Part 406

Isometric lines (Thermodynamics), lines representing in a diagram the relations of pressure and temperature in a gas, when the volume remains constant. -- Isometrical perspective. See under Perspective. -- Isometrical projection, a species of orthographic projection, in which but a single plane of projection is used. It is so named from the fact that the projections of three equal lines, parallel respectively to three rectangular axes, are equal to one another. This kind of projection is principally used in delineating buildings or machinery, in which the principal lines are parallel to three rectangular axes, and the principal planes are parallel to three rectangular planes passing through the three axes.

I"so*morph (?), n. [See Isomorphous.] A substance which is similar to another in crystalline form and composition.

I`so*mor"phic (?), a. Isomorphous.

I`so*mor"phism (?), n. [Cf. F. isomorphisme.] (Crystallog.) A similarity of crystalline form between substances of similar composition, as between the sulphates of barium (BaSO4) and strontium (SrSO4). It is sometimes extended to include similarity of form between substances of unlike composition, which is more properly called homœomorphism.

I`so*mor"phous (?), a. [Iso- + -morphous.] Having the quality of isomorphism.

||I`so*nan"dra (?), n. [Iso- + Gr. &?;, &?;, a man, male.] (Bot.) A ||genus of sapotaceous trees of India. Isonandra Gutta is the principal ||source of gutta-percha. || I`so*ne*phel"ic (?), a. [Iso- + Gr. &?; a cloud.] (Phys. Geog.) Having, or indicating, an equal amount of cloudiness for a given period; as, isonephelic regions; an isonephelic line.

I`so*nic"o*tine (?), n. [Iso- + nicotine.] (Chem.) A crystalline, nitrogenous base, C10H14N2, isomeric with nicotine.

I`so*nic`o*tin"ic (?), a. (Chem.) (a) Pertaining to, or derived from, isonicotine. (b) Pertaining to, or designating, an acid isomeric with nicotinic acid.

I`so*ni*tro"so- (?). [Iso- + nitroso-.] (Chem.) A combining form (also used adjectively), signifying: Pertaining to, or designating, the characteristic, nitrogenous radical, NOH, called the isonitroso group.

I`so*nom"ic (?), a. [Gr. &?;; &?; equal + no`mos law.] The same, or equal, in law or right; one in kind or origin; analogous; similar. Dana.

I*son"o*my (?), n. [Gr. &?;: cf. F. isonomie. See Isonomic.] Equal law or right; equal distribution of rights and privileges; similarity.

I*sop"a*thy (?), n. [Iso- + Gr. &?; suffering.] (Med.) (a) The system which undertakes to cure a disease by means of the virus of the same disease. (b) The theory of curing a diseased organ by eating the analogous organ of a healthy animal. Mayne. (c) The doctrine that the power of therapeutics is equal to that of the causes of disease.

I`so*pep"sin (?), n. [Iso- + pepsin.] (Physiol. Chem.) Pepsin modified by exposure to a temperature of from 40° to 60° C.

I`so*per`i*met"ric*al (?), a. [Gr. &?;; &?; equal + &?; circumference: cf. F. isopérimètre. See Perimeter.] (Geom.) Having equal perimeters of circumferences; as, isoperimetrical figures or bodies.

I`so*per*im"e*try (?), n. (Geom.) The science of figures having equal perimeters or boundaries.

I`so*pi*es"tic (?), a. [Iso- + Gr. &?; to press.] (Thermodynamics) Having equal pressure.

Isopiestic lines, lines showing, in a diagram, the relations of temperature and volume, when the elastic force is constant; -- called also isobars.

||I`so*pleu"ra (?), n. pl. [NL. See Iso-, and Pleura.] (Zoöl.) A ||subclass of Gastropoda, in which the body is symmetrical, the right ||and left sides being equal. || The intestine terminates at the posterior end of the body, and the gills and circulatory and reproductive organs are paired. It includes the chitons (Polyplacophora), together with Neomenia and Chætoderma, which are wormlike forms without a shell.

I"so*pod (?), a. (Zoöl.) Having the legs similar in structure; belonging to the Isopoda. -- n. One of the Isopoda.

||I*sop"o*da (?), n. pl. [NL. See Iso-, and -poda.] (Zoöl.) An order of ||sessile-eyed Crustacea, usually having seven pairs of legs, which are ||all similar in structure. || The body is usually depressed, with the abdominal segments short, and often consolidated in part. The branchiæ are on the abdominal appendages. The group includes the terrestrial pill bugs and sow bugs, with numerous marine forms. See Arthrostrata, Gribble.

I`so*pod"i*form (?), a. [Isopod + -form.] (Zoöl.) Having the shape of an isopod; -- said of the larvæ of certain insects.

I*sop"o*dous (?), a. Same as Isopod.

I`so*pog"o*nous (?), a. [Iso- + Gr. &?; beard.] (Zoöl.) Having the two webs equal in breadth; -- said of feathers.

I"so*prene (?), n. [Etymol. uncertain.] (Chem.) An oily, volatile hydrocarbon, obtained by the distillation of caoutchouc or gutta-percha.

I`so*pyc"nic (?), a. [Iso- + Gr. pykno`s dense.] (Physics) Having equal density, as different regions of a medium; passing through points at which the density is equal; as, an isopycnic line or surface.

I`so*pyc"nic, n. (Physics) A line or surface passing through those points in a medium, at which the density is the same.

I*sor"cin (?), n. [Iso- + orcin.] (Chem.) A crystalline hydrocarbon derivative, metameric with orcin, but produced artificially; -- called also cresorcin.

I`sor*rop"ic (?), a. [Gr. 'iso`rropos in equipoise; 'i`sos equal + "roph` downward inclination or momentum.] Of equal value.