Or·tho- pref.
 1. A combining form signifying straight, right, upright, correct, regular; as, orthodromy, orthodiagonal, orthodox, orthographic.
 2. Chem. A combining form (also used adjectively), designating: (a) Inorganic Chem. The one of several acids of the same element (as the phosphoric acids), which actually occurs with the greatest number of hydroxyl groups; as, orthophosphoric acid.  Cf. Normal.  (b) Organic Chem. Connection with, or affinity to, one variety of isomerism, characteristic of the benzene compounds; -- contrasted with meta- or para-; as, the ortho position; hence, designating any substance showing such isomerism; as, an ortho compound.
 Note: ☞ In the graphic representation of the benzene nucleus (see Benzene nucleus, under Benzene), provisionally adopted, any substance exhibiting double substitution in adjacent and contiguous carbon atoms, as 1 & 2, 3 & 4, 4 & 5, etc., is designated by ortho-; as, orthoxylene; any substance exhibiting substitution of two carbon atoms with one intervening, as 1 & 3, 2 & 4, 3 & 5, 4 & 6, etc., by meta-; as, resorcin or metaxylene; any substance exhibiting substitution in opposite parts, as 1 & 4, 2 & 5, 3 & 6, by para-; as, hydroquinone or paraxylene.

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 Sym·bol n.
 1. A visible sign or representation of an idea; anything which suggests an idea or quality, or another thing, as by resemblance or by convention; an emblem; a representation; a type; a figure; as, the lion is the symbol of courage; the lamb is the symbol of meekness or patience.
    A symbol is a sign included in the idea which it represents, =\e. g., an actual part chosen to represent the whole, or a lower form or species used as the representative of a higher in the same kind.\=   --Coleridge.
 2. Math. Any character used to represent a quantity, an operation, a relation, or an abbreviation.
 Note: ☞ In crystallography, the symbol of a plane is the numerical expression which defines its position relatively to the assumed axes.
 3. Theol. An abstract or compendium of faith or doctrine; a creed, or a summary of the articles of religion.
 4.  That which is thrown into a common fund; hence, an appointed or accustomed duty. [Obs.]
    They do their work in the days of peace . . . and come to pay their symbol in a war or in a plague.   --Jer. Taylor.
 5. Share; allotment. [Obs.]
    The persons who are to be judged . . . shall all appear to receive their symbol.   --Jer. Taylor.
 6. Chem. An abbreviation standing for the name of an element and consisting of the initial letter of the Latin or New Latin name, or sometimes of the initial letter with a following one; as, C for carbon, Na for sodium (Natrium), Fe for iron (Ferrum), Sn for tin (Stannum), Sb for antimony (Stibium), etc.  See the list of names and symbols under Element.
 Note: ☞ In pure and organic chemistry there are symbols not only for the elements, but also for their grouping in formulas, radicals, or residues, as evidenced by their composition, reactions, synthesis, etc. See the diagram of Benzene nucleus, under Benzene.
 Syn: -- Emblem; figure; type. See Emblem.


 Ben·zene n.  Chem. A volatile, very inflammable liquid, C6H6, contained in the naphtha produced by the destructive distillation of coal, from which it is separated by fractional distillation. The name is sometimes applied also to the impure commercial product or benzole, and also, but rarely, to a similar mixed product of petroleum.
 Benzene nucleus, Benzene ring Chem., a closed chain or ring, consisting of six carbon atoms, each with one hydrogen atom attached, regarded as the type from which the aromatic compounds are derived. This ring formula is provisionally accepted as representing the probable constitution of the benzene molecule, C6H6, and as the type on which its derivatives are formed.

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 Chain n.
 1. A series of links or rings, usually of metal, connected, or fitted into one another, used for various purposes, as of support, of restraint, of ornament, of the exertion and transmission of mechanical power, etc.
    [They] put a chain of gold about his neck.   --Dan. v. 29.
 2. That which confines, fetters, or secures, as a chain; a bond; as, the chains of habit.
 Driven down
 To chains of darkness and the undying worm.   --Milton.
 3. A series of things linked together; or a series of things connected and following each other in succession; as, a chain of mountains; a chain of events or ideas.
 4. Surv. An instrument which consists of links and is used in measuring land.
 Note: ☞ One commonly in use is Gunter's chain, which consists of one hundred links, each link being seven inches and ninety-two one hundredths in length; making up the total length of rods, or sixty-six, feet; hence, a measure of that length; hence, also, a unit for land measure equal to four rods square, or one tenth of an acre.
 5. pl. Naut. Iron links bolted to the side of a vessel to bold the dead-eyes connected with the shrouds; also, the channels.
 6. Weaving The warp threads of a web.
 Chain belt Mach., a belt made of a chain; -- used for transmitting power.
 Chain boat, a boat fitted up for recovering lost cables, anchors, etc.
 Chain bolt (a) Naut. The bolt at the lower end of the chain plate, which fastens it to the vessel's side. (b) A bolt with a chain attached for drawing it out of position.
 Chain bond. See Chain timber.
 Chain bridge, a bridge supported by chain cables; a suspension bridge.
 Chain cable, a cable made of iron links.
 Chain coral Zool., a fossil coral of the genus Halysites, common in the middle and upper Silurian rocks. The tubular corallites are united side by side in groups, looking in an end view like links of a chain. When perfect, the calicles show twelve septa.
 Chain coupling. (a) A shackle for uniting lengths of chain, or connecting a chain with an object. (b) Railroad Supplementary coupling together of cars with a chain.
 Chain gang, a gang of convicts chained together.
 Chain hook Naut., a hook, used for dragging cables about the deck.
 Chain mail, flexible, defensive armor of hammered metal links wrought into the form of a garment.
 Chain molding Arch., a form of molding in imitation of a chain, used in the Normal style.
 Chain pier, a pier suspended by chain.
 Chain pipe Naut., an opening in the deck, lined with iron, through which the cable is passed into the lockers or tiers.
 Chain plate Shipbuilding, one of the iron plates or bands, on a vessel's side, to which the standing rigging is fastened.
 Chain pulley, a pulley with depressions in the periphery of its wheel, or projections from it, made to fit the links of a chain.
 Chain pumps. See in the Vocabulary.
 Chain rule Arith., a theorem for solving numerical problems by composition of ratios, or compound proportion, by which, when several ratios of equality are given, the consequent of each being the same as the antecedent of the next, the relation between the first antecedent and the last consequent is discovered.
 Chain shot Mil., two cannon balls united by a shot chain, formerly used in naval warfare on account of their destructive effect on a ship's rigging.
 Chain stitch. See in the Vocabulary.
 Chain timber. Arch. See Bond timber, under Bond.
 Chain wales. Naut. Same as Channels.
 Chain wheel. See in the Vocabulary.
 Closed chain, Open chain Chem., terms applied to the chemical structure of compounds whose rational formulæ are written respectively in the form of a closed ring (see Benzene nucleus, under Benzene), or in an open extended form.
 Endless chain, a chain whose ends have been united by a link.


 For·mu·la n.; pl. E. Formulas L. Formulæ
 1. A prescribed or set form; an established rule; a fixed or conventional method in which anything is to be done, arranged, or said.
 2. Eccl. A written confession of faith; a formal statement of foctrines.
 3. Math. A rule or principle expressed in algebraic language; as, the binominal formula.
 4. Med. A prescription or recipe for the preparation of a medicinal compound.
 5. Chem. A symbolic expression (by means of letters, figures, etc.) of the constituents or constitution of a compound.
 Note: ☞ Chemical formulæ consist of the abbreviations of the names of the elements, with a small figure at the lower right hand, to denote the number of atoms of each element contained.
 Empirical formula Chem., an expression which gives the simple proportion of the constituents; as, the empirical formula of acetic acid is C2H4O2.
 Graphic formula, Rational formula Chem., an expression of the constitution, and in a limited sense of the structure, of a compound, by the grouping of its atoms or radicals; as, a rational formula of acetic acid is CH3.(C:O).OH; -- called also structural formula, constitutional formula, etc. See also the formula of Benzene nucleus, under Benzene.
 Molecular formula Chem., a formula indicating the supposed molecular constitution of a compound.

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 benzene nucleus
      n : a closed chain of 6 carbon atoms with hydrogen atoms
          attached [syn: benzene formula, benzene ring, {Kekule
          formula]