INVOICE 183 IODOFORM of the Thirty-nine Articles strongly con- demns the invocation of saints. The practice, as a private devotion, was known in Caroline days, and lingers, in a debased form, in country districts, in the rhyme : "Matthew, Mark, Luke, and John, Guard the bed that I lie on," etc. With the Oxford Movement the doc- trine of the Invocation of Saints came to the front. INVOICE, a statement on paper con- cerning goods sent to a customer for sale or on approval. Details respecting which it is important for the consignee to be informed are added, and in these respects it differs from a trade bill or definite account. INVOLUCRE, or INVOLUCRUM, in botany, verticillate bracts surrounding the flowers of Umbelliferx and Com- posite. Those surrounding the general umbel in the former order are called the universal involucre, and those around the umbrellules the partial involucre. An involucre may be caliculated, scaly, imbricated, superimposed, etc. INVOLUTION, in mathematics, the operation of finding any power of a given quantity, the multiplication of a number into itself any given number of times; thus the third power of 2 is found by involution, or multiplication of the num- (ber by itself, and the product by the same number; thus 2X2X2 = 8. It is the reverse of Evolution (q. v.). The operation of involution may be directly performed by continued multiplication, but it is often performed by means of formulas, particularly by the binomial formula. In grammar, the insertion of one or more clauses or members of a sentence between the agent or subject and the verb. In pathology, the restoration to its normal size of any part which has been abnormally developed. The opposite of evolution. 10 (i'6), in Greek mythology, accord- ing to one of the most popular versions, a daughter of Inachus, King of Argos. The love of Zeus for this maiden roused, as in other myths, the jealousy of Hera, who transformed lo into a heifer, and placed her in charge of Argus Panoptes. This guardian was slain by Hermes, who was thence called Argeiphontes, or the Slayer of Argus. Hera then sent a gad- fly, which stung the heifer, and drove her in madness over the earth. Thus began those wanderings of lo which iEschylus has sketched in his drama of "Prometheus Chained." 10, in astronomy, (1) the first satellite of Jupiter, discovered by Galileo in 1610. The names of the four satellites of this planet are seldom used, especially as three of them have been assigned to aste- roids as well, and they are generally known by the numbers I, II, III. and IV. (2) The name of the 8.5th asteroid, dis- covered by Peters at Clinton, N. Y., Sept. 19, 1865, the fourth of the small planets detected by him. IODIC ACID, HIO3, white, crystalline solid, formed when iodine is boiled with strong nitric acid, or when sulphuric acid is added to a solution of barium iodate. Specific gravity 4-629, m.p. 110° C. Sol- uble in water, and easily decomposed by reducing agents, forming hydriodic acid and free iodine. Used in medicine as a caustic for external application. IODINE, in chemistry, a haloid mona- tomic element; symbol I; at. w. 127. Obtained from the ash of sea- weeds called kelp. In pharmacy, iodine is used externally in chronic skin diseases and over en- larged and indurated parts and diseased joints to alter action or cause absorption, or to kill parasites. It may be applied in the form of a liniment, a solution, a tincture or an ointment. The vapor iodi (vapor of iodine) may be used as an inhalation in some forms of chronic bronchitis and phthisis. A solution of iodine is useful for rendering very trans- parent objects more distinct. lODISM, the term within which is included a variety of painful and incon- venient results following, under rare cir- cumstances, the administration of iodine and its salts, but more especially the iodide of potash ; mental depression ; irri- tation of mucous membranes, as sneez- ing, watering at the eyes, etc.; a papu- lar and postular eruption of the skin; nausea, loss of appetite, and a bitter taste in the mouth. IODOFORM, in chemistry, CHI3, a lemon-yellow crystalline substance, hav- ing a safFron-like odor and an unpleasant iodine-like taste. Its odor is most per- sistent, and can hardly be removed. It is of interest as having a composition similar to that of Chloroform (q. v.), from which it only differs in having iodine in the place of chlorine. It may be prepared by the action of iodine on alcohol in the presence of carbonate of potash. It is employed externally as an application to painful ulcers, and it often gives relief in uterine cancer. In the form of iodoform gauze it is used in antiseptic surgery.
