The first attempt was made with plate glass. In order to bring the glass and copper into more intimate union, the first was reduced to powder, and the other was used in the form of filings. The metal was used in the proportion of 3 parts to 100 parts of glass this mixture was brought to a state of complete fusion before the glass was poured out. No success attended this experiment, the glass appearing uncoloured, and the copper remaining mixed with it mechanically in the form of metallic globules.

The next trial was made with common white glass, mixed with twice the proportional weight of copper filings that had been employed in the first experiment. The compound having been completely melted, was found to have assumed a red colour, which was uniformly diffused throughout the mass; but this colour was so deep as to render the glass nearly opaque.

A trial made with copper, already in the form of an oxide, imparted a greenish colour to the glass.

It is impossible not to remark that the circumstances under which these experiments were conducted, as detailed by M. Guyton-Morveau, differ in some essential particulars from those which accompanied the accident by which they were suggested. In that case, the glass was already in the state of fusion, and probably also in a high state of incandescence before the addition of the copper. The proportion of metal used in the second experiment was evidently excessive; and it is surprising that the effect produced did not lead M. Guyton-Morveau to try the effect of a smaller proportion.

Attempts have been made to colour glass by subjecting it to the action of heat, while surrounded by some cementing substances already impregnated with metallic oxides as colouring ingredients. In most of these cases the glass remained perfectly colourless, unless the heat had been carried sufficiently far to induce devitrification; which state, as it renders the material opaque, furnishes sufficient objection to the use of this method of colouring. Even in those cases where transparency is not required,

the same effect can be attained by easier means, and free from a very serious inconvenience, that of the adhesion of the cementing substance to the glass. Some curious facts connected with this subject will be detailed in the concluding chapter of this volume, which treats of the devitrification of glass.

CHAP. XIV.

ON THE ART OF STAINING AND PAINTING GLASS,

THIS ART MORE RECENT THAN THAT OF COLOURING. ENCOU RAGED BY THE MONKS. EARLY SPECIMEN AT ST. DENIS. ART NEVER MUCH CULTIVATED IN ENGLAND. - SPLENDID PAINTINGS AT GOUDA. — DIRECTIONS GIVEN BY OLD AUTHORS FOR COMPOSING COLOURS. FLUXES. VEHICLES FOR DILUTING COLOURS.- DESCRIPTION OF VARIOUS STAINS. METHOD OF FLOATING THESE. - OF PAINTING ON GLASS. IMITATION OF GROUND GLASS WITH TRANSPARENT PATTERNS.DESCRIPTION OF KILN EMPLOYED. -METHOD OF FIRING.SECOND AND THIRD FIRING. ANCIENT METHOD OF FIXING DIFFERENT COLOURED GLASSES ON EACH OTHER.

THE invention of the art of painting on and staining glass, although probably recent as compared with that of colouring the body of the metal when in fusion, is yet known to have existed for many centuries.

The exact period of its adoption is, indeed, involved in much obscurity; and it can, at best, be regarded as only a reasonable conjecture, which assigns its principal excellence, if not its origin, to the fostering care of those religious communities which, upon the breaking up of the great western empire of Rome, became, and for so long a period thereafter continued, the sole depositaries of learning and the arts in Europe.

Endowed by the piety or superstition of their unenlightened followers with revenues far beyond their personal wants, the clergy of that time expended a portion of their superfluous wealth in the construction of those splendid temples which attest to the present day the architectural skill and genius of their founders, remaining unsurpassed and almost unrivalled in their kind as objects of admiration through a great portion of Europe. The ministers of a religion which addressed itself to the imaginations and the feelings of its votaries, they could not, perhaps, have adopted more effectual means for

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obtaining and perpetuating their influence over the multitude. Some idea of the extent to which these means must have operated may be formed by every one who recalls to mind the sensations of solemnity amounting to awe wherewith he has himself been struck as he has stood beneath the lofty sculptured arches of a cathedral, or walked through its lengthened aisles, radiant with tints glowing through emblazoned windows.

The earliest specimens of these embellishments differ from those of more recent date in having been formed of small pieces of glass coloured throughout during the process of its original manufacture, and which, to distinguish it from glass coloured or stained by the methods that will be hereafter described, has been called by artists pot metal. Pieces of this, cut to the shapes required, were joined together in the manner of mosaic by the interposition of lead, in a way which has since fallen greatly into disuse; the method of staining and burning in metallic colours on the surface of the glass having been found far more beautiful, admitting of greater variety of tints, as well as of those delicate shadings which were manifestly unattainable by even the most laborious composition in mosaic work.

Perhaps the oldest existing specimen of this later-discovered art of painting on glass is to be seen on the windows of the abbey of St. Denis, whereon were recorded, in 1194, various events which occurred during the first crusade.

This art has never flourished to any great degree in England, where at no time have men of genius been much encouraged to apply their talents to its advancement many among the most admired specimens of painted glass which ornament our religious edifices, are the productions of foreign artists.

The great church at Gouda, in Holland, is splendidly embellished with painted windows, which, about the year 1555, were executed by various artists, the most celebrated among whom were Dirk and Walter Crabeth. The one among the windows which is the most highly

esteemed was painted by the first mentioned of these two brothers; and Mr. Hollis mentions, as evidence of the value placed upon this work of art, that for the lower part of this window, - about twenty feet square,- Mr. Trevor, some time English resident at the Hague, had in vain offered to give a solid plate of gold of the same surface, and of the thickness of three Dutch guilders.

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This particular division of the fine arts differs from other branches in containing within itself fewer incentives to its prosecution. Its practice is accompanied by various laborious and differing processes. The range of subjects which it admits is far more circumscribed, and the opportunities which it offers for the display of excellence are far less frequent. The artist is even without the gratification of witnessing the satisfactory progress of his own work, the appearance of which is comparatively dull and uninteresting until after it has passed from his own hands into those of "red Lemnos' artisan." The sculptor and the painter in oil colours can seldom fail in procuring means for exhibiting their works; so that, according to the degree of talent evinced by them will generally be their encouragement and reward; while the man who has conquered every disadvantage attending the processes of staining glass, and who may have produced a piece, the conception and execution of which are alike honourable to his genius and assiduity, might look in vain for the opportunity of bringing its merits before the world. These works have, therefore, seldom if ever been undertaken, unless at the requirement of others, who, dictating both the subject and its details according to their own peculiar tastes and wishes, leave nothing wherein the superior talents of the artist can be displayed, save the correctness of drawing and the elaborateness of execution. A man of genius will not consent to be thus trammelled, or follow, for the attainment of a precarious recompence, one profession, when, by bringing to the exercise of another the same amount of talent, and far less labour, he may at once give scope to his conceptions and advance his worldly interests.