GLA 



GLA 



instantly established, and to this place it 

 was for a long time confined. Glass was 

 undoubtedly made in great perfection 

 among the ancients. In their accounts, 

 we read of drinking-glasses, glass prisms, 

 and coloured glasses of various kinds. 

 Glass was first used for windows in the od 

 century of the Christian acra, but it did 

 not come into common use till very long 

 after this. 



GLASS, painting on. See ENAMELLING. 



GLASS, in sea affairs, the usual appella- 

 tion for a telescope. A night-glass is a 

 telescope made for viewing objects at 

 night. Half-hour glass, called also the 

 watch-glass, is used to measure the time 

 which each watch has to stay upon deck. 

 Half and quarter-minute glasses are used 

 to ascertain the rate of the ship's veloci- 

 ty, measured by the log ; these glasses 

 should be frequently compared with a 

 good stop-watch, to determine exactly 

 how many seconds they run. 



GLAUBER (JOHN RUDOLPH,) an in- 

 dustrious chemist, was born in Germany. 

 After passing a considerable time in 

 travel, he settled at Amsterdam, about 

 the middle of the seventeenth century. 

 He wrote a number of works, mostly in- 

 fected with the enigmatical jargon and 

 unintelligible theory of the hermetic phi- 

 losophy, yet containing some useful facts 

 in true chemistry, and some processes of 

 his own invention. His name is perpe- 

 tuated in the purgative neutral salt called 

 Glauber's, composed of the sulphuric acid 

 and soda ; a valuable remedy, but, toge- 

 ther with others of his invention, extolled 

 by himself to an extravagant degree. 

 He kept several of his medicines secret, 

 and made advantage of them as nostrums. 

 Of his works an abridged collection was 

 made in German, which was translated 

 into English in 1689; but they are now 

 consigned to oblivion. 



GLAUBER'S salt. See SODA, Sulphate of. 

 It is found native ; and, according to 

 Bergman, it contains sulphuric acid, soda, 

 and water, in the proportions of 27.15.58 ; 

 that is, when saturated with water of 

 crystallization. When efflorescent, the 

 native Glauber's salt contains, beside 

 pure sulphate of soda, some oxide of 

 iron, and portions of muriate and carbon- 

 ate of soda. It is found in old salt mines, 

 on the borders of the salt lakes in differ- 

 ent parts of the world, and on the surface 

 of peat-mosses in France. It is also held 

 in solution in the Natron lakes of Egypt, 

 and the mineral springs of Carlsbad. 

 Glauber's salt easily dissolves in water, 

 and shoots into long and beautiful crys- 



tals, which contain a large quantity of 

 water ; in consequence of which they 

 undergo the aqueous fusion, when ex- 

 posed to heat. This salt, on account of 

 its efficacy as a purgative, was formerly 

 held in the highest esteem, and was de- 

 nominated sal mirabile Glauberi. It has 

 been used in some countries as a substi- 

 tute for soda, in the manufacture of white 

 glass. 



GLAUCOPIS, or the -wattle-bird, in na- 

 tural history,a genus of birds of the order 

 Pics. Generic character : bill incurvate 

 and arched ; lower mandible shorter than 

 the upper, and carunculate beneath at 

 the base ; nostrils depressed, half cover- 

 ed with a cartilaginous membrane; tongue 

 cartilaginous, split, and ciliated at the 

 end; legs carinated at the back; feet 

 formed for walking. 



The G. cinerea, or cinereous wattle- 

 bird, is about the size of a jay ; it is found 

 in every part of New Zealand : berries, 

 and insects of almost every kind, consti- 

 tute its food ; it rarely perches on trees ; 

 but is often seen walking on the ground : 

 its notes are said at different times 

 to resemble whistlings and murmur- 

 ings, and its flesh is good for the 

 table. 



GLAUX, in botany, a genus of the 

 Pentandria Monogynia class and order. 

 Natural order of Calycanthemae. Sali- 

 cariae, Jussieu. Essential character : calyx 

 one-leafed, bell-shaped : corolla none ; 

 capsule one-celled, five-valved, five-seed- 

 ed. There is only one species, viz. G. 

 maritima, sea milk-wort, or black salt- 

 wort. It is common on the sea coast, and 

 on salt marshes at a distance from the sea; 

 it is" a beautiful little plant, enlivening 

 large tracts of the dreary situations where 

 it is found ; the whole plant is succulent, 

 and salt to the taste. It is also a native of 

 the United States. 



GLAZING, in the arts, is the polishing 

 or crusting over earthen ware. When 

 earthen ware is properly baked, it is dip- 

 ped into a composition called a glaze, 

 made by mixing together in water, till it 

 becomes as thick as cream, fifty-six parts 

 of white lead, twelve of ground flints, 

 and three of ground flint glass. The 

 ware, by being baked, acquires a strong 1 

 property of imbibing moisture, and in this 

 state it is called biscuit ; when dipped in- 

 to the glaze, it attracts it into its pores, 

 and the ware becomes presently dry ; it 

 is then exposed a second time to the fire, 

 by which means the glaze it has imbibed is 

 melted, and a thin, glass\ coat is formed up- 

 on the surface. The colour is more or less 



