GLAUBER'S SALT. 



GLAZING. 



only in hi* subsequent procune* modifying by ihadowi or superficial 

 tint, the origin*! ..-h niece of glass it separately painted, 



Djkltxl, or diapered, and then Area ; the laying on of the colour* and 

 the firing being repeated a* often a* neeemry. When the painting U 

 completed the piece* are fixed in their leaden frame- work ; this is (up- 

 ported by an arming of iron laddlo-bar*, and the whole i placed in itt 

 proper position in the building. 



In glaa* pinttng the artint ha* many difficultiw to Mimmunt ; and 

 he can only hope to mrmount tlirni liy a clenr oomprehension of the 

 special requirement* of hi* art. and the Adoption of a (pacific ctyle of 

 treatment. Hi* work in *o placed tunially that it can only be looked 

 a* from a distance. Being a window, his pointing murt not obscure 

 but only modify the light He may graduate hi- tints, l.ut. when in 

 position, not only do his more delicato gridations disappear, I" 

 the half-tint* are lost. In the countenances, refinement* of expression 

 are commonly valueles*. The transparency of the medium at once 

 refute* any close imitation of solidity in the object*. Hence the 

 attempt* to copy pictorial effect* are always unsatisfactory. There U 

 little chance of success except by unreservedly accepting the con- 

 rationalities of the art, and treating the window as a window, an. 1 not 

 M a portion of wall-snrfaoe. The subject must be conventionally 

 rendered, but not necessarily, tin rrfrv. archaically ; there is no reason 

 why the forms, costumes, and composition should not be .11 perfect as 

 the artist can make them. In the colouring of the parts as well as of 

 the whole, the most gem-like richness and brilliancy must be aimed 

 after ; and the window be rendered at once harmonious in itself, and in 

 harmony with the other windows, as well as with the building of which 

 it is a portion. 



The following works may be consulted on the history of painting on 

 glass : they will supply any further references the student may require, 

 Lasteyrie, ' HUtoire de la Peinture frar Verre d'apres des Monumens 

 en France,' 2 vols. fol., Paris, 1888-56, a very splendid and erudite 

 work, in which representations in chromo-lithography arc given of the 

 best French examples from the 12th to the 18th century. With it 

 may be compared a ' History of Stained Glass from the earliest period 

 of the art to the present time," by W. \Varrington, 1 vol. fol., 1848, 

 which in a measure does for English glass painting what the work of 

 M . Lasteyrie does for that of France ; but unfortunately the series of 

 chroino-lithographic designs (illustrating the changes of style from the 

 18th to the 16th century) are not copies of old windows, but of windows 

 painted by the author himself in imitation of old ones : many ancient 

 English as well as German and Flemish examples, however, are supplied 

 in WeaJe's ' Divers Works of Early Masters in Christian Decoration,' 

 2 Tols. folio., 1846-7. In Mr. .). 1). Waring'* 'Arts connected with 

 Architecture, ftc.,' fol. 1858, is given a series of examples executed in 

 coloured lithography, by Mr. V. Brooks, of stained glass windows 

 in Central Italy, from the 13th to the 15th century. Gessert, 

 ' Geschichte der Glasmalerei in Deutachland, und Niederlanden, 

 Fnnkreich, England, der Schweitz, Italien, und Sptmien, von ihrem 

 Ursprung bisauf die neueste Zei,' 8vo., Stuttgart, 1839. On the 

 theory and practice of the art, see ' An Enquiry into the Difference 

 of Style observable in Ancient Glass Painting, especially in England, 

 with Hint* on Glass Painting, by an Amateur' (Chas. Winston), 

 2 vota. 8ro., Oxford, 1847 ; and ' An Introduction to the Study 

 of Painted Glass,' by the same author, 8vo., Oxford, 1849; V. \V. 

 Oliphant, ' A Plea for .Painted Glass,' 8vo., Oxford, 1855 ; Langloit, 

 ' Enai sur lu Peinture sur Verre ;' P. Lc Vieil, ' L'Art de la Peinture 

 sur Verre et de Vitrie ; ' G. Bontemps, ' Peinture sur Verre au dixneu- 

 vieme siecle, 1 Par., 1845 ; E. 0. Fromberg, ' Handbueh der Glasma- 

 lerei,' Lei pi., 1851, translated into English under the title of 'An 

 Essay on the Art of Painting on Glass, 12mo., 18M ; M. A. Gessert, 

 ' Die Runit auf GUs zu Malen,' translated into English under the title 

 of ' A Rudimentary Treatise on the Art of Painting on Glass,' 12mo., 

 1851 ; Sir (}. Wilkinson, ' On Colour,' pp. 23-55 ; and for the 

 Italian method of glass painting, ' Original Treatises dating from the 

 12th to 18th centuries on the Arts of Paintlng.'edited by Mrs. Merri- 

 fteld, vol. L, chap, ivr 



There in a kind of ornamental window-glass called Mntii,l W<irl; in 

 which the glass 1s covered with a very fusible compoxition, .-itln r 

 white or tinted, previously reduced to an impalp.il.].- ponder. This 

 composition i* then removed from certain parts of the glass, a. 

 to the required pattern, and, after firing, produce* on tlie gl.i 

 ((round with a bright pattern. The demand for ornamental glass 

 having increased lately, several persons have attempted, some by 

 tenctlling, others by the application of machinery, to produce it at a 

 cheap rate ; and matted work can now be obtained at one-fourth <f the 

 price that would have been charged a few yean since. 



Another tnr-th'xl of ornamenting glass, rather inappropriately termed 

 rmbtttiny, connisut of a bright figure on a dull ground. The part* 

 intended to be dull ore painted ovi-r with varnish ; hydrofluoric acid i* 

 then poor.-d on, which ct.-he, the glass to a certain depth. After the 

 acid and varniih are washed off, the glass i* ground by nil.l.ing with 

 another piece of flat glus and fine emery. This procem removes 

 the original nurface of the glow, and produces the dull ground ; and 

 the design, having been sunken by the action of the add, is untouched 

 in the grinding process, and left bright. 

 OLAUBER r S SALT. [Souirv, A'oc/<i, i,,l,Aate </.] 

 OLAUCINE, an alkaloid found in the leaves and (terns of Glanclnm 



lte*m. It forms salt* with the acids, and has a bitter acrid taste. It 

 oooun in the form of pearly scales. OUuteapierint, found in the name 

 plant, differ* from the above compound. The composition of both is 

 !..ut.tfuL 



(il.UTCOMA (from yuwmli, blue or bluish-gray), a disease of the 

 eye, characterised by the pupil losing it* naturally black colour, and 

 presenting a clear or dull greenish hue. It was first described by 

 Bruseau, partly from observation* made in the po*t-mortem exami- 

 nation of the eyes of Bourdelot, physician to L.m- \ I V It seems to 

 wentially on disease of the choroid membrane and retina | KTF, 

 in NAT. HUT. Div.], generally combined with morbid alteration in the 

 vitreous humour and hyaloid membrane, and in the lens and its capsule. 



The symptoms by which it is indicated are ]>ain in the hc.-\<l 

 the brow, or across the forehead, weakness of night, and a ^. 

 colour of thv pupil, mo*t intense when one looks directly down, into 

 the bottom of the eye, where it seems almost as if there lay a piece of 

 shining metal The pupil is rather dilated, and the motions of flu- 

 ids are slow. A the disease advances, the greenish colour become* 

 more marked, vision more and more indistinct, and at lost, when it i* 

 entirely lost, the iris is quite motionless. Frequently the disease 

 spread* to the lens, producing a glaucornatous cataract [CATARACT], 

 and sometimes is accompanied with evident Inflammation of the super- 

 ficial parts of the globe. 



The disease seems to Consist in chronic inflammation of the deep- 

 seated part* of the eye. Those of a gouty con- dally 

 those who have lived freely, and have passed tl t' life, 

 as well as persons of scrofulous constitution, or who are employed in 

 very delicate work, are the most frequent subjects of it. It is also 

 more frequent in some countries and classes than others. Scarpa 

 never met with a case of fluidity of the vitreous humour during hU 

 long practice at Pavia ; while in Kngland such a condition Is by no 

 means rare in old persons. Benedict Kays that he found glaucoma very 

 lent among the Jews in Breslau. 



On examination of the eyes thus affected, the choroid membrane is 

 found to have lost its black colour from the absence of pigment uni 

 nigrum ; it U become dull-brownish, and its vessels are often varicose ; 

 the vitreous humour is generally quite fluid, without a trace of hyaloid * 

 membrane, of a yellowish hue, or with small brownish-green or green 

 spots scattered through it; the retina, is often darker than natu: 

 marked with reddish or black points; the lens in part of a yell 

 or deep amber colour, firm and transparent, sometimes pushed forward, 

 so that the iris is in contact with the cornea. 



The only diseases with which glaucoma can easily be confounded 

 are cataract and gutta serena : it may be distinguished by its history; 

 by the greenish colour of the pupil, which evidently arises from change* 

 of structure in the parts behind it, and which is not visible 

 viewed laterally ; by the defect of vision being disproportionate to the 

 change of colour of the pupil ; and by the sight being best in a strong 

 light. 



Early treatment is necessary, and it should be actively antiphlogistic ; 

 blood should be drawn from the temples, and purgative*, mercury, and 

 abstemiousness be ordered. These, if they do not put a stop to the 

 disease, will retard iU progress, and relieve many of Its symptoms, as 

 the headache, ftc. If, however, the pupil becomes quite green and the 

 iris motionless, the case may be regarded as hopeless ; for there are no 

 means known by which the changes on which these symptoms depend 

 can be removed. 



(Beer, Lthrt ran den Auffenlranthfiteii ; Lawrence, On the IKieata 

 (if the Em; Mackenzie, On the Ditto** of tkt Eyt.) 



GLA&COM ! : I . A N 1 1 ' ACID (C..H.O., HO?), an acid aaid to be formed 

 when an alkaline solution of ellagic acid is exposed to the air. 



GLAUCOPICRINE. [OukVcWK.] 



GLAZING. This name is given to several different processes inHhe 

 manufacturing arts, each of which calls for a brief notice. 



1 . Window Otaanij.'This is the art of fixing glass in the frai. 

 windows, 4e. Putty, with which the glass is usually fixed, consists of 

 whiting and linseed oil. As to the mode of cutting the glass, see 

 DIAMOND. The defective state of most skylights, hothon- 

 shows that the art of glazing them is very imperfectly understood by 

 those who practise it. Wlu-n a skylight is glazed in the ordinary 

 manner, the laps or horizontal joinings fill with \V.I!<T l.\ capillary 

 attraction whenever it rains, aim tin- wind drive* the water into the 

 house. This process goes on as long as the shower lash. S.>m 

 vegetable fibre* hang down from the laps, and, acting ax siphons, draw 

 off the water taken up by them, which then falls into the house, and 

 by iU dropping injures tender plants, &c. The retained wa' 

 expands in freezing, and fractures the glass. 



The following remarks are the result of long practical 

 and careful observation. The edges of the glass whi. 1 ' ' '" 



laps should not be cut straight, but circular; this will add to the 

 beauty of the work, and cause the water to run down the c ntn- of the 

 openings, and not act so much on the bars. The cutting of glaiw in 

 this manner for domes and other ornamental ro..f-. win- the spaces 

 between the bars ore not parallel, was formerly difficult to execute, 

 and expensive on account of the waste of glass; but l>y a contrivance 

 invented a few years ago, this may now be accomplished with ease, 

 ex|>edition, and economy. The laps should be lew than a ,|uarter of 

 nn inch wide, and wholly filled with a cement composed of putty with 



