A Treatise on the Origin, Progressive Improvement, and Present State of the Manufacture of Porcelain and Glass

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Page 104 - Yet by some such fortuitous liquefaction was mankind taught to procure a body at once in a high degree solid and transparent, which might admit the light of the sun, and exclude the violence of the wind...
Page 104 - Who, when he saw the first sand or ashes, by a casual intenseness of heat, melted into a metalline form, rugged with excrescences, and clouded with impurities, would have imagined, that in this shapeless lump lay concealed so many conveniencies of life, as would in time constitute a great part of the happiness of the world...
Page 104 - ... of nature, and succour old age with subsidiary sight. Thus was the first artificer in glass employed, though without his own knowledge or expectation. He was facilitating and prolonging the enjoyment of light, enlarging the avenues of science, and conferring the highest and most lasting pleasures ; he was enabling the student to contemplate nature, and the beauty to behold herself.
Page 27 - Its excellent workmanship, its solidity, the advantage which it possesses of sustaining the action of fire, its fine glaze, impenetrable to acids, the beauty and convenience of its form, and the cheapness of its price, have given rise to a commerce so active and universal, that, in travelling from Paris to...
Page 103 - MANY circumstances contribute to render glass one of the most curious and interesting of manufactured substances. Although perfectly transparent itself, not one of the materials of which it is made partakes of that quality. Exceedingly brittle while cold, it becomes, by the application of heat, so remarkably flexible and tenacious as to be convertible into every form that fancy may dictate or convenience suggest. Its great ductility is shown in a very striking manner by the slender filaments —...
Page 67 - The qualities by which porcelain is distinguished from the inferior productions of the potter 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...
Page 63 - I mix with 27 parts of felspar, 18 of borax, 4 of Lynn sand, 3 of nitre, 3 of soda, and 3 of Cornwall China clay. This mixture is to be melted to a frit, and is then to be ground to a fine powder, 3 parts of calcined borax being added previously to the grinding.
Page 160 - The polishing substance used is colcothal, an oxide of iron which remains in the retorts after the distillation of acid from sulphate of iron : the two surfaces are polished in succession. For silvering glasses an amalgam of mercury and tin-foil is used, and this by means of considerable and long-continued pressure is made to adhere to one of the surfaces of the plate. The processes here described are those used...
Page 65 - ... wrote and lectured with ability and success. 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.
Page 215 - ... conclude that this picture is continued through the whole thickness of the specimen, and that if the glass were cut transversely, the same picture of the duck would be found repeated in the several slabs ; a. conclusion which was still further confirmed by the transparent places of some beautiful colours upon the eye and breast that were observed. The painting has on both sides a granular appearance, and seems to have been formed in the manner of mosaic works, of single pieces, but so accurately...

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