GLASS MANUFACTURE. 



cI.ASSTAINTINa. 



ingredients for the glass. Sometime* them are put into the melting- 

 pot, to nuke the glass equally coloured throughout iU substance ; 

 sometime* coloured layer U applied to a culourleM substratum. An 

 example of this lait-named kind hu been noticed in a former para- 

 graph, concerning cut flint-glass Teasels exhibiting a gradation of tints; 

 and flat pane* of glass are produced in an analogous way, by collecting 

 colourless glass on the end of a tube, dipping it into coloured glass, 

 and then flashing it out into crown or sheet glass. So far aa concerns 

 the actual manufacture of coloured glass, the ingredients are nearly or 

 quite the name, whether it be surface-colour or through-colour. \\ hat 

 14 called stained or, more properly, painted glass, however, is generally 

 understood to be something in which the artist is more concerned 

 than the manufacturer. It is a kind of enamel painting, or enamelling, 

 and it effected in the way described in the next article. [GLASS 

 PAINTIXO.J 



Soluble or \\'atrr Gtatt. We may here add a few words concerning 

 soluble glass, which is at present exciting some attention. It IB a 

 chemical agent rather than a manufactured product; still, it is a 

 vitreous substance as soon as it has solidified. About the year 1825, 

 Dr. Johann Fuchs, of N urn berg, commenced a course of experiments 

 n the production of a liquid glass, produced by a fusion of silica 

 with potash and soda. From time to time the subject came under 

 public notice, but not with any definite result until recently. In the 

 spring of 1859, at the request of the Prince Consort, Dr. Fuchs gave a 

 summary of all that he had done, in a paper read before the Society 

 of Arts. He made many varieties of the liquid glass, some with soda, 

 some with potash, and some with both iilkalies, combined in a particular 

 way with crushed quartz or quartzose sand. He had been struck with 

 the possible value of these silicates as a varnish, which, hardening into 

 a glass, would preserve the surface of stone from decay ; but his chief 

 labours were towards the production of a new vehicle for fresco- 

 painting. Meanwhile, Professor Kuhlmann, of Lille, had been engaged 

 for many years in studying the action of the soluble silicates with the 

 salts of lime ; and in 1857 he made known the results of his method 

 of proceeding, in producing a stone-protecting silicate. An English 

 < jperimentalist, too, Mr. Ransome, was working towards the same end, 

 but by a different path. He devised a mode of making artificial stone, 

 by combining sandy or stony fragments with silicate of soda ; and he 

 also produced a vitreous varnish for the surface of stone, consisting of 

 silicate of calcium instead of silicate of soda. Portions of the Louvre, 

 f the Cathedral of Notre Dame at Paris, of the Houses of Parliament 

 at Westminster, of the Baptist Chapel in Bloomsbury Street, of the 

 Pavilion at Brighton, of the Custom House at Oreenock, and of other 

 buildings, have been coated with one or other of the different kinds of 

 water-glass ; but many controversies have thence arisen, and it remains 

 yet to be proved how far this kind of vitreous coating will be per- 

 manently protective. The causes which bring about that decay of stone 

 implied in all these experiments, are noticed under ATHOSPIIKRIC 

 INFLUENCE. Another kind of soluble glass, intended to protect wood- 

 work from the action of fire, is noticed under FIREPROOFING. 



Glatt Trade. The glass-trade in iU fiscal and commercial relations, 

 presents many instructive features. At an early period of ita history 

 in this country the glass manufacture became an object of taxation, 

 and duties were imposed by the 6 and 7 William and Mary, which 

 acted so injuriously, that in the second year after the act was passed 

 one half of the duties was token off, and in the following year the 

 whole was repealed. In 1746, when the manufacture bad taken firmer 

 root, an excise duty was again imposed, at the rate of one penny per 

 pound on the materials used for making crown, plate, and flint-glass, 

 and of one farthing per pound on those used for making bottles. In 

 1778 these rates were increased 50 percent, upon crown and bottle- 

 glass, and were doubled on flint and plate glass. The rates were 

 further advanced from time to time in common with the duties upon 

 most other objects of taxation, and in 1806 stood as follows : on plate 

 and flint-glass, 4'J. per cwt. ; on crown and German sheet-glass, 86. 9d. 

 per cwt ; on broad glass, 12i. 3d. ; and on common bottle glass, 4. Irf. 

 per cwt. In 1813, those rates were doubled, and with the exception 

 of a modification in 1819 in favour of plate-glass, then reduced to 31. 

 per cwt., were continued at that high rate until 1825. In that year a 

 change was made in the mode of taking the duty on flint-glass, by 

 charging it on the weight of the fluxed materials instead of on the 

 articles when made, a regulation which did not affect the rate of charge. 

 In 1880, the rate on bottles was reduced from 8. 2</. to 7*. per cwt. 

 The next alteration made in these duties occurred in 1835, when, in 

 consequence of a recommendation contained in the thirteenth Report 

 of the Commissioners of Excise Inquiry, the rate upon flint-glass 

 was reduced two-thirds, leaving it at 'id. per pound ; a measure 

 rendered necessary by the encouragement given under the high duty to 

 the illicit manufacture, which was carried on to such an extent as to 

 oblige several regular manufacturers to relinquish the prosecution of 

 their business. Much were the variations in the rate of duty ; and the 

 amount of revenue was equally fluctuating. In 1793, when taxation 

 was comparatively low, the quantity of all kinds of glass made and 

 retained for use in the kingdom was 407,203 cwt., and the amount of 

 revenue obtained from it 177,4081. The average rate of duty was 

 therefore 8*. 8(4. per cwt. upon the whole quantity. In 1634, the rate 

 of duty had by progressive additions become fourfold what it was in 

 1793, the average being 35*. 7Jrf. per cwt, upon the aggregate quantity 



used ; and although the population had in the mean time increased more 

 than 60 per cent, the quantity of glass which was taken for use was 

 only 374,351 cwt., or one-twelfth less than was so taken in 1793. If the 

 quantity used in proportion to the population had continued the same, 

 that quantity would in 1834 have amounted to 663,740 cwt, and a 

 revenue equal to what was realised would have resulted from an 

 average rate of 20. instead of 35j. 7J-'. 



It was in 1845 that Sir Robert Peel took off the duty on glass. The 

 effect was very marked not so much on account of the actual duty 

 thrown off, as on the removal of the exciseman from the glass-works, 

 where he had hampered the manufacturer in all experimental attempts 

 to improve the quality and cheapen the price of the manufactured article. 

 Immediately before the removal of the duty, there were fourteen 

 manufacturers of crown and sheet-glass in the United Kingdom ; they 

 became at once overwhelmed with work. The makers had neither 

 buildings nor hands enough ; they built new works, and hired workmen 

 from abroad. The Frenchmen who worked at crown glass making 

 could command 51. a-week ; while the makers of sheet glass earned 4/. 

 to 81. a-week. New companies were formed, and capital was thrown 

 into the glass trade from various quarters. As in many similar cases, 

 however, incompetence and recklessness did their work ; the trade was 

 weeded in the course of a few years, and the manufacture (of crown, 

 sheet, and plate) is now in the hands of a small number of very large 

 establishments. The excitement in England had a remarkable effect in 

 Belgium. In the glass factories of that country, the workmen are 

 engaged, not for a definite period, but for the " life of the furnace," as 

 it is called, that is, as long as the furnace remains heated. The manu- 

 facturers, at the period in question, maintained the " life " of their 

 furnaces as long as possible, to prevent their workmen from migrating 

 to England, or from demanding higher wages. All these matters 

 gradually found their proper level ; and the gloss trade is now extensive 

 and steady in England, without being disturbed by convulsive changes. 



The glass-trade, as far as concerns exports and imports, is not one of 

 distinguished magnitude. The English factories are able to supply 

 most of the home demand ; while they are not well able to command 

 a large export trade. 



GLASS-PAINTING. The terms Painted Glass and Stained Glass 

 are often used, and even by writers on glass-painting, as though they 

 were synonymous. But there is a broad distinction between the two. 

 Stained glass, is glass the substance of which has been stained or 

 coloured in the process of manufacture. [GLASS MANUFACTURE.] 

 Painted glass, is glass which, whether previously stained or colourless 

 has had a design painted upon it with colours, usually metallic oxides, 

 combined with a vitreous vehicle, or flux ; and which colours, on being 

 subjected to a powerful heat, liave become permanently united with 

 the surface of the glass. Windows formed wholly of one or other of 

 these kinds of glass would be strictly either stained or painted glass 

 windows, as the case might be. In mediaeval examples, however, 

 what are called painted glass windows are usually formed of a combi- 

 nation of stained and painted glass. 



The art of making coloured gloss was known to the Egyptians and 

 Assyrians, and from them passed to the Greeks and Romans. That 

 glass was used for windows by the Romans is certain from more than 

 one passage in Latin authors, and from specimens of window-glass 

 having been found both at Pompeii and Herculaueum. It is not 

 known, however, though it is not improbable, that they glazed their 

 windows with stained glass ; but stained glass windows must have 

 been in use at a comparatively early period in Byzantium. Byzantine- 

 Greeks appear also to hove been the first practitioners of painting on 

 glass; and it is conjectured, with reason, that the practice of glazing 

 with coloured glass in ornamental patterns, and the art of painting on 

 glass, were both introduced into Western Europe from Byzantium, by 

 way of Venice and Marseilles. The practice of glazing windows with 

 stained glass arranged in patterns was imitated from the Byzantine- 

 Greeks by the Saracenic races, and has been continued in the cities of 

 the East down to the present time. The earliest reference to the use 

 of stained glass windows in Europe appears to be in a passage of 

 Prudentius (quoted by Labarte, ' Handbook of the Arts of the Middle 

 Ages,' p. 66) about the beginning of the 5th century ; but a more 

 distinct mention of them is mode in the following century. Painted 

 glass windows are not spoken of for two or three centime* I 



The earliest existing examples of painted glass windows which 

 Lasteyrie has been able to discover are in the abbey of Tegernseo, in 

 Bavaria : they were presented to the abbey by Count Arnold hi the 

 year 999. Five other windows in the same abbey, painted by the 

 monk Wcrnhcr, date between 1068-91. At Hildeshcim there are also 

 some which are attributed to one Bruno, and to the years 1029-39. 



The earliest examples in France, the country in which the art of 

 glass-painting was, during its most flourishing period, practised with the 

 greatest success, belong to the 1 2th century : the oldest being a repre- 

 sentation of the Funeral of the Virgin, in Angers Cathedral, of the first 

 half of the century ; the others are some medallion windows of a very 

 remarkable character, placed in St. Denis by the Abb<5 Sugcr in the 

 latter half of the century. 



It was in the latter ]>art of the 12th and the 13th centuries that tho 

 art made its greatest advance. Painted glass windows had now come 

 to be regarded as essential in religious edifices of any pretension. It 

 was the period in Qotbip architecture correspond ing to our Transition. 



