porcelain which he has used for some time, and which having been examined by competent artists, at the request of the Society of Arts, has been reported on very favourably. Mr. Rose's glaze is composed of 27 parts of felspar, 18 of borax, 4 of Lynn sand, 3 of nitre, 3 of soda, and 3 of the China clay of Cornwall. This mixture is melted together and ground to a fine powder; 3 parts of calcined borax being added previously to the grinding.

Glazes for porcelain and the finer kinds of earthenware are generally made with white lead, ground flints, ground flint-glass, and common salt; Lynn sand combined with soda, as a flux, being frequently added to the ingredients just mentioned. Almost every manufacturer uses a peculiar glaze, the recipe for which is kept secret by him as much as possible, under the idea of its superiority compared with that employed by his competitors, so that it is not possible to state proportions with accuracy. The French porcelain makers have given the composition of hard glazes made by them, which are all said to be formed of flint, ground porcelain, and crystals of calcined gypsum, in the following different proportions:

It is necessary to vary the composition of the glaze, in order to suit the different materials that form the body of the ware, since that would be a very fine glaze for one mixture of earths, which would be wholly inappropriate to another, proving deficient in lustre and being liable to crack. Before adopting any glaze in conjunction with a particular kind of ware, it is most prudent to make trial of it upon a small scale, in order to prove the suitableness of the bodies to each other.

This branch of the potter's art is greatly indebted to the extraordinary perseverance of a singular man, Bernard de Palissy, a native of France, who was born in

Agen at the close of the fifteenth century. His parents occupying a humble station in life, he was entirely indebted to his own unquenchable energy and perseverance for the success which crowned his industry.

The original occupation of Palissy was that of a draughtsman, to which pursuit he added land surveying. Accident having thrown into his hands an enamelled cup, he was immediately seized with the desire of improving the art, and thenceforward relinquishing all other occupations, gave up his whole time, mind, and substance, during several years, to the prosecution of experiments on the composition of enamel. He has himself given a narrative of his labours, sacrifices, and sufferings, during the progress of his pursuit, which is intensely interesting.

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In this account, Palissy represents himself as alternately planning and building, demolishing and rebuilding his furnace, at every step buoyed up by hope, and as often met, but not subdued, by disappointment; the object of remonstrance and derision to his associates, subject to the expostulations of his wife, and witness to the silent but more eloquent reproaches of his children. In other respects Palissy proved himself an amiable as well as a highly gifted man; for, notwithstanding that his efforts were ultimately crowned by success, standard whereby the judgment of mankind is most easily and therefore most usually formed, -one might hesitate to applaud a degree of perseverance which, for so long a time, materially interfered with the welfare of his family. Amidst all this scene of deprivation and disappointment, Palissy bore outwardly a cheerful countenance, and, throughout the lengthened trial, confined within the dungeon of his own breast, those feelings of bitterness which he has so forcibly described as being his portion

The extremities to which he was at one time reduced were such, that to provide fuel for feeding the furnace, his furniture and afterwards even some of the woodwork of his dwelling were destroyed; and in order to

silence the clamour of his assistant workman for the payment of wages, he stripped himself of a portion of his apparel. At length, however, these efforts were rewarded by complete success; and fame, honours, and independence were thenceforward his attendants through a long career of useful occupation.

Palissy's after pursuits were of a more general character, embracing the sciences of agriculture, chemistry, and natural history, upon which subjects he both wrote and lectured with ability and success.

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Nor did the firmness of his character forsake him for a moment to the end of his life. Being a protestant, and having ventured, in some of his lectures, to promulgate facts which made against the dogmas of the priests, he was, when in his ninetieth year, dragged by the infuriate zeal of these fanatics to the Bastile, and died, with consistent firmness, within its walls. His heroic reply, while thus imprisoned, to Henry III. is above all praise. 'My good man," said the king, "if you cannot conform yourself on the matter of religion, I shall be compelled to leave you in the hands of my enemies."-" Sire," replied the intrepid old man, "" I was already willing to surrender my life, and could any regret have accompanied the action, it must assuredly have vanished upon hearing the great king of France say I am compelled.' This, sire, is a condition to which those who force you to act contrary to your own good disposition can never reduce me; because I am prepared for death, and because your whole people have not the power to compel a simple potter to bend his knee before images which he has made."

So great is the competition among potters in the present day, that means which are injurious to their real quality are frequently adopted for rendering their wares less costly. Some makers are hence tempted to the employment of materials that will enable them, at a moderate price, to furnish articles apparently good, but which will speedily prove defective when brought into use. The saving which the manufacturer is able to effect, through

the adoption of an inferior glaze, consists not so much in the actual cost of its component parts, as in the smaller quantity of fuel required for its vitrification, and in the shorter period of time demanded for its conversion.

The earthenwares offered, at low prices, by hawkers and pedlers, and at inferior shops, are mostly composed of clay that will not bear a proper degree of heat in the oven, and are covered by a glaze so tender as to craze after a few cleansings with hot water. If exposed to a high temperature, or if acids be applied, the glaze will be dissolved, and the vessels consequently rendered useless. The quantity of lead which enters into the composition of the better kinds of glazes is so small, that the deteriorating and pernicious effects which attend upon the use of raw glaze need not be apprehended from their employment.

The seggars used to enclose the wares when baked in the gloss oven, are similar to those employed in the first firing. Previous to their insertion, the pieces must have the glaze wiped from the parts which immediately rest upon the bottoms of the seggars, otherwise they would adhere and might be broken in their removal. The cases are piled up in the manner already described, and just that degree of heat must be employed which will give perfect fusion to the glaze and cause it to spread regularly over the surface. The temperature, of course, varies according to the quality of the articles and the composition of the glaze; but, for the reason already stated, it must never be carried beyond the degree to which the biscuit has been previously exposed. In practice, the temperature of the gloss oven is generally less by about ten degrees of Wedgwood, or 1300 degrees of Fahrenheit's scale, than the heat of the biscuit oven.

As alkaline substances are so powerfully instrumental in promoting the fusion of intractable bodies, it may be thought, that by increasing their proportion when combined with felspar, glazes might be formed that would

fuse at a heat sufficiently moderate for any description of earthenware, and that, consequently, the use of oxide of lead, which is so pernicious, might be altogether abandoned but another serious evil which would then be experienced prevents this substitution. The glaze,

if it contained beyond a certain portion of alkali, would not undergo the same degree of expansion by heat as the body whereon it is laid, and would, as a consequence, crack to such a degree as, when brought into use, would allow any greasy matter to penetrate through to the body of the ware; and this would speedily destroy its coherency.

The qualities which it is the object of the manufacturer to give to porcelain of the finest description, are density, whiteness, transparency, and fine texture of the glaze. These properties are estimated in the order wherein they are here enumerated, compactness of body being the point which it is considered most desirable to attain. The glaze, as seen in the finished porcelain, should not put on a lustrous appearance; but while beautifully smooth to the touch, should present to the eye rather the softness of velvet than the gloss of satin. This peculiar semblance will only be produced with glaze that melts with difficulty, and when the heat has been raised precisely to, and not beyond, the point that is necessary for its fusion.

Stoneware is a very perfect kind of pottery, and approaches nearer than any other description to the character of porcelain. Its body is exceedingly dense and compact, so much so, indeed, that although vessels formed of it are usually glazed, this covering is given to them more with the view of imparting an attractive appearance than of preserving them from the action of liquids. When properly made and baked, stoneware is sufficiently hard to strike fire from flint, and is as durable as porcelain.

This kind of earthenware is composed of clay and flint. The proportion in which these ingredients are used is said to vary in different manufactories, and it