Two propylene glycols, C3H8O2, are known, viz. α-propylene glycol, CH3·CH(OH)·CH2OH, a liquid boiling at 188° to 189°, and obtained by heating glycerin with sodium hydroxide and distilling the mixture; and trimethylene glycol, CH2OH·CH2·CH2OH, a liquid boiling at 214° C. and prepared by boiling trimethylene bromide with potash solution (A. Zander, Ann., 1882, 214, p. 178).
GLYCONIC (from Glycon, a Greek lyric poet), a form of verse, best known in Catullus and Horace (usually in the catalectic variety
), with three feet—a spondee and two dactyls; or four—three trochees and a dactyl, or a dactyl and three chorees. Sir R. Jebb pointed out that the last form might be varied by placing the dactyl second or third, and according to its place this verse was called a First, Second or Third Glyconic.
Cf. J. W. White, in Classical Quarterly (Oct. 1909).
GLYPH (from Gr. γλύφειν, to carve), in architecture, a vertical channel in a frieze (see [Triglyph]).
GLYPTODON (Greek for “fluted-tooth”), a name applied by Sir R. Owen to the typical representative of a group of gigantic, armadillo-like, South American, extinct Edentata, characterized by having the carapace composed of a solid piece (formed by the union of a multitude of bony dermal plates) without any movable rings. The facial portion of the skull is very short; a long process of the maxillary bone descends from the anterior part of the zygomatic arch; and the ascending ramus of the mandible is remarkably high. The teeth, 8⁄8 in the later species, are much alike, having two deep grooves or flutings on each side, so as to divide them into three distinct lobes (fig.). They are very tall and grew throughout life. The vertebral column is almost entirely welded into a solid tube, but there is a complex joint at the base of the neck, to allow the head being retracted within the carapace. The limbs are very strong, and the feet short and broad, resembling externally those of an elephant or tortoise.