GLA 



GLO 



bladders of the epidermis ; lenticular, 

 when they exist as brown oval spots upon 

 the bark; internal, when of the nature 

 of cysts or nuclei situated below the 

 cuticle; &c. The disk, or fleshy body 

 which surrounds the base of the ovary 

 in certain plants, is commonly called a 

 hypogynous gland. 



GLANS. In Botany, a compound in- 

 ferior fruit, with a dry pericarp, one- 

 celled, but proceeding from an ovary 

 which contains several cells, and seated 

 in a persistent involucre called a cupule. 

 The gland is solitary in the oak ; in the 

 beech and the sweet chestnut there are 

 several, completely enclosed in the cu- 

 pule. The gland is termed calybio by 

 Mirbel, and nucula by Desvaux. 



GLASS. The varieties of glass derive 

 their vitreous character from the silicates 

 of potash and soda. Crreen or bottle- 

 glass consists of the silicates of alumina, 

 of the oxides of iron, magnesia, and 

 potash or soda. Flint-glass is a silicate 

 of potash and lead. Window-glass is 

 a silicate of soda and lime. Plate-glass 

 ■used for mirrors, crown-glass, and the 

 beautiful Bohemian glass, are silicates of 

 potash and lime. 



The term glass is also applied to glassy 

 substances, as the glass of antimony, or 

 the sulphuret; Muscovy glass, or mica; 

 tin glass, or bismuth, &c. 



GLASS-GALL. Sandiver. The salt 

 scum which floats on the surface of fused 

 glass. 



GLAUBER'S SALT. Native sulphate 

 of soda, occurring together with rock 

 salt and Epsom salt, on the borders of 

 salt lakes, and dissolved in the waters of 

 lakes and of the ocean, &c. Glauber's 

 secret sal ammoniac is a sulphate of am- 

 monia, a constituent of soot from coal. 



GLAU'BERITE. A crystallized salt, 

 consisting of nearly equal parts of the 

 sulphates of lime and of soda, and found 

 imbedded in rock salt brought from 

 South America and from Spain. 



GLAUCIC ACID {'^XavKb^, blue, sea- 

 green). An acid procured from the teazle 

 and scabious plants. 



GLAU'COLITE {-^XavKoi, blue, X/^op, 

 a stone). A bluish-green mineral, found 

 near lake Baikal in Siberia, and consist- 

 ing of a silicate of alumina and lime. 



GLAU'CONIE (yAauKo?, blue, sea- 

 green). A French term applied by 

 Brongniart to some stratified deposits 

 associated with chalk, which correspond 

 with the green sands of English geo- 

 logists. 



152 



GLI'ADINE (7X/a, glue). Vegetable 

 albumen ; one of the constituents of 

 gluten. See Zymome. 



GLIMMER. A name occasionally 

 applied to micaceous earths. 



GLIRES {glis, a dormouse). The 

 fourth order of the Mammalia in the 

 Systema Nalum of Linnaeus, comprising 

 the porcupines, hares, beavers, mice, 

 squirrels, bats, &c., characterized by the 

 presence of two long chisel-shaped in- 

 cisors in each jaw. See Rodentia. 



GLOBE {globus, a ball). A round or 

 spherical body, bounded by one uniform 

 convex surface, every point of which is 

 equally distant from a point within, 

 called the centre. 



1. Artificial Globes are instruments 

 employed for conveying the first ideas of 

 the figure and rotation of the earth, of 

 latitude and longitude, and of the situa- 

 tion of places with respect to each other 

 and to the sun at the different seasons of 

 the year. They are formed of metal or 

 plaster, on the surface of which is de- 

 lineated a map of the earth, or of the 

 celestial constellations, together with the 

 principal circles of the sphere ; in the 

 former case the instrument is called a 

 terrestrial, in the latter a celestial globe. 

 These globes are also used for the pur- 

 pose of solving mechanically a few ele- 

 mentary problems of Astronomy, relative 

 to the difference of the hour of the day at 

 different places, the times of the rising 

 and setting of the sun, the limits of the 

 visibility of eclipses, &c. 



2. Perennial Globe. A contrivance in 

 which there is a motion of the stars 

 about the pole of the ecliptic, and also 

 one about the pole of the equator, so that 

 all the diurnal phenomena can be repre- 

 sented for any epoch, however distant 

 from our own, past or future. 



GLOBULAR CHART. A delineation 

 of the terrestrial surface, or of any part of 

 it, on a plane, according to the principles 

 of globular projection. See Projection. 



GLOBULAR MASSES. Nodules. The 

 geological term for rocks of irregular 

 form, varying from a foot to a mile or 

 more, and imbedded either in a stratified 

 or a massive rock. 



GLOBULAR SAILING. In Naviga- 

 tion, the sailing from one place to an- 

 other over an arc of a great circle, or 

 the shortest distance between the two 

 places. 



GLO'BULINE. The name given by 

 Turpin to the amylaceous granules found 

 in the cells of plants. He considers 



