In an English work treating of glass, or rather of certain descriptions of glass, and that chiefly from the artistic point of view, what position in the book and what relative amount of space should be given to the glass of England?

The position is, indeed, readily defined, for our country has but slight claims to recognition as a producer of artistic glass until the commencement of the eighteenth century—indeed we may perhaps say until that century was well advanced. The consideration, then, of the glass of this country must be kept back until that of all the other European States—Italy, France, Spain, Germany, and the Netherlands—that have at one time or another produced glass of artistic importance has been dealt with.

As to the relative importance of our English glass and the amount of space to be allotted to it, this is a question difficult to answer. For a moment, no doubt, towards the end of the eighteenth century, it held the premier place in Europe, on the ground, above all, of the excellence of the material. Advantage was taken of certain exceptional qualities in the English flint or lead glass to produce a deeply cut, facetted ware, solid and brilliant, something undoubtedly sui generis and suitable to its place on the sideboard, or on the well-polished mahogany table when the cloth was removed. The flashing fire of the lights cast back from the skilfully arranged facets of the decanters and glasses, combined with the softer reflections from the silver plate to give an undeniable charm and an individual stamp to these late Georgian dinner-tables. This play of lights has appealed to, and has been not unsuccessfully reproduced by, more than one painter of the present day. But this facetted ware, the one glory of our English glass, came late into vogue, at a time when the prevailing fashions allowed little room for any freedom of treatment, so that it is only rarely that we can find any merit in the forms and decorations of individual examples.

It is, however, to a somewhat earlier period that the modern enthusiast turns. His interest lies in the air-twisted stems, the folded feet, and the bell-shaped bowls of the drinking-glasses of the eighteenth century. Now these, though made of flint glass, belong mostly to a time before full advantage had been taken of the dispersive power of that material upon the rays of light. Here the question may well be asked—putting aside all matter of historical or sentimental interest—what can we say of these endless rows of glasses, classified and sub-classified on the ground of variety of stem or bowl, as objects of art? But this is a point upon which I should prefer not to deliver a definite judgment; I have said enough to indicate my personal standpoint. I can only refer the reader to the copiously illustrated work of Mr. Hartshorne on English glass, of which the larger part is occupied with this branch of the subject.^[228]

It may be said that the history of English glass divides itself into two periods. For the first we have abundant documentary evidence—patents for new processes and petitions for or against these patents, to say nothing of notices in contemporary journals and memoirs—but against this an almost total absence of examples of the glass actually made. This period extends from the early days of Elizabeth almost to the end of the seventeenth century. In the second period, on the other hand—and this includes nearly the whole of the eighteenth century—the documentary evidence almost completely fails us; but in its place a fairly rich material harvest is available—the wine-glass, above all, so dear to the collector, now asserts itself.

When at the beginning of the reign of Elizabeth, or even a little earlier, a few rays of light begin to be thrown upon the glass made in England, we find the industry centred in a district on the borders of Surrey and Sussex: we are here at the western extremity of the great forest of the Weald, that was a little later to become for a time the home of an important iron industry. Here the raw materials and the fuel were at hand. Fuel from the oaks and beeches, and from trees of smaller growth; the silica from the ‘Hastings sands,’ selected from spots where the beds were tolerably free from iron; and finally the alkali, for the most part from the ashes of the bracken that then as now grew so abundantly in the glades of the woods. For this old English glass, like that of France, was essentially a verre À fougÈre,^[229] made in districts remote from towns. At a somewhat later time the glass-workers were indeed forbidden to set up their furnaces within twenty-two miles of London, seven miles of Guildford, or within four miles ‘of the foot of the hills called the Sussex downs.’

The little village of Chiddingfold, just within the boundary of Surrey, may perhaps lay claim to be the original ‘metropolis of English glass,’ and a line measured from Hindhead to Petworth passes close to the various places—Loxwood, Kirdford, Fernfold, Wisboro’ Green—where we know that furnaces were already established early in the sixteenth century. I have already referred to this district when speaking of the English glass of mediÆval times (see p. 139). Fragments of green glass have been found on the site of a glass-house at Chiddingfold. In the Museum at Lewes are two bulbous flasks with long necks of this green Weald-glass. There was another centre of the glass industry in East Sussex, in the country to the north of Hastings. In a mediÆval document concerning Beckley, in this district, the name Glassye Borough occurs. At these woodland glass-houses, for many generations, the wandering pedlars, the ‘glass-men,’ had been wont to renew the stock of ‘vrynells, bottles, bowles, cuppis to drinck and such lyke,’ that they hawked along the country-side. You may send, says Thomas Charnock in his Breviary of Philosophy (1557), to Chiddingfold, to the ‘glassemaker,’

That is to say, that the glass-blower, as we have seen in other cases, worked from the patterns provided by his customers.

Camden says of the Sussex glass that in his time it was only used ‘of the common sort.’ Possibly the Sussex glass-blowers made quarrels and bull’s-eyes for windows also;^[230] this, however, was an industry that centred rather in London, especially in Southwark. Now it was above all the demand for larger and better made panes for use in the new mansions with spacious windows—the ‘glass houses’ of the proverb about throwing stones—that were now springing up on every side, that gave the most powerful impulse to the introduction of the newer methods of working glass that had already taken root in France and in the Low Countries. It must be remembered that in the preparation of the stained glass for church windows large pieces were not required. Considerable artistic skill in this branch would be quite compatible with a very primitive method of blowing and ‘flashing’ the glass. At this time the new industry—the making of large sheets of broad-glass, that is to say—was centred in Lorraine, in the country stretching from the Vosges to the Ardennes; in a lesser degree in Normandy. It is uncertain in what the superiority of the ‘verre en tables quarrÉes’ made by the Lorrainers consisted; there is no positive proof that they had as yet adopted the German cylinder process (see pp. 129 and 234 note), though this is in every way probable.

The French glass-workers who came to England belonged, for the most part, to the old noble families. We find in our English documents some of the very names—Hennezel, for instance—that occur in the famous Charte des verriers granted by John of Calabria, son of King RenÉ, in the year 1448 (see p. 230).^[231] When these foreigners are mentioned in our English documents they are invariably described as gentlemen or esquires.

We must remember that in the sixteenth century Antwerp held a commercial position something like that taken later by Amsterdam and London: the town was, above all, the centre of the glass trade. It is not surprising then to find that it was through the medium of an Antwerp merchant, one Jean CarrÉ, that the French glass-makers were now introduced into England.^[232] CarrÉ, in association with a certain Briot, brought over both Normans and Lorrainers, and the quarrels and disputes that soon broke out appear to have had their origin in the fact that the men to whom the first patents were granted were not practical workers themselves, and that they were therefore dependent on others.^[233] In any case, before the year 1570, gentlemen of Lorraine bearing the well-known names of Hennezel, Du Thisac, and Le Houx, as well, probably, as representatives of the Le Vaillant and other Norman families, were making glass in more than one spot in the Weald as well as in London.

But these proud, hot-headed foreigners do not seem to have been popular in Sussex. There were frequent petitions against the destruction of the woods to supply the fuel for their glass-houses, and we hear of an attempt made to rob the ‘outlandish men’ that made glass near Petworth and to burn their houses. Before 1576, then, the Lorrainers were already in search of forests where they could work without hindrance; they began that long peregrination that took them by way of the Hampshire woods to the Forest of Dean, and finally to Stourbridge and Newcastle.^[234]

Some remains of a glass-house at Buckholt Wood, on the line of the old Roman road between Salisbury and Winchester, had long attracted the attention of antiquaries before a satisfactory explanation of their origin could be found. Large quantities of broken window-glass, as well as fragments of glass of many other kinds, including some of distinctly Venetian type, had at times been dug up. These remains, doubtless, represent a store of ‘cullet’ or old broken glass destined to be remelted, and therefore not necessarily all of it made on the spot. Fragments, too, of the glass-pots were found, of a greyish-white clay not of local origin. It is only quite recently that with these discoveries have been associated certain entries in the registries of the Walloon Church at Southampton (these were published a few years ago by the Huguenot Society). Among those admitted to the Lord’s Supper, in the years 1576 to 1579, we find the names of members of the Du Thisac, Hennezel, and Le Houx families, all Lorrainers, as well as that of Pierre Vaillant, a Norman. These communicants are described in the registry as ‘Ouvriers de verre a la verriere de boute haut’ (elsewhere spelt Bocquehaut), a fairly good French rendering of the word Buckholt. It is not every day that one comes across so neat and conclusive an instance of documentary research supplementing and completing the work of the ‘men of the spade.’

But here again, in spite of the attraction of the not far distant Walloon Church, the Lorrainers made but a short stay. In 1599 one ‘Abraham Tysack, son of a frenchman at the glasse-house,’ was baptized at Newent, in the Forest of Dean, where, at any rate, there can have been no deficiency of fuel. But the wanderers made apparently no long stay in the district, for we find that some at least of the number after a few years settled at Stourbridge, in Worcestershire. The famous clay of this district, still unsurpassed as a material for the glass-pots, was, it would seem, already worked along with the beds of coal which this clay underlies. Here, at King’s Swinford, in 1612, the name of Tyzack occurs in local records, and a little later, at Old Swinford, those of Henzey and Tittery. In this neighbourhood some members of these families at length settled down, maintaining close relations with certain of their relatives who pushed on as far as Newcastle-on-Tyne. At this last town, in 1617, a Henzey was fain to enter the service of Sir Robert Mansell, who was already bringing the principal glass-workers of England within the net of his monopoly.

I have dwelt on the wanderings of these Lorrainers, who were above all makers of window-glass, as to them rather than to the Venetians is due, I think, the definite establishment of a glass industry in England. For it must be borne in mind that the principal stimulus came from the demand for better and larger panes for the windows of the new renaissance houses,—somewhat later, perhaps, for the windows of ‘glass-coaches’ also.

Already early in the sixteenth century not a few examples of Venetian and, perhaps, even of Oriental glass, may have found their way into the houses of the wealthy. But we must regard as quite exceptional—the result, probably, of some passing whim of the king—the collection of 371 pieces of glass that were in 1542 in the possession of Henry VIII. These are described under the head of ‘Glasses and sundry other things of erthe’ in an inventory of certain valuable effects in the Palace at Westminster (ArchÆological Journal, vol. xviii., 1861). Among them there is mention of flagons, basins, ewers, standing-cups, cruses, layers, spice-plates, and even forks and spoons of glass. Many of these pieces are described as ‘jasper-colour’—these were probably of a kind of schmelz—and there is frequent reference in the list to ‘blue glass’ and ‘glass of many colours.’ A ‘layer’ with the initials ‘H and A engraven on the cover,’ as well as a cup with ‘Quene Annes sipher engraven on it,’ had doubtless belonged to Anne Boleyn. The following items are of some interest:—

‘One thicke glasse of christall with a case of lether lined with crymson vellat.’

‘Three aulter Candlestickes of glasse.’

‘Oone Holly-water stocke of glasse with a bayle.’

‘Twelve bottles of glasse with oone cover to them all wrought with diaper work white.’ By this last expression are we to understand some kind of vetro di trina?

Finally, ‘One rounde Loking Glass sett in a frame of wood, vj cornered, painted under glass with the armes of Ingland, Spayne, and Castile’ carries us back to the days when Catherine of Aragon was queen. Of this method of decorating the frames of mirrors with inlay of glass painted on the inner surface I have already spoken. I would again refer the reader to the mirror in the Arnolfini Van Eyck at the National Gallery.^[235]

The earliest notice that we have of Venetian glass-workers in England carries us back to the year 1550, and it takes a form that is characteristic of the times. This is a petition to the Council of Ten, that has been found among the Venetian state papers. It is signed by no less than eight Muranese glass-workers, imprisoned in the Tower of London: they declare that they are threatened with the gibbet if they fail to work out their contract. These poor men were indeed between the devil and the deep sea; for did they delay their return to their homes they were liable, by a newly issued edict, to a long term in the Venetian galleys. It was only by the personal intervention of the young king that some arrangement was finally made that allowed of these Muranese glass-workers returning unmolested after working off part of their contract. One of these men indeed elected to remain behind, but he before long made his way to the Low Countries, and this first influx of Venetian workmen seems to have led to little as far as English glass was concerned.

Cornelius de Lannoy, from whom Cecil hoped so much, was perhaps as much an alchemist and a universal schemer as a worker in glass. He was set to work at Somerset House in 1564, but with little result, it would seem. He attributed his failure to the clumsiness of the English workmen and to the want of a suitable clay for his glass-pots.

It is to Jacopo Verzelini, a man evidently of some energy and resource, that we must give the credit of first successfully making the Venetian cristallo in England. When in 1575 he obtained a patent ‘for the makinge of all manner of counterfayt Venyse drinkinge glasses’ (but not, it would appear, of glass for windows), he was already established in London. Stow, writing a little later, says: ‘The first making of Venise glasses in England began at the Crotchet Friars, about the beginning of the reign of Q. Elizabeth, by one Jacob Vessaline an Italian.’ The Friars Hall, he tells us, ‘was made a glasse-house, wherein was made glasse of divers sorts to drincken.’ It was in this same hall probably that the unhappy craftsmen of Edward VI.’s time had been set to work. Verzelini, like other glass-workers of the period, reached England, it appears, by way of Antwerp. At any rate he was married to a lady of that town, of good family, who bore him twelve children. This we know from the monumental brass to his memory that may still be seen in the little church of Down in Kent, where in the year 1606 he was buried.

We see, then, that before the death of Elizabeth the making of both hollow ware and window-glass by the new methods was firmly established in London and in the provinces. Great complaints had already arisen of ‘the making of glass by strangers and outlandish men,’ and we hear of ‘the timber and woods spoiled by the glass-houses.’^[236] The same difficulty arose as in France. It was argued that the foreigner should be required to take native apprentices. But there is evidence that as late as the first quarter of the seventeenth century, the making of the better kinds of glass, the ‘Christalline Morana Glass,’ was still in the hands of Italians. This we have seen was for long the case in France as well. But we in England were in a measure dependent upon the foreigner for our window-glass also, this time upon the Lorrainer.

Of glass made in England during Elizabeth’s reign I can point to a goblet now in the British Museum. It is dated 1586, and bears an inscription in capitals of somewhat Gothic character—IN : GOD : IS : AL : MI : TRUST. The glass is engraved with the diamond, and is decorated with stringings of white enamel.^[237] The plain cylindrical glass tankard in the Gold Room is remarkable only for the silver-gilt mounting and for the arms of Cecil on the cover.^[238]

We have seen that early in the seventeenth century the French gentilshommes de verre were firmly established at Stourbridge and at Newcastle. Now by this time the outcry against the destruction of our English forests, the source of the timber for the navy, was becoming general. It was directed against the iron-smelters in the first place, and then against the makers of glass, above all against foreigners. ‘It were the less evil,’ says a proclamation of 1615, ‘to reduce the times into the ancient manner of drinking in stone and of lattice windows than to suffer the loss of such a treasure.’ It was in the Stourbridge district that Bub Dudley^[239] and others were occupied at this very time with the problem of smelting iron by means of pit-coal. With them was probably associated Thomas Percivall, to whom more than to any one else is to be given the credit of the first successful employment of coal in the glass-furnace.

Others were working on the same lines. To Sir William Slingsby and his associates a licence was issued in 1610, but this was a very general document, vaguely worded. More precise was the patent granted the next year to Sir Edward Zouche, Thomas Percivall, and others. It was under this patent that the process was perfected, probably at the glass-house at Lambeth, under the charge of Percivall. Only a few years later, in 1616, English coal was brought into use at the glass-works of St. Sever, near Rouen, very likely through the mediation of one of the Norman glass-workers settled in England.

There were many difficulties to be overcome before this pit-coal could be used with success. Greater care had to be taken in the selection of the materials for the pots—perhaps without the Stourbridge clay success would not have been attained—and it was found to be necessary to ‘close the pots,’ that is to say, to use a covered crucible so as to protect the glass from the smoky, sulphurous gases given off by the coal. The credit of the invention of these closed pots, with the mouth at the side facing the opening of the furnace, is also to be given to Percivall.

I dwell on these practical details for a special reason. In the first place, the use of coal and the consequent change in the form of the crucibles mark the beginning of English glass as a distinct genre. Again, this change is closely connected with a further and still more important step—the use of lead as an essential constituent in a new kind of ‘metal,’ the famous English flint-glass of later days. It is these two novelties that form our contribution to the technique of glass-making. Not that I can find any proof that lead-glass was made in England at so early a date. But on the one hand the use of a covered pot rendered it more difficult, at that time at least, thoroughly to melt the contents, and therefore favoured the use of a more fusible mixture; on the other, in the case of a glass containing lead, it is above all essential to protect the ‘metal’ from the fire.

The history of the progress of glass-making in England from the early days of Elizabeth to the outbreak of the Civil War in the next century, is chiefly concerned with the licences and patents granted to a succession of English and foreign ‘adventurers.’^[240] No doubt there were many abuses in this system; but it is impossible to overlook the fact that the Cecils and the other advisers of the Queen were enabled by such means to encourage the foundation of many industries, and this chiefly by the help of foreigners. For at the beginning of Elizabeth’s reign we had fallen sadly behind in the matter of the industrial arts. Not only France and Italy, but Germany too and the Netherlands, had much to teach us.

Already, however, before the death of the Queen and still more in the next reign, there arose, as I have said, a great popular outcry against the monopolists, and this feeling of indignation found an echo in more than one of James’s parliaments. It is the more strange, therefore, to find that it was during this reign that the whole glass industry of the country fell for the first and last time into the hands of one man. But this was no other than Sir Robert Mansell, Admiral of the Fleet, a man of exceptional energy and a born fighter, one who had in early life had more than one brush with the Spaniards. King James, when approached on the subject of Mansell’s glass monopoly, marvelled that ‘Robin Mansell being a seaman, whereby he hath got so much honour, should fall from water to tamper with fire.’

The first we hear of Mansell in this connection is in the year 1615, when we find him associated with Sir Edward Zouche, Thelwell, Percivall, and others in a patent for making glass with sea-coal. But before this he had probably for some time been interested in certain London glass-works. And now before two years had elapsed he had bought out all his partners^[241] and commenced his reign as ‘glass-king.’ This monopoly, in spite of frequently renewed opposition, Mansell succeeded in maintaining up to the time of his death in the days of the Protectorate. He hunted down the local glass-houses where wood, now forbidden by law, was still employed. He granted licences to some of the Lorrainers working at Stourbridge and elsewhere, while—as at Newcastle, where he had glass-works under his direct management—he took others of these foreigners into his employ. In London, on the other hand, at the glass-furnaces of Winchester House, which he now took over, Sir Robert employed Italians.

We here come into contact with another and not less interesting man, James Howell, like his master Mansell, a Welshman.^[242] Howell was in 1618 ‘steward of the glasse-house’ in Southwark, but he was glad to change this position for that of traveller for Mansell in Spain and Italy; for, so he writes to his father, ‘I should in a short time have melted away to nothing among these hot Venetians.’ His duties were now to obtain workmen from Italy, and the raw materials, especially the ‘barillia,’ from Spain. In the following year he brought over one of the famous Miotti family from Middelburg, and not long afterwards we find him writing from Alicante an interesting account of the ‘Barillia, a strange kind of vegetable that grows nowhere upon the surface of the Earth, in that perfection as here.’ ‘The Venetians have it hence,’ he continues, and he proceeds to give a detailed account of the method of preparation (Book I. section I. xxv.). Howell’s letters from Venice are most interesting, and have provided many ‘elegant extracts’ for later writers. For instance, there is a passage in which he speaks of ‘lasses and glasses,’ and of the brittleness that beauty shares with the mirrors of Venice^[243]—the rest of the passage is, however, rather too outspoken for our present taste.

The contention between Mansell and the anti-monopolists was above all warm about the year 1623, on the occasion of the renewal of his patent for another fifteen years, and the ‘New Patent,’ the ‘Reasons against the same,’ Mansell’s ‘Defence’ and his ‘Motives and Reasons,’ and finally the ‘Answer’ to this last, followed in quick succession. All these documents and pamphlets are reproduced by Mr. Hartshorne; they form indeed an important source of information for the history of English glass. From them we learn that Mansell, after many failures elsewhere and the expenditure of many thousand pounds, first at Newcastle successfully made window-glass with the native coal; that the clay for the pots was at the commencement brought from Staffordshire, but that as the English clay proved unsatisfactory, he obtained a better material at infinite cost ‘from beyond Roan in France,’ and finally from ‘Spawe in Germany.’ At the time he was writing he indeed protests that he had already sunk £24,000 in his ventures.

The precise position of Mansell after the expiration in 1638 of the second term of his patent is somewhat obscure, but he seems to have steered well among the troubles of the time and to have maintained his monopoly. At the period in question, he tells us he was producing ‘Ordinary Drinking Glasses’ for wine and for beer at four shillings and half a crown a dozen respectively, as well as mortar-glasses^[244] at one-and-fourpence a dozen. He was at the same time making beer and wine glasses of crystal (these were from two to three times as dear as the last), beside looking-glasses and spectacle-glass plates in rivalry with the Venetians; finally, with English materials, window-glass and ‘green-glasses.’

There is nothing in all this, or indeed in any of these patents and petitions, to point to the existence of lead-glass at this time. The use of barilla, I may add, is incompatible with the preparation of a lead-glass; in such a glass it is essential that the alkali should be potash. On the whole, during the long period of the Mansell monopoly (from 1615 to, say, 1655) little progress appears to have been made in the manufacture of glass, but of course we must make allowance for the times of civil strife that filled the latter part of this period.

After the Restoration the issue of patents began again. Everything points at this time to a renewal of interest in Venetian glass. When, however, in 1663 the Duke of Buckingham obtained his licence, his claim was based upon the improvements he had made in the looking-glass plates and in the plates for the glass-coaches. As in France, sheets of large size and good material were now in demand for both purposes. It was somewhat later, it would seem, that he turned his attention to making hollow ware in the Venetian fashion. Although nitre, a salt of potash,^[245] played an important part in the glass made by the duke, there is no proof that any use was made of red lead or of litharge. Evelyn, who in 1673 visited the duke’s ‘Italian glass-house at Greenwich where glasse was blown of finer metal than that of Murano at Venice,’ says nothing about such substances being employed.

But in spite of this progress in the home industry, the importation of chests of glass from Venice was at its height in the reign of Charles II. This we see from the correspondence of a London glass merchant, one John Greene (1667-1672), with a Venetian firm, which has fortunately been preserved.^[246] Along with these letters were found the ‘office copies’ of the patterns which Greene sent out to Venice as a guide to the glass-blowers. Here we have mention of ‘clouded calsedonia glasses’ for beer, claret, and sack, ‘creuits with or without feet, brandj tumblers,’ and ‘glasse floure potts.’ Not the least interesting item is the ‘Rhenish wine glasse,’ which is illustrated by a typical roemer with prunts on the stem, almost our only evidence of the use of these goblets in England. Greene advises his Venetian correspondent that the looking-glasses and the coach-glasses are to be packed at the bottom of the cases to escape if possible the search of the custom-house officials. What especially strikes one in examining the patterns of the drinking-glasses, which form the bulk of the orders (Hartshorne, Plates 30-32), is the fact that the stem or shank, so important a part of the eighteenth-century glass, is not yet developed; the conical bowl is separated from the foot by a simple or fluted bulb, or sometimes by two such bulbs or knops.

But this Venetian trade had now seen its best days; there are some hints of a falling off in Greene’s last two letters (1671-1672). On the other hand, during all this period the enterprising glass firms of the Netherlands kept up a close intercourse with England. As early as 1662 a patent for making various kinds of glass was obtained by one John Colenet, whom Mr. Hartshorne has very plausibly claimed as a member of the great glass-making family of Ghent and Namur, the De Colnets, so often mentioned in the letters of M. Schuermans. A few years later the tables were turned, for now the De Colnet firm was fain to engage an Englishman to produce ‘verre À l’Angleterre.’ In 1680 the great rival firm of LiÉge, the De Bonhommes, according to a document quoted by M. Schuermans (Letter vii.), was already making ‘flint-glass À l’Anglaise.’

Now this statement brings me face to face with what is the great crux in the history of English glass—the question, namely, when and where lead-glass was first applied to the manufacture of hollow ware.

But first I must say a word of a little book published in 1662. This is the already-mentioned translation by Christopher Merret of the Arte Vetraria of Antonio Neri (see p. 7). Merret, who was a man well abreast of the science of his day and an early, if not an original, member of the newly founded Royal Society, has supplemented Neri’s series of recipes with certain ‘Observations’ of his own. Here may be found some curious information concerning the materials used in the manufacture of the cristallo, for it is with this glass that the author is chiefly concerned. Merret does not appear to have had much acquaintance with the glass made in England in his day. For the practical details of the furnace and for the processes of glass-blowing he takes us back to Agricola. Both Neri and his translator are indeed for the most part occupied with the nature and preparation of the materials, and with the various methods by which glass may be coloured.^[247] Neri, like all the old writers, knew of the merits of lead-glass in the preparation of pastes for the manufacture of artificial gems; in his sixty-first section he tells us: ‘Glass of lead, known to few in this art, as to colour is the finest and noblest glass at this day made in the furnace. For in this glass the colours imitate the Oriental gems, which cannot be done in crystal. But unless diligence be used all sorts of pots will be broken, and the metal will run into the furnace.’ Upon this passage Merret observes: ‘Glass of Lead! ’Tis a thing unpractised in our furnaces, and the reason is because of the exceeding brittleness thereof.’ Lead, he continues, is indeed the principal ingredient in the glaze of the potter, ‘and could this glass be made as tough as Crystalline, ’twould far surpass it in the glory and beauty of its colours.’ Thus we see, with Merret as with Neri, the great merit of lead-glass is the capacity possessed by it of bringing out the colours of metallic oxides. They still regard the material from the mediÆval point of view. The bad working qualities of this glass of which Merret complains may very probably have been due to the fact that, starting from the basis of their cristallo, the glass-workers continued to use the soda-holding barilla instead of employing a potash salt.

The Venetians in the preparation of their cristallo laid great stress on the hard white pebbles, the cogoli, from the bed of the Po or of the Ticino; these they regarded as an essential constituent of a good glass. We in England, during the reign of Charles II., succeeded in replacing these pebbles by our native flints; and this English flint-glass,^[248] properly so-called, early acquired a good reputation on the Continent. The ingenious Mr. John Houghton, writing in 1683 (Letters for the Improvement of Husbandry and Trade), after speaking of our dependence upon the Venetians some years since, goes on to say: ‘Now by the fashion of using glasses in coaches and other good means we easily enough serve our neighbours.’ In 1682 he tells us there were exported from England two thousand five hundred and seventy-two drinking-glasses, besides some looking-glasses and ‘window chests.’ This confirms what I have said of the date when English flint-glass became well known in the Low Countries. Now it is generally taken for granted that by this time the term flint-glass had come to mean lead-glass. Certainly soon after the beginning of the next century lead-glass was already recognised as essentially a substance of English origin; but, as I have said, there is unfortunately not a word of evidence, documentary or otherwise, to show when or where this glass was first made, nor is it possible, I think, to point to any example of this lead-glass to which an earlier date than the first or second decade of the eighteenth century can be attributed. Indeed everything points to the English flint-glass of the last quarter of the seventeenth century being a form of the Venetian cristallo.

In any case it is essential to bear in mind that both in chemical composition and in physical properties no two things could be more unlike than the cristallo on which the early flint-glass, properly so called, was founded, and the lead-glass which afterwards usurped the name.^[249] The one is a typical soda-lime, the other an equally definite potash-lead glass, and the materials had to be sought for from entirely different sources.

The above-mentioned Mr. John Houghton, who every week, in the commercial paper edited by him, published an article on some technical or scientific subject, in the spring of 1696 devoted a series of these ‘leaders’ to the subject of glass. After some general reflections on the substance, when we are told, among other things, that ‘Vitrification is the last mutation of bodies of which Nature is capable and from which there is no going back,’ in his issue of May 2 he takes up the main subject. ‘According to my information,’ he tells us, ‘we are of late greatly improved in the art of Glass-making. For I remember the time when the Duke of Buckingham first encouraged glass-plates, and Mr. Ravenscroft first made Flint-glass.^[250] Since then we have mended our Window-glass and outdo all abroad. And what e’er may be said against Stock-Jobbery, yet it has been the Means to raise great Summs of Money to improve this Art.’ Again, on May 16 we are given a carefully classified list of ninety glass-houses existing in England. Of these, twenty-four were in London, nine at Bristol, seventeen at Stourbridge, and eleven at Newcastle. These glass-houses he divides into those for looking-glass plates, for bottles and for ‘Flint, Green, and Ordinary.’ Now the rational inference from all this seems to me to be that Houghton, who was in a position to know, knew nothing about lead-glass. The flint-glass houses are classed together with the ‘green’ and ‘ordinary,’ and flint-glass for him was glass made from flints.

So, as we have seen, Haudicquer de Blancourt, writing in France a few years earlier, knew nothing of lead-glass other than that used for objects of verroterie. It is at least evident that if our own glass-makers had mastered the art before the end of the century, the secret was well kept.^[251]

But before proceeding further, it may be well to form some definite idea of the composition of lead-glass and of the physical properties that led to its replacing in great measure the soda-lime glass of Venetian type. In the first place, as I have said, it is essential that the alkali in this glass (in the manufacture of hollow ware, at least) should be potash, and it was, perhaps, the fact that the lead was at first used along with soda that so long delayed the production of a ‘metal’ suitable for the manufacture of blown-glass. Again, the potash in the case of lead-glass must be something quite different from the impure material employed for the old green glass; this crude alkali contained, among other bases, a large percentage of lime. Saltpetre appears to have been used in the first place, and then a more carefully lixiviated form of vegetable ashes known as pearl-ash. The amount of lead oxide may vary from 28 to 40 per cent., and the specific gravity of the resultant glass from 2·8 to 3·6.

The great merit of lead-glass lies in its absolute transparency and brilliancy, combined with a certain darkness in the shadows. This brilliancy and fire, it is well to point out, are only indirectly dependent upon the refractive power exercised by the glass upon the rays of light that pass through it; in this respect lead-glass differs little from rock crystal or from the Venetian cristallo. But one quality it has which distinguishes it from all other kinds of glass as well as from nearly all transparent natural stones, the diamond, of course, excepted. This is the power possessed by it of dispersing the rays of white light: the elements of which this light is composed in passing through lead-glass are bent aside in different degrees, so that the issuing ray is broken up into its component colours. This it is that gives fire, but this fire is only fully brought out by means of facetted or angular surfaces. On this point—the distinction between refraction and dispersion—a good deal of confusion exists. The following table, which I borrow from a little book on gems by Professor Church, may help to clear up this point:—

We here see that lead-glass or flint-glass has little greater refractive power on light than rock crystal or the ordinary plate and crown glass of commerce which belongs to the same family as the cristallo of the Venetians. In dispersive power, on the other hand, it stands apart from both these substances and rivals the diamond in scattering the component rays of white light.