore to be sought for at an earlier date than his pontificate. It is possible that the Liber Pontificalis refers to the office under the Latin synonym, when it says of Pope Victor (186--197) that he made sequentes cleros, a term---sequens---which Pope Gaius (283--293) uses in the sense of acolyte. While the office was well known in Rome, there is nothing to prove that it was also an order through which, as to-day, every candidate to the priesthood must pass. The contrary is a fact proved by many monumental inscriptions and authentic statements. Though the office is found at Carthage, and St Cyprian (200?-258) makes many references to acolytes, whom he used to carry his letters, this seems to be the only place in Africa where they were known. Tertullian, while speaking of readers and exorcists, says nothing about acolytes; neither does St Augustine. The Irish Church did not know them; and in Spain the council of Toledo (400) makes no mention either of the office or of the order. The Statuta Ecclesiae Antiqua (falsely called the Canons of the Fourth Council of Carthage in 397), a Gallican collection, originating in the province of Arles at the beginning of the 6th century, mentions the acolyte, but does not give, as in the case of the other orders, any form for the ordination. The Roman books are silent, and there is no mention of it in the collection known as the Leonine Sacramentary; while in the so-called Gelasian Massbook, which as we have it, is full of Gallican additions made to St Gregory's reform, there is the same silence, though in one MS. of the 10th century given by Muratori we find a form for the ordination of an acolyte. While there is frequent mention of the acolyte's office in the Ordines Romani, it is only in the Ordo VIII. (which is not earlier than the 7th century) that we find the very simple form for admitting an acolyte to his office. At the end of the mass the cleric, clad in chasuble and stole and bearing a linen bag on one arm, comes before the pope or bishop and receives a blessing. There is no collation of power or order but a simple admission to an office. The evidence available, therefore, points to the fact that the acolyte was only a local office and was not a necessary step or order for every candidate. In England, though the ecclesiastical organization came from Rome and was directed by Romans, we find no trace of such an office or order until the time of Ecgbert of York (767), the friand of Alcuin and therefore subject to Gallican influence. The Pontifical known as Ecgbert's shows that it was then in use both as an office and as an order, and Aelfric (1006) in both his pastoral epistle and canons mentions the acolyte. The conclusion, then, which seems warranted by the evidence, is that the acolyte was an office only at Rome, and, becoming an order in the Gallican Church, found its way as such into the Roman books at some period before the fusion of the two rites under Charlemagne.

The duties of the acolyte, as given in the Roman Pontifical, are identical with those mentioned in the Statuta Ecclesiae Antiqua of Arles: ``It is the duty of acolytes to carry the candlesticks, to light the lamps of the church, to administer wine and water for the Eucharist.'' It might seem, from the number forty-two mentioned by Pope Cornelius, that at Rome the acolytes were divided among the seven ecclesiastical regions of the city; but we have no proof that, at that date, there were six acolytes attached to each region. From the ancient division of the Roman acolytes into Dalatini, or those in attendance on the pope at the Lateran palace, Stationarii, or those who served at the churches where there was a ``station,'' and Regionarii, or those attached directly to the regiona, it would seem that the number forty-two was only the actual number then existing and not an official number. We get a glimpse of their duties from the Ordines Romani. When the pope rode in procession to the station an acolyte, on foot, preceded him, bearing the holy chrism; and at the church seven regionary acolytes with candles went before him in the procession to the altar, while two others, bearing the vessel that contained a pre-consecrated Host, presented it for his adoration. During the mass an acolyte bore the thurible (Ordo VI.) and three assisted at the washing of the hands. At the moment of communion the acolytes received in linen bags the consecrated Hosts to carry to the assisting priests. This office of bearing the sacrament is an ancient one, and is mentioned in the legend of Tarcisius, the Roman acolyte, who was martyred on the Appian Way while carrying the Hosts from the catacombs. The official dress of the acolyte, according to Ordo V., was a close-fitting linen garment (camisia) girt about him, a napkin hanging from the left side, a white tunic, a stole (orarium) and a chasuble (planeta) which he took off when he sang on the steps of the ambone.

At the present day, despite the earnest wish of the council of Trent (Sess. xxiii. cap. 17 d.r.), the acolyte, while remaining an order, has ceased to be essentially a clerical office, since the duties are now performed, almost everywhere, by laymen. The office has been revived, though unofficially, in the Church of England, as a result of the Tractarian movement.

See Morin, Commentarius in sacris Ecclesiae ordinationibus (Antwerp, 1685), ii. p. 209, iii. p. 152; Martene, De Antiquis Ecclesiae ritibus (Antwerp, 1739), ii. pp. 47 and 86; Mabillon, Musaeum Italicum II. for the Ordines Romani; Muratori, Liturgia Romana Vetus; Cabrol, Dictionnaire d'archeologie chretisnne et de liturgie, vol. i. col. 348-536.-. (E. TN.)

ACOMINATUS (AKOMINATOS), MICHAEL (c. 1140-1220), Byzantine writer and ecclesiastic, was born at Chonae (the ancient Colossae). At an early age he studied at Constantinople, and about 1175 was appointed archbishop of Athens. After the capture of Constantinople by the Franks and the establishment of the Latin empire (1204), he retired to the island of Coos, where he died. He was a versatile writer, and composed homilies, speeches and poems, which, with his correspondence, throw considerable light upon the miserable condition of Attica and Athens at the time. His memorial to Alexis III. Angelus on the abuses of Byzantine administration, the poetical lament over the degeneracy of Athens and the monodes on his brother Nicetas and Eustathius, archbishop of Thessalonica, deserve special mention.

Edition of his works by S. Lambros (1879--1880); Migne, Patrologia Graeca, cxl.; see also A. Ellissen, Michael Akominatos (1886), containing several pieces with German translation; F. Gregorovius, Geschichte der Stadt Athen im Mittelalter, i. (1889); G. Finlay, History of Greece, iv. pp. 133-134 (1877).

His younger brother NICETAS (Niketas), sometimes called CHONIATES, who accompanied him to Constantinople, took up politics as a career. He held several appointments under the Angelus emperors (amongst them that of ``great logothete'' or chancellor) and was governor of the ``theme'' of Philippopolis at a critical period. After the fall of Constantinople he fled to Nicaea, where he settled at the court of the emperor Theodorus Lascaris, and devoted himself to literature. He died between 1210 and 1220. His chief work is his History, in 21 books, of the period from 1180 to 1206. In spite of its florid and bombastic style, it is of considerable value as a record (on the whole impartial) of events of which he was either an eye-witness or had heard at first hand. Its most interesting portion is the description of the capture of Constantinople, which should be read with Villehardouin's and Paolo Rannusio's works on the same subject. The little treatise On the Statues destroyed by thc Latins (perhaps, as we have it, altered by a later writer) is of special interest to the archaeologist. His dogmatic work( Thesauros 'Orthodoxias, Thesaurus Orthodoxae Fidei), although it is extant in a complete form in MS., has only been published in part. It is one of the chief authorities for the heresies and heretical writers of the 12th century.

Editions: History, editio princeps, H. Wolf (1557); and in the Bonn Corpus Scriptorum Hist. Byz., 1st ed.,Bekker (1835); Rhetorical Pieces in C. Sathas, Mesaionike Bibliotheke, i. (1872); Thesaurus in Migne, Patrologia Graeca, cxxxix., cxl.; see also C. A. Sainte-Beuve, ``Geoffroy de Villehardouin'' in Causeries du Lundi, ix.; S. Reinach, ``La fin de l'empire grec'' in Esquisses Archeologiques (1888); C. Neumann, Griechische Geschichtsschreiber im 12. Jahrhundert (1888); Gibbon, Decline and Fall, ch. lx.; and (for both Michael and Nicetas) C. Krumbacher, Geschichte der byzantinischen Litteratur (1897).

ACONCAGUA, a small northern province of central Chile, bounded N. by Coquimbo, E. by Argentina, S. by Santiago and Valparaiso and W. by the Pacific. Its area is officially computed at 5487 sq. m. Pop. (1895) 113,165; (1902, official estimate based on civil registry returns) 131,255. The province is very mountainous, and is traversed from east to west by the broad valley of the Aconcagua river. The climate is hot and dry, the rainfall being too small to influence climatic conditions. The valleys are highly fertile, and where irrigation is employed large crops are easily raised. Beyond the limits of irrigation the country is semi-barren. Alfalfa and grapes are the principal products, and considerable attention is given to the cultivation of other fruits, such as figs, peaches and melons. The ``Vale of Quillota,'' through which the railway passes between Valparaiso and Santiago, is celebrated for its gardens. The Aconcagua river rises on the southern slope of the volcano Aconcagua, flows eastward through a broad valley, or bay in the mountains, and enters the Pacific 12 m. north of Valparaiso. The river has a course of about 200 m., and its waters irrigate the best and most populous part of the province. Two other rivers--the Ligua and Choapa--traverse the province, the latter forming the northern boundary line. The capital is San Felipe, on the Aconcagua river; it had a population of 11,313 in 1895, and an estimated population of 11,660 in 1902. The other chief town is Santa Rosa de los Andes (est. pop. 6854), which is a principal station on the Transandine branch of the state railway. The only port in the province is Los Vilos, in lat. 32 deg. S., from which a railway 40 m. long runs north-east to the valley of the Choapa. Another short line connects Cabildo, in the valley of the Ligua, with the state railway.

ACONCIO, GIACOMO (1492-1566?), pioneer of religious toleration, was born at Trent, it is said, on the 7th of September 1492. He was one of the Italians like Peter Martyr and Bernardino Ochino who repudiated papal doctrine and ultimately found refuge in England. Like them, his revolt against Romanism took an extremer form than Lutheranism, and after a temporary residence in Switzerland and at Strassburg, he arrived in England soon after Elizabeth's accession. He had studied law and theology, but his profession was that of an engineer, and in this capacity he found employment with the English government. He was granted an annuity of L. 60 on the 27th of February 1560, and letters of naturalization on the 8th of October 1561 (Cal. State Papers, Dom. Ser., Addenda, 1547--1566, p. 495), and was for some time occupied with draining Plumstead marshes, for which object various acts of parliament were passed at this time (Lords' Journals, vol. i., and Commons' Journals, vol. i., passim). In 1564 he was sent to report on the fortifications of Berwick (Cal. St. Pap. For Ser. 1564-1565, passim; Acts P.C., 1558-1570, p. 146); his report is now in thc Record Office (C.S.P. For., 1564-1565, No. 512).

But his real importance depends upon his contribution to the history of religious toleration. Before reaching England he had published a treatise on the methods of investigation, De Methodo, hoc est, de recte investigandarum tradendarumque Scientiarum ratione (Basel, 1558, 8vo); and his critical spirit placed him outside all the recognized religious societies of his time. On his arrival in London he had joined the Dutch Reformed Church in Austin Friars, but he was ``infected with Anabaptistical and Arian opinions'' and was excluded from the sacrament by Grindal, bishop of London. The real nature of his heterodoxy is revealed in his Stratagemata Satanae, published in 1565 and translated into various languages. The ``stratagems of Satan'' are the dogmatic creeds which rent the Christian church. Aconcio sought to find the common denominator of the various creeds; this was essential doctrine, the rest was immaterial. To arrive at this common basis, he had to reduce dogma to a low level, and his result was generally repudiated. Even Selden applied to Aconcio the remark ubi bene, nil melius; ubi male, nemo pejus. The dedication of such a work to Queen Elizabeth illustrates the tolerance or religious laxity during the early years of her reign. Aconcio found another patron in the earl of Leicester, and died about 1566.

AUTHORITIES.--Gough's Index to Parker Soc. Publ.; Strype's Grindal, pp. 62, 66; Bayle's Dictionnaire; G. Tiraboschi, Storia della lett. italiana (Florence, 1805--1813); Osterreichisches Biogr. Lexikon; Nouvelle biogr. generale; Dict. Nat. Biogr. (A. F. P.)

ACONITE (Aconitum), a genus of plants belonging to the natural order Ranunculaceae, the buttercup family, commonly known as aconite, monkshood or wolfsbane, and embracing about 60 species, chiefly natives of the mountainous parts of the northern hemisphere. They are distinguished by having one of the five blue or yellow coloured sepals (the posterior one) in the form of a helmet; hence the English name monkshood. Two of the petals placed under the hood of the calyx are supported on long stalks, and have a hollow spur at their apex, containing honey. They are handsome plants, the tall stem being crowned by racemes of showy flowers. Aconitum Napellus, common monkshood, is a doubtful native of Britain, and is of therapeutic and toxicological importance. Its roots have occasionally been mistaken for horse-radish. The aconite has a short underground stem, from which dark-coloured tapering roots descend. The crown or upper portion of the root gives rise to new plants. When put to the lip, the juice of the aconite root produces a feeling of numbness and tingling. The horse-radish root, which belongs to the natural order Cruciferae, is much longer than that of the aconite, and it is not tapering; its colour is yellowish, and the top of the root has the remains of the leaves on it.

Many species of aconite are cultivated in gardens, some having blue and others yellow flowers. Aconitum lycoctonum, wolfsbane, is a yellow-flowered species common on the Alps of Switzerland. The roots of Aconitum ferox supply the famous Indian (Nepal) poison called bikh, bish or nabee. It contains considerable quantities of the alkaloid pseudaconitine, which is the most deadly poison known. Aconitum palmatum yields another of the celebrated bikh poisons. The root of Aconitum luridum, of the Himalayas, is said to be as virulent as that of A. ferox or A. Napellus. As garden plants the aconites are very ornamental, hardy perennials. They thrive well in any ordinary garden soil, and will grow beneath the shade of trees. They are easily propagated by divisions of the root or by seeds; great care should be taken not to leave pieces of the root about owing to its very poisonous character.