Ion to Ivory black

to Isin glass
of seaweeds. Used medicinalIy, both internaIly and externally, and in dyestuffs.
Ion. (Abbreviation of ionic) (Chern.) Pertaining to the theroy of electro­lytic dissociation; i.e., the molecules of all acids, bases, and salts disso-ciate in varying degrees when dis-solving in water or certain other solvents. (Phys.) An. atom which has lost one or more of its electron.., and left with a positive electrical charge.
Ion bum. (Tel.) A discolouration of the center of the fluorescent screen of a cathode-ray tube caused by heavy negative ions striking it.
Ionic. (Arch.) Pertaining to that or­der of Greek architecture charac­terized by scroll like ornaments of the capital. (Print.) Name given to a particular type face.
Ionic order. The style of architec­ture developed .by the Ionians. Its columns are fluted and surmounted by a capital in which scroIls form an important feature of declaration.
Ionization. (Chern.) The breaking up of a compound, as an electroyte. into positive and negative ions.
Ion trap. (Tel.) A device used in eliminating the ion burn on the end of the picture tube.
Iridescence. (Phys.) A multicoloured appearance.
Iridium. A silver-white metallic ele­ment of the platinum group.
Iris. (Tel.) Diaphragm of control-table apperture used to control light emission.

Irish moss. Derived from a form of seaweed, which, on boiling with water, forms a jeIly which is used in the textile and leather indus­tries.
Iron. (I) That metalIic element which plays the most important part in the industrial world. It is obtained from ores in combina­tion with other substances. Irons is marketed as cast, wrought, maIleable, and steel. (2) A meas­ure of thickness for leather equal to 1/48 of an inch.
Iron core transformer. (Elec.) A transformer with the coils wound around an iron core for greater magnetic coupling of the coils.
Iron-oxide paint. Made from an iron-oxide earth and prepared for use by mixing with linseed oil. It is used as a proteCtive coating for metals.
Iron-work. (Arch.) Iron used for or­namental purposes. In the archi­tecture of the Middle Ages very elaborately designed ornamenta­tion in ironwork was used for hinges, knockers, escutcheons, etc.
Irregular. Departing from or being out of the usual or proper form, or order.
Irregular curve. (Draft;) A drafts­man's tool used for drawing curves which are not arcs of circles. Also called French curve or universal curve.
Irregular polygon. Polygon in which the sides are of unequal length, hence the angles are unequal.
Isin glass. (I) A semi-transparent substance made from the air blad­

Isocyanate resin to Ivory black

ders of fishes; used in jellies and glue. (2) A transparent mica. SEE Mica.
Isocyanate resin. (Plast.) The readi­ness of isocyanates to combine with active hydrogen atoms has opened the way for a new field of techno­logy in the plastic industry known as urethane chemistry, the field of flexible and rigid foams. Not only have the properties and techniques improved, but urethane is now foamed-in-place, and made in molds to any need and shape.
Isogonic lines. (Surv.) Those lines drawn on a map connecting all places where the declinatioin of the needle is the same at a given time.
Isolating switch. (Elec.) A switch used for isolating a circuit from its source of power; to be operated only when the circuit has been opened by some other means.
Isometric. A form of perspective draw­ing accomplished without reference to vanishing points. Lines which are parallel on the object appear parallel on the drawing.
Isopropyl alcohol. (Chern.) Rubbing alcohol.
Isosceles. (Math.) Having two sides of equal length, as an isosceles triangle.
Isosceles triangle. A triangle having two sides equal.
Isosotope. (Chern.) Two nuclei of the same element which have the same charge but differnt masses, i.e., having the same number of protrons but a different number of neutrons.
Italic. (Print.) Slop~ng letters; fre­quently used for important refer­ence notes or for some item to which particular attention is called.
Ivory. (Furn.) The tusks of certain animals used for inlay and other decorative work.
Ivory black. (Wood Fin.) A staining material made from charred bone; also a paint.

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