ÆSCHYNITE

Eschynite (Gr. aloxúvn, disgrace). A tita-
nate of zirconia and cerium, found in Felspar, in
the Ilmen range of mountains, near Miask in
Siberia. It occurs in oblique rhombie prisms,
terminated by four-sided pyramids, which are
generally striated and imperfect. The crystals
are nearly black and opaque, or inclining to
brownish-yellow when translucent. The name
was given by Berzelius, in allusion to the in-
ability of chemists, at the time of the discovery
of the mineral, to separate the titanic acid and
zirconia which enter into its composition.
Esculaceæ. A natural order of exogenous
plants, consisting of the horse-chestnut, Escu-
lus hippocastanum, and other nearly allied
species. They are all either shrubs or trees
inhabiting temperate regions, and nearly corre-
spond with the horse-chestnut in the structure
Their seeds contain starch
of the flowers.
mixed with the detergent matter called sapo-
nine, and their bark is in some cases bitter and
astringent.

Esculapius (Gr. 'Aσêλŋwιós). ́ In Mytho-
logy. He was the son of Apollo and the
nymph Coronis. He was worshipped as the
god of surgery and medicine; but the older
poets, as Homer and Pindar, mention him only
The chief
as a hero well skilled in these arts.
seat of his worship was Epidaurus, where he
was represented as an old man, with a mantle
and staff, round which a serpent is twined.

Esculine. A peculiar substance contained
in the bark of the horse-chestnut tree (Escu-
lus hippocastanum): it appears in the form of
a white crystalline powder, and when dissolved
in very minute quantities in water, communi-
cates a blue opalescence to it.

In the
Esthetic (Gr. aioðŋriós, having the power
of perception by means of the senses).
Fine Arts, that which derives the first principles
in all the arts from the effect which certain
combinations have on the mind, as connected
The aesthetic quality of a work
with nature.
of art is that which is apprehended by the per-
ceptions or feeling, irrespective of the under-
standing.

Esthna. A name applied by Fabricius to
a genus of dragon-flies, characterised by having
the wings expanded when at rest, and the divi-
sions of the lip equal.

Estivation (Lat. æstivus, of or belonging to
summer). A figurative expression, employed to
indicate the manner in which the parts of a flower
Botanists
are arranged before they unfold.
speak of the aestivation of the calyx, of the co-
rolla, and of the stamens.

Estuary, or Estuary (Lat. æstuarium).
In Geography, was anciently understood to be
any creek, frith, or arm of the sea, in which
the tide ebbs and flows (Plin. Epist. lib. ix, ep.
33); but it is now applied to designate those
parts of the channels of certain rivers con-
tiguous to the sea, in which the water is either
salt or brackish, and in which the ebb and flow
of the sea is distinctly perceptible, and there is
little or no current.

symnetæ (Gr. aira). A class of VOL. I.

33

ÆTHUSA

Greek tyrants, who acquired their power from
having been invested by the citizens with su
preme authority, and placed in command of the
military force, but only for a given time, and to
deal with some definite emergency, but who be
came practically despots for life. (Grote, His-
tory of Greece, part ii. ch. ix.)

Aëtheogamous (Gr. åhens, unusual, and
yuos, marriage). A name contrived to express
more clearly the nature of what are called
author of the name that the mode of propaga-
Cryptogamic plants; it being the opinion of the
tion among such plants was not hidden, but
only of an unusual nature. It has been confined
by De Candolle to such as have vessels, as well
as cellular tissue, in their organisation. In this
sense it includes ferns, lycopodiums, and their
allies.

Ether. [ETHER.]

40

30

20

10

0

10

Ethogen (Gr. alowy, brilliant, yiyvoμai, I remarkable for the intense luminosity which it become). A compound of nitrogen with boron, Ethrioscope (Gr. aïopios, clear, and σkowéw, exhibits in the flame of the blowpipe. I view). An instrument invented by Sir John Leslie for measuring the relative degrees of cold produced by the pulsations from a clear sky. It consists of a differential thermospheroidal cup of metal, the inmeter, adapted to the cavity of a terior of which is highly polished, in such a manner that one of the balls occupies a focus of the spheroid; while the orifice of the cup through the other focus, perpenis formed by a plane passing same metal is fitted to the mouth dicular to the axis. A lid of the of the cup, and only removed when an observation is to be made. Suppose the cup exposed to a clear sky; the cold pulses darted from the upper regions of the atmosphere, which enter the orifice of the cup, are reflected from the polished surface upon at the side of the cup in its widest part, is the ball A in the focus, while the ball B, lodged nearly screened from them, or receives only the small number which fall obliquely upon it. grees of cold, the effect of which is immediately The two balls are thus exposed to different deThe effect apparent, by the rise of the liquor in the stem of the thermometer, in consequence of the contraction of the air in the ball A. may be augmented by covering the ball B, or silver leaf. It is evident that the instrument which is out of the focus, with a coat of gold is equally adapted to measure the effects of the radiation of heat, which will be manifested by the descent of the liquor in the stem. When applied to this purpose, however, the metallic cup becomes unnecessary; the hot pulses being mostly thrown back from the bright surface of the gilt ball, while they produce their full effect on the naked or sentient one. (Encyc. Brit., art. CLIMATE.) æthrioscope is thus converted into a pyroscope.

The

Ethusa (Gr. aleovoa, part. of alow, I burn).

D

A genus of the Umbelliferous family, containing a term prefixed to a movement, showing that one common species, a weed in most cultivated it is to be performed in a smooth, tender, and ground. This plant, E. Cynapium, or fool's affecting manner, and, therefore, rather inparsley, is an acrid poison, and from its re-clining to slowness than the reverse. semblance to common plain-leaved parsley Afidavit (Low Lat. affido, Iconfirm by oath). should be carefully discriminated. When in In Law, an oath in writing, sworn before some flower it is readily known by the presence of a person who has authority to administer it. Affifew deflexed narrow involucral leaflets on the davits, though once common in private matters, outer side of each partial umbel. A safe mode, are now used in legal proceedings only. however, of avoiding at all times unpleasant consequences from its being mistaken for parsley, is to cultivate and use only the curlyleaved varieties of the latter: the leaves of the fool's parsley being perfectly flat.

Aëtiaioi (Gr. from derós, a pediment). In Architecture, the name given by the Greek architects to the slabs forming the face of the tympanum of a pediment. This word occurs in the Athenian inscription now in the British Museum, brought to England by Dr. Chandler, and relating to the survey of some temple at Athens.

Etiology (Gr. airía, a cause, and Aóyos, discourse). The doctrine of the causes of disease.

Affiliation (Lat. affilio, I adopt). In Law, the assignment of a child to a parent by legal authority; as where the father of a bastard child is designated on the testimony of the woman, and the expenses of maintaining it cast upon him. By the Poor Law Amendment Act, s. 72, this can now only be done, after sufficient notice to the party intended to be charged, by an order of the court of quarter sessions, on the testimony of the woman, corroborated as to some material fact by other evidence. [BASTARD.]

Affiliated Societies, in Politics, are local societies, depending on a central society with which they correspond, and from which they receive directions. Such were the provincial Jacobin clubs, founded on the model of the Jacobin club of Paris. Such, also, were the Corresponding Societies in England, for the suppression of which the statute 39 G. 3, c. 79,

Etites (Gr. derós, an eagle). A term given by Pliny to hollow stones composed of several crusts one within another. By Kirwan the name is used to denote those kinds of iron-ore (clay-ironstone), which are composed of a reni-was chiefly passed. form or globular crust of oxide investing an ochreous kernel. The name originated in the ancient belief that such stones formed part of an eagle's nest.

Affectation (Lat. affectatio). In the Fine Arts, an artificial show arising from the want of simplicity either in colouring, drawing, or action. Also, the over-charging any part of a composition with an artificial or deceitful ap

pearance.

Affected, or Adfected (Lat. affectus). A term used in Algebra. When applied to an equation, it signifies that two or more powers of the unknown quantity enter into the equation: thus, x2+ax+b=0 is termed an adfected quadratic, to distinguish it from x2+c=0; which is a pure quadratic. When the term is applied to a quantity, it implies that the latter has a coefficient, or a proper sign: thus, in the quantity+ 2x, x is said to be affected with the coefficient 2, and with the sign+. Dr. Hutton thinks the term affected was introduced into Algebra by Vieta.

Afferent (Lat. afferens). The term, in Anatomy, applied to those lymphatic vessels which enter the lymphatic glands, subdivide, and form tortuous plexuses therein, whence other vessels proceed, converge, and unite into two or more efferent vessels which are larger than the afferent ones, and proceed towards the main trunk called 'thoracic duct." The term afferent has also been applied to those nerves which convey impressions to the central axis, and which Hartley called 'sensory' nerves, in contradistinction to the efferent or 'motory' nerves.

Affetto, or Affettuoso (Ital.). In Music,

Affinity (Lat. affinitas). A relation of animals to one another, in the similarity of a greater proportion of their organisation: thus, a porpoise is said to have an affinity to man, because of its resemblance to him in the respiratory, circulating, and generative systems, in the brain, eye, ear, &c.; while it is said to have an analogy to a fish, because the resemblance is confined to external form. In short, affinity is that degree of relationship by which, in forming a concatenated series of animals, we pass from one to another by the closest gradations.

AFFINITY. In Botany, when the relation which plants or groups of plants bear to one another is very close, and depends on some striking resemblance between important organs. The term is used in contradistinction to analogy, when the resemblance lies between organs of less importance. Thus the foliage of Lathyrus Nissolia resembles that of a grass; but there is no affinity between the dicotyledonous Lathyrus and the monocotyledonous grass.

AFFINITY. In Law, as distinguished from consanguinity, signifies the relation which a man and woman by marriage contract towards the kindred of each other. From early times in the Christian church, this kind of relationship was esteemed to have the same effect as relationship by consanguinity in causing impediments to marriage; a rule chiefly founded, or alleged to be so, on the received interpretation of the eighteenth chapter of Leviticus. Until 1835, marriages of this class were voidable only in England. In that year an act passed (5 & 6 Will. 4, c. 54) which prohibited

AFFINITY, CHEMICAL

them absolutely for the future, at the same time rendering valid those which existed. Affinity, Chemical. The attractive force by which dissimilar substances combine with each other to produce chemical compounds. All natural and artificial substances are either simple or compound. The metals, for instance, are simple substances-no one of them having been as yet decomposed: water is a compound; it may be resolved into oxygen and hydrogen gases, which are therefore called its component parts. To enable substances to exert their mutual affinities, or to act chemically upon each other, the opposing powers of matter must be overcome, and they must be placed under circumstances favourable to the exertion of their mutual chemical attractions. Two solid bodies seldom combine, in consequence of their imperfect contact, and the immobility of their particles; hence the old axiom, corpora non agunt, nisi fluida. But to this there are exceptions: ice and salt, for instance, run down into liquid brine; dry oxalic acid and dry lime unite; and when sulphur and chlorate of potash are rubbed together, they act violently on each other. Even when one or both substances are fluid, heat is often requisite to diminish cohesion, and promote affinity: thus, mercury and and iron combine with melted sulphur; oxygen and hydrogen, and oxygen and carbon, require heat to effect their union. In some cases the action of the solar rays excites and increases affinity, as in the combination of hydrogen and chlorine.

The investigation of the relative proportions in which bodies combine, forms the basis of the atomic theory, or doctrine of chemical equivalents.

these compounds the relative proportions of
oxygen being as 1, 2, and 3. Again, 14 parts
of nitrogen combine with 8, 16, 24, 32, and 40
of oxygen, forming five distinct compounds, in
which the relative proportions of the oxygen
are as 1, 2, 3, 4, and 5.

Where the combining substances are either
naturally gaseous, or where they may be hypo-
thetically so considered, it is obvious that, as
their weights bear these simple relations to each
other, their bulks or volumes will do so likewise:
thus, in the case of the compounds just noticed,
1 volume of nitrogen will combine respec-
tively with, 1, 1, 2, and 2 volumes of
oxygen; or, what amounts to the same thing,
2 volumes of nitrogen will combine with 1, 2,
3, 4, and 5 volumes of oxygen.

As bodies thus combine with each other in definite proportions, it is obvious, that if we select any one substance as unity, or = 1, all other substances may be represented by numbers equal to the weights in which they respectively combine with each other, and with the unit. Upon this principle of numeric representation, hydrogen, which is the lightest known substance, is assumed as unity; the compound of hydrogen with oxygen is water, in which 1 part by weight of hydrogen is combined with 8 of oxygen, to form 9 of water; hence, in a table of atomic weights, definite proportionals, or chemical equivalents, (for all these terms have been applied to such numbers), we have

Hydrogen represented by 1
Oxygen
Water

8
9

And in the above series of nitric compounds we have, in the first of them, 14 of nitrogen combined with 8 of oxygen; and, accordingly, calling 14 the equivalent of nitrogen, and 8 the equivalent of oxygen, we have the following equivalents of their compounds; and it may be presumed that these numbers represent the weights of the combining atoms of those bodies:—

Atoms

Equivalents, or combining weights,

=

gen gen

1 +1

1 + 2

1

gen
14 +
14+ 16
14 + 24
14 + 32
14 + 40

gen

8

=

=

Many substances seem to unite in all proportions; but these are not strict cases of chemical combination: thus, water and suland ether, mix phuric acid, and alcohol together in any quantities. Others unite indefinitely, up to a certain point: water, for instance, dissolves salt, in variable quantity, till the solution is saturated: we thus find that a given quantity of water is only able to retain a certain weight of salt in permanent solution. In these cases of indefinite combination, the affinities of the combining sub-for- of oxy- of nitro- of oxystances are usually feeble; but where their affinities or attractive powers are energetic, there is a remarkable tendency to combine in certain proportions only. Thus, sulphuric acid and lime unite in the proportions of 40 of the acid to 28 of the lime, and in no other or intermediate quantity: in such cases the acid and the base are said to neutralise each other; and such compounds are often called neutral salts, that is, salts in which the leading characters of the component parts are no longer perceptible, which are neither acid nor alkaline. bodies combine in more than one proportion, which is often the case, the second, third, &c., proportions are simple multiples of the first: thus, 16 parts of sulphur combine respectively with 8, 16, and 24 of oxygen; in

35

=

Equivalents of the
compounds

22 nitrous oxide

30 nitric oxide

38 hyponitrous acid
46 nitrous acid
54 nitric acid

+ 3 1+ 4 1 + 5 This table also shows the nomenclature commonly applied to the compounds; the termination ous indicating the minimum of oxygen, the termination ie the maximum; the term oxide implying generally all those combinations When of oxygen which are not sour, such being called acids. More frequently the relative proportions of oxygen in the oxides are designated by the first syllable of the Greek ordinal numerals: thus we have protoxides, deutoxides, tritoxides, &c.; and when the base is saturated

D 2

AFFINITY, CHEMICAL

with oxygen, the compound is termed a peroxide. When the same substance forms three or four acids, the term hypo is conveniently introduced with the termination ous or ic, as shown in the following table of acids of sulphur :

Atoms of

Equivalents of

sulphur oxygen sulphur oxygen

1 + 1

1 + 2 1+ 3

16 +

8

16

=

24

16 +
16+

=

Equivalents of the
acids

24 hyposulphurous
32 sulphurous
40 sulphuric

AFRICA

utterly impossible, by any à priori reasoning, to determine what will be the consequence of chemical combination: useless elements produce useful compounds, and useless compounds yield useful elements.

Another important and curious consequence of chemical action is change of colour: the vegetable blues are generally reddened by acids, and rendered green by alkalis; the alkalis render many of the reds purple; and of the yellows, brown: chlorine destroys most colours; so does the joint action of light, air, and moisture. [NOTATION, CHEMICAL.]

There is also an acid of sulphur intermediate between sulphurous and sulphuric, composed of 1 atom of hyposulphurous acid and 1 of sulphurous acid; (24+32=56) or of 2 atoms of sulphur and 3 of oxygen: this is appropriately called the hyposulphuric acid. The terms ssqui and bi are sometimes used to designate intermediate and double compounds of acids, or other bodies with bases: thus, we have three compounds of carbonic acid with ammonia, or affirmation is punishable as perjury. in which 1 proportional or atom of ammonia is respectively combined with 1, 13, and 2 of carbonic acid, and these we call the carbonate, sesquicarbonate, and bicarbonate of ammonia. For a table of the equivalent numbers of the simple substances, see EQUIVALENTS.

Affirmation (Lat. affirmatio). In English Law, a solemn declaration made, in cases authorised by law, by persons statutably relieved from the necessity of taking oaths. This relief, early granted to Quakers and members of some other persuasions, was extended by the Common Law Procedure Act, 1854, to all persons having conscientious objections. A false declaration

Change of form and change of properties are the common consequences of chemical affinity. We observe, 1. Solids forming liquids (ice and salt). 2. Solids forming gases (explosion of gunpowder). 3. A solid and a liquid producing a solid (lime and water). 4. A solid and a liquid producing a liquid (all common cases of solution; as of salt and sugar in water). 5. Liquids producing solids (solution of carbonate of potassa mixed with muriate of lime). 6. Liquids producing gases (alcohol and nitric acid). 7. Gases producing solids (ammonia and muriatic acid). 8. Gases producing liquids (chlorine and olefiant gas).

The density of bodies is also materially affected by chemical combination; the density of a compound is very rarely the mean of its components, but generally increased: thus, almost all gaseous compounds occupy less bulk than their elementary gases in a separate state; there are, however, cases in which 1 volume of one gas, combined with 1 volume of another, produce exactly 2 volumes of a compound gas, the density of which is, of course, the mean of that of its components; and again, in the combinations of some of the metals with each other, and with sulphur, the density of the compound is below the mean of its elements. When certain liquids are mixed, great and immediate increase of density ensues, and much heat is evolved (sulphuric acid and water). Change of form and of density are often attended by remarkable changes in other qualities: thus, tasteless bodies produce active compounds (oil of vitriol is composed of oxygen, sulphur, and water), and active substances produce inert compounds (sulphuric acid and caustic potash produce the inert salt, sulphate of potash); so that it is

Affirmative. In Logic, this term denotes the quality of a proposition which asserts the agreement of the predicate with the subject. Affirmative Quantity. [POSITIVE QUANTITY.]

Affirmative Sign or Positive Sign, The sign of addition, marked +, meaning plus, or more. Dr. Hutton observes, that the early writers on algebra used the word plus in Latin, or piu in Italian, for addition, and afterwards the initial p only as a contraction, as they used minus or meno, or the initial m only, for subtraction; and thus their operations were denoted in Italy by Lucas de Burgo, Tartalea, and Cardan, while the signs+and -were employed much about the same time in Germany by Stifelius, Scheubelius, and others, to denote the same operations.

Affix. In Grammar, a syllable attached to the end of a class of words, determining their meaning. Thus, a class of adverbs in English is determined by the affix ly; strongly, weakly, &c. A prefix is a syllable so attached at the beginning.

In

Affrontée (Fr. affronter, to face). Heraldry, a term applied to animals placed to face each other.

Afrancesados (Span.). In Modern History, adenomination given in Spain to the party which attached itself to the cause of the French, or of the intrusive king Joseph, during the war of independence, 1808-1814.

Africa. The continent of Africa is about 5300 miles in length from north to south, and nearly as much in extreme breadth from east to west; but its shape is triangular, and its area does not exceed twelve millions of square miles. The total length of its coast line is less than 15,000 miles, showing an amount of deviation from a straight line, and a smallness of indentstion, extremely remarkable. It has few navigable rivers, and the interior is therefore reached with difficulty. The mouths of its rivers are all swampy, and extremely subject to malaria. Its lakes are numerous and perhaps occasionally