IRON WIRE. Syn. Ferrum in fila tractum (Ph. L.), Ferri filum (Ph. E.), Ferri fila (Ph. D.), L. This is the only
form of metallic iron retained in the Ph. L. It is used to make preparations of iron.
ISATINE. C16H10N2O4. A yellow crystalline body obtained by the oxidation of indigo. When acted upon by potash it becomes converted into aniline. Isatine may be formed by heating indigo in a dilute solution of dichromate of potash and sulphuric acid, or by treating indigo under proper conditions with nitric acid.
ISCHU′RIA. In pathology, retention, stoppage, or suppression of the urine.
I′′SINGLASS. Syn. Ichthyocolla, L. The finest kinds of isinglass are obtained from various species of the genus Acipenser, or sturgeon, that from the great sturgeon being perhaps the most esteemed. It is the air-bag, swimming bladder, or sound, dried without any other preparation than opening, folding, or twisting it. The picked or cut isinglass of the shops consists of the lamps of staple isinglass picked in shreds by women and children, or cut by machines.
Prop., &c. Good isinglass is the purest natural gelatin known. Its quality is determined by its whiteness, absence of the least fishy odour, and ready and almost entire solubility in boiling water; the solution forming a nearly white, scentless, semi-transparent, solid jelly, when cold. It is soluble in weak acids, and this solution is precipitated by alkalies. The aqueous solution is not precipitated by spirit of the common strengths. 1 part of good isinglass dissolved in 25 parts of hot water forms a rich, tremulous jelly. It is very commonly adulterated. Of the different varieties of isinglass, the Russian is the best and most soluble. See Gelatin.
ISOM′ERISM. In chemistry, identity of composition, with dissimilarity of properties. Isomeric compounds (isomerides) are such as contain the same elements in the same proportions, but which differ from each other in their chemical properties; thus, formate of ethyl and acetate of methyl are isomeric, having precisely the same ultimate composition, though differing in the arrangement of their elements.
ISOMOR′PHISM. In chemistry, the quality possessed by bodies differently composed of assuming the same crystalline form. Isomorphous substances are found to be closely allied in their chemical nature; and the fact of two bodies crystallising in the same form has often led to the discovery of other points of similarity between them. The alums, for instance, no matter what their components, all crystallise in octahedra, and a crystal of potassium-alum, if transferred to a solution of chrome-alum, will continue to increase with perfect regularity from the deposition of the latter salt.
IS′SUE. Syn. Foniculus, L. In surgery, a small artificial ulcer formed on any part of the body by means of caustic or the lancet, and kept open by daily introducing an ISSUE
PEA covered with some digestive or stimulating ointment; the whole being duly secured by an appropriate bandage.