甲烷

Homology \Ho*mol"o*gy\, n. [Gr. ? agreement. See {Homologous}.]
1. The quality of being homologous; correspondence; relation;
as, the homologyof similar polygons.

2. (Biol.) Correspondence or relation in type of structure in
contradistinction to similarity of function; as, the
relation in structure between the leg and arm of a man; or
that between the arm of a man, the fore leg of a horse,
the wing of a bird, and the fin of a fish, all these
organs being modifications of one type of structure.

Note: Homology indicates genetic relationship, and according
to Haeckel special homology should be defined in terms
of identity of embryonic origin. See {Homotypy}, and
{Homogeny}.

3. (Chem.) The correspondence or resemblance of substances
belonging to the same type or series; a similarity of
composition varying by a small, regular difference, and
usually attended by a regular variation in physical
properties; as, there is an homology between methane,
{CH4}, ethane, {C2H6}, propane, {C3H8}, etc., all members
of the paraffin series. In an extended sense, the term is
applied to the relation between chemical elements of the
same group; as, chlorine, bromine, and iodine are said to
be in homology with each other. Cf. {Heterology}.

{General homology} (Biol.), the higher relation which a
series of parts, or a single part, bears to the
fundamental or general type on which the group is
constituted. --Owen.

{Serial homology} (Biol.), representative or repetitive
relation in the segments of the same organism, -- as in
the lobster, where the parts follow each other in a
straight line or series. --Owen. See {Homotypy}.

{Special homology} (Biol.), the correspondence of a part or
organ with those of a different animal, as determined by
relative position and connection. --Owen.


Methane \Meth"ane\, n. [See {Methal}.] (Chem.)
A light, colorless, gaseous, inflammable hydrocarbon, {CH4};
marsh gas. It is the simplest of the aliphatic hydrocarbons.
See {Marsh gas}, under {Gas}.

{Methane series} (Chem.), a series of saturated hydrocarbons,
of which methane is the first member and type, and
(because of their general chemical inertness and
indifference) called also the {paraffin (little affinity)
series}. The lightest members are gases, as methane,
ethane; intermediate members are liquids, as hexane,
heptane, etc. (found in benzine, kerosene, etc.); while
the highest members are white, waxy, or fatty solids, as
paraffin proper.


Type \Type\, n. [F. type; cf. It. tipo, from L. typus a figure,
image, a form, type, character, Gr. ? the mark of a blow,
impression, form of character, model, from the root of ? to
beat, strike; cf. Skr. tup to hurt.]
1. The mark or impression of something; stamp; impressed
sign; emblem.

The faith they have in tennis, and tall stockings,
Short blistered breeches, and those types of travel.
--Shak.

2. Form or character impressed; style; semblance.

Thy father bears the type of king of Naples. --Shak.

3. A figure or representation of something to come; a token;
a sign; a symbol; -- correlative to antitype.

A type is no longer a type when the thing typified
comes to be actually exhibited. --South.

4. That which possesses or exemplifies characteristic
qualities; the representative. Specifically:
(a) (Biol.) A general form or structure common to a number
of individuals; hence, the ideal representation of a
species, genus, or other group, combining the
essential characteristics; an animal or plant
possessing or exemplifying the essential
characteristics of a species, genus, or other group.
Also, a group or division of animals having a certain
typical or characteristic structure of body maintained
within the group.

Since the time of Cuvier and Baer . . . the
whole animal kingdom has been universally held
to be divisible into a small number of main
divisions or types. --Haeckel.
(b) (Fine Arts) The original object, or class of objects,
scene, face, or conception, which becomes the subject
of a copy; esp., the design on the face of a medal or
a coin.
(c) (Chem.) A simple compound, used as a mode or pattern
to which other compounds are conveniently regarded as
being related, and from which they may be actually or
theoretically derived.

Note: The fundamental types used to express the simplest and
most essential chemical relations are hydrochloric
acid, {HCl}; water, {H2O}; ammonia, {NH3}; and methane,
{CH4}.

5. (Typog.)
(a) A raised letter, figure, accent, or other character,
cast in metal or cut in wood, used in printing.
(b) Such letters or characters, in general, or the whole
quantity of them used in printing, spoken of
collectively; any number or mass of such letters or
characters, however disposed.

Note: Type are mostly made by casting type metal in a mold,
though some of the larger sizes are made from maple,
mahogany, or boxwood. In the cut, a is the body; b, the
face, or part from which the impression is taken; c,
the shoulder, or top of the body; d, the nick
(sometimes two or more are made), designed to assist
the compositor in distinguishing the bottom of the face
from t`e top; e, the groove made in the process of
finishing, -- each type as cast having attached to the
bottom of the body a jet, or small piece of metal
(formed by the surplus metal poured into the mold),
which, when broken off, leaves a roughness that
requires to be removed. The fine lines at the top and
bottom of a letter are technically called ceriphs, and
when part of the face projects over the body, as in the
letter f, the projection is called a kern.
※ The type which compose an ordinary book
font consist of Roman CAPITALS, small capitals, and
lower-case letters, and Italic CAPITALS and lower-case
letters, with accompanying figures, points, and
reference marks, -- in all about two hundred
characters. Including the various modern styles of
fancy type, some three or four hundred varieties of
face are made. Besides the ordinary Roman and Italic,
some of the most important of the varieties are
※ Old English. Black Letter. Old Style.
French Elzevir. Boldface. Antique. Clarendon. Gothic.
Typewriter. Script.
※ The smallest body in common use is
diamond; then follow in order of size, pearl, agate,
nonpareil, minion, brevier, bourgeois (or two-line
diamond), long primer (or two-line pearl), small pica
(or two-line agate), pica (or two-line nonpareil),
English (or two-line minion), Columbian (or two-line
brevier), great primer (two-line bourgeois), paragon
(or two-line long primer), double small pica (or
two-line small pica), double pica (or two-line pica),
double English (or two-line English), double great
primer (or two-line great primer), double paragon (or
two-line paragon), canon (or two-line double pica).
Above this, the sizes are called five-line pica,
six-line pica, seven-line pica, and so on, being made
mostly of wood. The following alphabets show the
different sizes up to great primer.
※ Brilliant . . abcdefghijklmnopqrstuvwxyz
Diamond . . abcdefghijklmnopqrstuvwxyz Pearl . . .
abcdefghijklmnopqrstuvwxyz Agate . . .
abcdefghijklmnopqrstuvwxyz Nonpareil . . .
abcdefghijklmnopqrstuvwxyz Minion . . .
abcdefghijklmnopqrstuvwxyz Brevier . . .
abcdefghijklmnopqrstuvwxyz Bourgeois . .
abcdefghijklmnopqrstuvwxyz Long primer . . .
abcdefghijklmnopqrstuvwxyz Small pica . .
abcdefghijklmnopqrstuvwxyz Pica . . . . .
abcdefghijklmnopqrstuvwxyz English . . .
abcdefghijklmnopqrstuvwxyz Columbian . . .
abcdefghijklmnopqrstuvwxyz Great primer . . .
abcdefghijklmnopqrstuvwxyz
※ The foregoing account is conformed to
the designations made use of by American type founders,
but is substantially correct for England. Agate,
however, is called ruby, in England, where, also, a
size intermediate between nonpareil and minion is
employed, called emerald.

{Point system of type bodies} (Type Founding), a system
adopted by the type founders of the United States by which
the various sizes of type have been so modified and
changed that each size bears an exact proportional
relation to every other size. The system is a modification
of a French system, and is based on the pica body. This
pica body is divided into twelfths, which are termed
``points,'' and every type body consist of a given number
of these points. Many of the type founders indicate the
new sizes of type by the number of points, and the old
names are gradually being done away with. By the point
system type founders cast type of a uniform size and
height, whereas formerly fonts of pica or other type made
by different founders would often vary slightly so that
they could not be used together. There are no type in
actual use corresponding to the smaller theoretical sizes
of the point system. In some cases, as in that of ruby,
the term used designates a different size from that
heretofore so called.
※ 1 American 9 Bourgeois [bar] [bar] 11/2
German [bar] 2 Saxon 10 Long Primer [bar] [bar] 21/2 Norse
[bar] 3 Brilliant 11 Small Pica [bar] [bar] 31/2 Ruby 12
Pica [bar] [bar] 4 Excelsior [bar] 41/2 Diamond 14 English
[bar] [bar] 5 Pearl 16 Columbian [bar] [bar] 51/2 Agate
[bar] 6 Nonpareil 18 Great Primer [bar] [bar] 7 Minion
[bar] 8 Brevier 20 Paragon [bar] [bar] Diagram of the
"points" by which sizes of Type are graduated in the
"Point System".

{Type founder}, one who casts or manufacture type.

{Type foundry}, {Type foundery}, a place for the manufacture
of type.

{Type metal}, an alloy used in making type, stereotype
plates, etc., and in backing up electrotype plates. It
consists essentially of lead and antimony, often with a
little tin, nickel, or copper.

{Type wheel}, a wheel having raised letters or characters on
its periphery, and used in typewriters, printing
telegraphs, etc.

{Unity of type} (Biol.), that fundamental agreement in
structure which is seen in organic beings of the same
class, and is quite independent of their habits of life.
--Darwin.


Carbureted \Car"bu*ret`ed\, a.
1. (Chem.) Combined with carbon in the manner of a carburet
or carbide.

2. Saturated or impregnated with some volatile carbon
compound; as, water gas is carbureted to increase its
illuminating power. [Written also {carburetted}.]

{Carbureted hydrogen gas}, any one of several gaseous
compounds of carbon and hydrogen, some of with make up
illuminating gas.

{Light carbureted hydrogen}, methane ({CH4}), also called
{marsh gas}, and {fire damp}.
[1913 Webster +PJC]