Part 405

Isogonic lines (Magnetism), lines traced on the surface of the globe, or upon a chart, connecting places at which the deviation of the magnetic needle from the meridian or true north is the same.

I`so*gon"ic, a. (Zoöl.) Characterized by isogonism.

I*sog"o*nism (?), n. [Iso- + Gr. &?; offspring, generative parts.] (Zoöl.) The quality of having similar sexual zooids or gonophores and dissimilar hydrants; -- said of certain hydroids.

I`so*graph"ic (?), a. Of or pertaining to isography.

I*sog"ra*phy (?), n. [Iso- + -graphy.] Imitation of another's handwriting.

I`so*hy"e*tose` (?), a. [Iso- + Gr. "yeto`s rain.] (Phys. Geog.) Of or pertaining to lines connecting places on the earth's surface which have a mean annual rainfall. -- n. An isohyetose line.

I"so*la*ble (?), a. [See Isolate.] (Chem.) Capable of being isolated, or of being obtained in a pure state; as, gold is isolable.

I"so*late (?; 277), v. t. [imp. & p. p. Isolated (?); p. pr. & vb. n. Isolating (?).] [It. isolato, p. p. of isolare to isolate, fr. isola island, L. insula. See 2d Isle, and cf. Insulate.]

1. To place in a detached situation; to place by itself or alone; to insulate; to separate from others.

Short isolated sentences were the mode in which ancient wisdom delighted to convey its precepts.

Bp. Warburton.

2. (Elec.) To insulate. See Insulate.

3. (Chem.) To separate from all foreign substances; to make pure; to obtain in a free state.

I"so*la`ted (?), a. Placed or standing alone; detached; separated from others.

Isolated point of a curve. (Geom.) See Acnode.

I"so*la`ted*ly (?), adv. In an isolated manner.

I`so*la"tion (-l"shn), n. [Cf. F. isolation.] The act of isolating, or the state of being isolated; insulation; separation; loneliness. Milman.

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I"so*la`tor ("s*l`tr or s"*l`tr), n. One who, or that which, isolates.

I*sol"o*gous (?), a. [Iso- + Gr. lo`gos proportion.] (Chem.) Having similar proportions, similar relations, or similar differences of composition; -- said specifically of groups or series which differ by a constant difference; as, ethane, ethylene, and acetylene, or their analogous compounds, form an isologous series.

I"so*mer ("s*mr), n. [See Isomeric.] (Chem.) A body or compound which is isomeric with another body or compound; a member of an isomeric series.

I`so*mer"ic (-mr"k), a. [Iso- + Gr. me`ros part: cf. F. isomérique.] (Chem.) Having the same percentage composition; -- said of two or more different substances which contain the same ingredients in the same proportions by weight, often used with with. Specif.: (a) Polymeric; i. e., having the same elements united in the same proportion by weight, but with different molecular weights; as, acetylene and benzine are isomeric (polymeric) with each other in this sense. See Polymeric. (b) Metameric; i. e., having the same elements united in the same proportions by weight, and with the same molecular weight, but with a different structure or arrangement of the ultimate parts; as, ethyl alcohol and methyl ether are isomeric (metameric) with each other in this sense. See Metameric.

I*som"er*ide (?), n. (Chem.) An isomer. [R.]

I*som"er*ism (?), n. (Chem.) The state, quality, or relation, of two or more isomeric substances.

Physical isomerism (Chem.), the condition or relation of certain (metameric) substances, which, while chemically identical (in that they have the same composition, the same molecular weights, and the same ultimate constitution), are yet physically different, as in their action on polarized light, as dextro- and lævo-tartaric acids. In such compounds there is usually at least one unsymmetrical carbon atom. See Unsymmetrical.

I`so*mer`o*mor"phism (?), n. [Isomer + Gr. &?; form + -ism.] (Crystallog.) Isomorphism between substances that are isomeric.

{ I`so*met"ric (?), I`so*met"ric*al (?), } a. [Iso- + Gr. me`tron measure.] 1. Pertaining to, or characterized by, equality of measure.

2. (Crystallog.) Noting, or conforming to, that system of crystallization in which the three axes are of equal length and at right angles to each other; monometric; regular; cubic. Cf. Crystallization.