plunder. Sajadin rallied his men, and, when the Christians
began to retire with their booty, let loose his light horse
upon them. No connected resistance was offered, and the
Turks slaughtered the fugitives until checked by the fresh
troops of the Christian right wing. Into this fight Guy's
reserve, charged with holding back the Saracens in Acre, was
also drawn, and, thus freed, 5000 men sallied out from the
town to the northward; uniting with the Saracen right wing,
they fell upon the Templars, who suffered severely in their
retreat. In the end the crusaders repulsed the relieving
army, but only at the cost of 7000 men. (R. A. S. M.)
ACRE, a land measure used by English-speaking races. Derived
from the Old Eng. acer and cognate with the Lat. ager, Gr.
agros, Sans. ajras, it has retained its original meaning
``open country,'' in such phrases as ``God's acre,'' or a
churchyard, ``broad acres,'' &c. As a measure of land, it was
first defined as the amount a yoke of oxen could plough in a
day; statutory values were enacted in England by acts of Edward
I., Edward III., Henry VIII. and George IV., and the Weights
and Measures Act 1878 now defines it as containing 4840 sq.
yds. In addition to this ``statute'' or ``imperial acre,''
other ``acres'' are still, though rarely, used in Scotland,
Ireland, Wales and certain English counties. The Scottish
acre contains 6150.4 sq. yds.; the Irish acre 7840 sq. yds.; in
Wales, the land measures erw (4320 sq. yds.), stang (3240
sq. yds.) and paladr are called ``acres''; the Leicestershire
acre (2308 3/4 sq. yds.), Westmoreland acre (6760 sq. yds.) and
Cheshire acre (10,240 sq. yds) are examples of local values.
ACRIDINE, C13H9N, in chemistry, a heterocyclic ring
compound found in crude coal-tar anthracene. It may be
separated by shaking out with dilute sulphuric acid, and
then precipitating the sulphuric acid solution with potassium
bichromate, the resulting acridine bichromate being decomposed
by ammonia. It was first isolated in 1890 by C. Graebe
and H. Caro (Ann., 1871, 158, p. 265). Many synthetic
processes are known for the production of acridine and its
derivatives. A. Bernthsen (Ann., 1884, 224, p. 1) condensed
diphenylamine with fatty acids, in the presence of zinc
chloride. Formic acid yields acridine, and the higher homologues
give derivatives substituted at the meso carbon atom,
FIG.
Acridine may also be obtained by passing the vapour of
phenylortho-toluidine through a red-hot tube (C. Graebe, Ber.,
1884, 17, p. 1370); by condensing diphenylamine with chloroform,
in presence of aluminium chloride (O. Fischer, Ber., 1884,
17, p. 102); by passing the vapours of orthoaminodiphenylmethane
over heated litharge (O. Fischer); by heating salicylic
aldehyde with aniline and zinc chloride to 260 deg. C. (R.
Mohlau, Ber., 1886, 19, p. 2452); and by distilling acridone
over zinc dust (C. Graebe, Ber., 1892, 25, p. 1735).
Acridine and its homologues are very stable compounds of feebly
basic character. They combine readily with the alkyl iodides
to form alkyl acridinium iodides, which are readily transformed
by the action of alkaline potassium ferricyanide to N-alkyl
acridones. Acridine crystallizes in needles which melt at
110 deg. C. It is characterized by its irritating action on
the skin, and by the blue fluorescence shown by solutions
of its salts. On oxidation with potassium permanganate it
yields acridinic acid (quinoline -a-b-dicarboxylic acid)
C9H5N(COOH)2. Numerous derivatives of acridine are known
and may be prepared by methods analogous to those used for
the formation of the parent base. For the preparation of
the naphthacridines, see F.Ullmann, German patents 117472,
118439, 127586, 128754, and also Ber., 1902, 35, pp. 316,
2670. Phenyl-acridine is the parent base of chrysaniline,
which is the chief constituent of the dyestuff phosphine (a
bye-product in the manufacture of rosaniline). Chrysaniline
(diamino-phenylacridine) forms red-coloured salts, which dye
silk and wool a fine yellow; and the solutions of the salts
are characterized by their fine yellowish-green fluorescence.
It was synthesized by O. Fischer and G. Koerner (Ber.,
1884, 17, p. 203) by condensing ortho-nitrobenzaldehyde with
aniline, the resulting ortho-nitro-para-diamino-triphenylmethane
being reduced to the corresponding orthoamino compound, which
on oxidation yields chrysaniline. Benzoflavin, an isomer of
chrysaniline, is also a dye-stuff, and has been prepared by
K. Oehler (English Patent9614) from meta-phenylenediamine
and benzaldehyde. These substances condense to form
tetra-aminotriphenylmethane, which, on heating with acids, loses
ammonia and yields diaminodihydrophenylacridine, from which
benzoflavin is obtained by oxidation. It is a yellow powder,
soluble in hot water. The formulae of these substances are:--
FIG.
ACRO (or ACRON), HELENIUS, Roman grammarian and
commentator, probably flourished at the end of the 2nd century
A.D. He wrote commentaries on Terence and perhaps Persius.
A collection of scholia on Horace, originally anonymous in
the earlier MSS., and on the whole not of great value, was
wrongly attributed to him at a much later date, probably
during the 15th century. It has been published by Pauly (1861)
and Hauthal (1866), together with the other Horace scholia.
See Pseudoacronis Scholia in Horatium
Vetustiora, ed. O. Keller (1902-1904).
ACROBAT (Gr. akrobatein, to walk on tiptoe), originally a
rope-dancer; the word is now used generally to cover professional
performers on the trapeze, &c., contortionists, balancers and
tumblers. Evidence exists that there were very skilful
performers on the tight-rope (funambuli) among the ancient
Romans. Modern rope-walkers (e.g. Blondin) or wire-dancers
generally use a pole, loaded at the ends, or some such
assistance in balancing, and by shifting this are enabled
to maintain, or readily to recover, their equilibrium.
ACROGENAE (``growing at the apex''), an obsolete botanical
term, originally applied to the higher Cryptogams (mosses and
ferns), which were erroneously distinguished from the lower
(Algae and Fungi) by apical growth of the stem. The lower
Cryptogams were contrasted as Amphigenae (``growing all
over''), a misnomer, as apical growth is common among them.
ACROLITHS (Gr. akrolithoi, i.e. ending in stone), statues
of a transition period in the history of plastic art, in which
the trunk of the figure was of wood, and the head, hands and
feet of marble. The wood was concealed either by gilding
or, more commonly, by drapery, and the marble parts alone were
exposed. Acroliths are frequently mentioned by Pausanias, the
best known specimen being the Athene Areia of the Plataeans.
ACROMEGALY, the name given to a disease characterized by
a true hypertrophy (an overgrowth involving both bony and
soft parts) of the terminal parts of the body, especially of
the face and extremities (Gr. akron, point, and megas,
large). It is more frequent in the female sex, between the
ages of 25 and 40. Its causation is generally associated
with disturbances in the pituitary gland, and an extract
of this body has been tried in the treatment, as one of
the recent developments in organotherapeutics; thyroid
extract has also been used, but without marked success,
On the apparent analogy of acromegaly with myxoedema.
ACRON, a Greek physician, born at Agrigentum in Sicily, was
contemporary with Empedocles, and must therefore have lived
in the 5th century before Christ. The successful measure of
lighting large fires, and purifying the air with perfumes,
to put a stop to the plague in Athens (430 B.C.), is said
to have originated with him; but this has been questioned
on chronological grounds. Suidas gives the titles of
several medical works written by him in the Doric dialect.
ACROPOLIS (Gr. akros, top, polis, city), literally
the upper part of a town. For purposes of defence early
settlers naturally chose elevated ground, frequently a hill
with precipitous sides, and these early citadels became in many
parts of the world the nuclei of large cities which grew up
on the surrounding lower ground. The word Acropolis, though
Greek in origin and associated primarily with Greek towns
(Athens, Argos, Thebes, Corinth), may be applied generically
to all such citadels (Rome, Jerusalem, many in Asia Minor,
or even Castle Hill at Edinburgh). The most famous is that
of Athens, which, by reason of its historical associations
and the famous buildings erected upon it, is generally known
without qualification as the Acropolis (see ATHENS).
ACROPOLITA (AKROPOLITES), GEORGE (1217-1282),
Byzantine historian and statesman, was born at Constantinople.
At an early age he was sent by his father to the court of
John Ducas Batatzes (Vatatzes), emperor of Nicaea, by whom
and by his successors (Theodorus II. Lascaris and Michael
VIII. Palaeologus) he was entrusted with important state
missions. The office of ``great logothete'' or chancellor
was bestowed upon him in 1244. As commander in the field
in 1257 against Michael Angelus, despot of Epirus, he showed
little military capacity. He was captured and kept for
two years in prison, from which he was released by Michael
Palaeologus. Acropolita's most important political task
was that of effecting a reconciliation between the Greek and
Latin Churches, to which he had been formerly opposed. In
1273 he was sent to Pope Gregory X., and in the following
year, at the council of Lyons, in the emperor's name he
recognized the spiritual supremacy of Rome. In 1282 he was
sent on an embassy to John II, emperor of Trebizond, and
died in the same year soon after his return. His historical
work (Xronike Supsgrafe, Annales) embraces the period
from the capture of Constantinople by the Latins (1204) to
its recovery by Michael Palaeologus (1261), thus forming a
continuation of the work of Nicetas Acominatus. It is valuable
as written by a contemporary, whose official position as great
logothete, military commander and confidential ambassador
afforded him frequent opportunities of observing the course of
events. Acropolita is considered a trustworthy authority as
far as the statement of facts is concerned, and he is easy to
understand, although he exhibits special carelessness in the
construction of his sentences. He was also the author of
several shorter works, amongst them being a funeral oration on
John Batatzes, an epitaph on his wife Eirene and a panegyric
of Theodorus II. Lascaris of Nicaea. While a prisoner
at Epirus he wrote two treatises on the procession of the
Holy Ghost ('Ekporeusis, Processio Spiritus Sancti).
Editio princeps by Leo Allatius (1651), with the editor's
famous teatise De Georgiis eorumque Scriptis; editions in
the Bonn Corpus Scriptoruin Hist. Byz., by I. Bekker
(1836), and Migne, Patrologia Graeca, cxl.; in the
Teubner series by A. Heisenberg (1903), the second volume of
which contains a full life, with bibliography; see also C.
Krumbacher, Geschichte der byzantinischen Litteratur (1897).
ACROSTIC (Gr. akros, at the end, and stichos, line
or verse), a short verse composition, so constructed that
the initial letters of the lines, taken consecutively, form
words. The fancy for writing acrostics is of great antiquity,
having been common among the Greeks of the Alexandrine
period, as well as with the Latin writers since Ennius and
Plautus, many of the arguments of whose plays were written
with acrostics on their respective titles. One of the most
remarkable acrostics was contained in the verses cited by
