Chinaware is a name given to porcelain (pottery made from kaolin), so called from China being the first country to supply it to Europeans. It is thought that the Chinese produced porcelain from ancient times, but it wasn't until around 500 AD that they perfected the art. Chinaware first came to Europe in the beginning of the 16th century and won immediate popularity for its beauty and novelty.
The European consumers thought it impossible to match the whiteness of Chinaware, until John Frederick of Saxony, an alchemist, discovered a means of producing a porcelain equal in whiteness to the Chinaware. This led to the establishment by the Government of a factory at Meissen which started to produce porcelain rivalling the Chinaware in beauty and quality.
In France also about the middle of the 18th century the celebrated factory at Sevres was set up and soon acquired a great renown. In England a porcfaiain work was established at Chelsea some years prior to 1745; it was made at Stratford-le-Bow about the same time, at Derby as early as 1750, at Worcester in 1751. About 1755 kaolin or porcelain clay was discovered in Cornwall, and this contributed greatly to improve the quality of English porcelain, which began to be largely manufactured in Staffordshire under the auspices of Josiah Spode and Thomas Minton.
Chinaware, when broken, presents a granular surface with a compact, dense, firm, hard, vitreous and durable texture. It is semi-transparent, with a covering of white glaze, clear, smooth, unaffected by all acids except hydroflouric acid, and able to withstand sudden changes of temperature. Research Chinaware
Enamel is a vitreous glaze of various colours fused to the surface of gold, silver, copper, and other substances. The art of enamelling, which is of great antiquity, was practised by the Assyrians and by the Egyptians, from whom it may have passed into Greece, and thence into Rome and its provinces, including Great Britain, where various Roman antiquities with enamelled ornamentation have been discovered. The enamelled gold cup given by King John to the corporation of Lynn, in Norfolk, proves that the art was known among the Normans. The Byzantines of the 10th century produced excellent cloisonne enamels on a gold base, the cloisonne process consisting in tracing the design in fillets of gold upon the gold plate and filling up the small moulds thus formed with enamels the design appearing in coloured enamels separated by thin gold partitions or cloisons. In some cases, however, the enamels were filled into hollows beaten out in the gold plate, which formed part of the field.
In the 12th century the town of Limoges acquired the high reputation for inlaid enamels which it held until the 14th century, aud re-acquired in the 16th for its painted enamels. The costliness of the sculptured ground had led the Italians early in the 14th century to substitute the practice of incising the design on the face of the plate, and then covering it with a transparent enamel. The further step, which made the Limousin workshops famous, consisted in the method of superficial enamelling, in which opaque colours or colours laid on a white opaque ground were used. The Limoges school degenerated greatly in the 17th century, but its method with certain modifications in detail is still employed.
The basis of all kinds of enamel is a perfectly transparent and fusibleglass, which is rendered either semitransparent or opaque by the admixture of metallic oxides. White enamels are composed by melting the oxide of tin with glass, and adding a small quantity of manganese or phosphate of calcium to increase the brilliancy of the colour. The addition of the oxide of lead, or antimony, or oxide of silver, produces a yellow enamel. Reds are formed by copper, and by an intermixture of the oxides of gold and iron. Greens, violets, and blues are formed from the oxides of copper, cobalt, and iron.
In the middle of the 18th century enamelling was largely applied to the decoration of snuff-boxes, tea-canisters, candlesticks, and other small articles. Of later years it was extensively applied to the coating of iron vessels for domestic purposes, the protection of the insides of baths, cisterns, and boilers, and the like. Enamelling in colours upon iron was common, iron plates being thus treated by means of various mixtures, and words and designs of various kinds being permanently fixed upon them by stencilling, for advertising, signboards, etc.
James Tassie was a Scottish artist. He was born in 1735 at Pollokshaws, Glasgow and died in 1799. After studying modelling at Foulis' academy in combination with Henry Quin at Dublin he invented a vitreous paste for the reproduction of gems. In 1766 he settled in London producing artificial gems, portrait medallions and cameos. Research James Tassie
The eye is the organ of vision of animals, consisting in man of the globe of the eye, the muscles which move it, and of its appendages, which are the eyelids and eyebrows, and the lachrymal apparatus. The walls of the globe of the eye are formed principally of two fibrous membranes; one white and opaque - the sclerotic (from the Greek skleros meaning hard) - which envelops two-thirds of the globe posteriorly; and the other transparent, and resembling a horny plate, whence its name, cornea (from the Latin. corneus, meaning horny). The sclerotic is a tough fibrous coat, and is the part to which the phrase 'white of the eye' is applied. In the front of the globe the sclerotic is abruptly transformed into the transparent portion (the cornea), which is circular, and which forms a window through which one can see into the interior.
A mucousmembrane, the conjunctiva, so named because it unites the eye to the lid, spreads over the anterior portion of the globe, and then folds back on itself and lines the internal surface of the, eyelids. On the internal surface of the sclerotic is a vascular membrane called the choroid. This is essentially the blood-vessel coat of the eyeball. The front part of the choroid terminates about the place where the sclerotic passes into the cornea in a series of ridges, the ciliary processes. The circular space thus left in front by the termination of the choroid is occupied by the iris, a round curtain, the structure seen through the cornea, differently coloured in different individuals. In its centre is a round hole, the pupil, which appears as if it were a black spot. The iris forms a sort of transverse partition dividing the cavity of the eyeball into two chambers, a small anterior chamber filled with the aqueous humour, and a large posterior chamber filled with vitreous humour. The iris consists of a framework of connective tissue, and its posterior surface is lined by cells containing pigment which gives the colour to the eye. In its substance are bundles of involuntary muscular fibres, one set being arranged in a ring round the margin of the pupil, the other set radiating from the pupil like the spokes of a wheel. In a bright light the circular fibres contract and the pupil is made smaller; but in the dark these fibres relax and cause the pupil to dilate more or less widely, thus allowing only that quantity of luminous rays to enter the eye which is necessary to vision.
Just behind the pupil is the crystalline lens, resembling a small, very strongly magnifying glass, convex on each side, though more so behind. The greater or less convexity of the surfaces of the lens determines whether the vision is long or short. The internal surface of the choroid, or rather the pigmentary layer which covers it, is lined by the retina or nervous tunic upon which the objects are depicted that we see.
The ocular globe is put in motion in the orbit by six muscles, grouped two by two, which raise or lower the eye, turn it inward or outward, or on its antero-posterior axis. In these movements the centre of the globe is immovable, and the eye moves round its transverse and vertical diameters. These three orders of movements are independent of each other, and may be made singly or in combination, in such a manner as to direct the pupil towards all points of the circumference of the orbit.
Each eye is furnished with two eyelids, moved by muscles, which shield it from too much light and keep it from being injured. They are fringed with short fine hairs called eyelashes; and along the edge of the lids is a row of glands similar to the sebaceous glands of the skin. The eyebrows, ridges of thickened integument and muscle, situated on the upper circumference of the orbit and covered with short hairs, also regulate to some extent the admission of light by muscular contraction. In reptiles, some fishes (sharks, etc), in birds, and in some mammals a third eyelid or nictitating membrane is present, and can be drawn over the surface of the eye so as to clear it of foreign matters, and also to modify the light.
The lachrymal apparatus is composed of, firstly, the lachrymal gland, which lies in a depression of the orbitalarch; secondly, of the lachrymal canals, by which the tears are poured out upon the conjunctiva a little above the border of the upper lid; thirdly, the lachrymal ducts, which are destined to receive the tears after they have bathed the eye, and of which the orifices or lachrymal points are seen near the internal commissure of the lids; fourthly, the lachrymal sac, in which the lachrymal ducts terminate, and which empties the tears into the nasalcanal.
The tears, by running over the surface of the conjunctiva, render it supple and facilitate the movements of the globe and eyelids by lessening the friction. The influence of moral or physical causes increases their secretion, and when the lachrymal ducts do not suffice to carry them off they run over the lids.
The retina renders the eye sensible of light, and we may therefore consider it as the essential organ of vision. The function of the other portions is to converge the luminous rays to a focus on the surface of the retina, a condition necessary for distinct vision and the clear perception of objects. The visual impressions are transmitted from the retina to the brain by means of the optic nerve. The two optic nerves converge from the base of the orbit toward the centre of the base of the skull, where there is an interlacement of their fibres in such a manner that a portion of the right nerve goes to the left side of the brain, and a part of the left nerve to the right side; this is called the chiasma or commissure of the optic nerves. The principal advantage of having two eyes is in the estimation of distance and the perception of relief. In order to see a point as single by two eyes we must make its two images fall on corresponding points of the retinas; and this implies a greater or less convergence of the optic axes according as the object is nearer or more remote.
According to one estimate, four-fifths of everything we know reaches the brain through our eyes. The eyes transmit constant streams of images to the brain by electrical signals. The eyes receive information from light rays. The light rays are either absorbed or reflected. Objects that absorb all of the light rays appear black, whereas those that reflect all the light rays appear white. coloured objects absorb certain parts of the light spectrum and reflect others. When you look at something, the light rays reflected from the object enter the eye. The light is refracted by the cornea and passes through the watery aqueous humor and pupil to the lens. The iris controls the amount of light entering the eye. Then the lens focuses the light through the vitreous humor onto the retina, forming an image in reverse and upsidedown. Light- sensitive cells in the retina transmit the image to the brain by electrical signals. The brain perceives the image the right side up.
To accommodate the eye to different distances the lens is capable of altering itself with great precision and rapidity. When we look at a near object the anterior surface of the lens bulges forward, becoming more convex the nearer the object; the more distant the object the more the lens is flattened. When the transparency of the cornea, the crystalline lens, or any of the humours, is destroyed, either partially or entirely, then will partial or total blindness follow, since no image can be formed, upon, the retina; but although all the humours and the cornea be perfectly transparent, and retain their proper forms, which is likewise necessary to distinct vision, yet, from weakness or inactivity of the optic nerve, or injury of the central ganglia with which it is connected, weakness of sight or total blindness may ensue. Defective vision may also arise from the crystalline lens being so convex as to form an image before the rays reach the retina (a defect known as short sight or myopia), in which case distinct vision will be procured by interposing a concave lens between the eye and the object of such a curvature as shall cause the rays that pass through the crystalline lens to meet on the retina; or the lens may be too flat, as is the case in old age, a defect which is corrected by convex lenses.
In the lower forms of life the organs of sight appear as mere pigment spots. Ascending higher, simple lenses or refracting bodies occur. Insects, crustaceans, etc, have large masses of simple eyes or ocelli aggregated together to form compound eyes - the separate facets or lenses being optically distinct, and sometimes numbering many thousands. In the molluscs well-developed eyes approaching in structure those of the highest animals are found; and in all vertebrate animals the organ of vision corresponds generally to what has been described, though they vary much in structure and adaptation to the surroundings of the animal. Research Eye
The hyaloid canal, also known as the canal of Stilling, is a thin fluid filled canal with a membranous lining extending through the center of the vitreous body from the optic nerve to the lens. Research Hyaloid Canal
The vitreous humor is a large compartment containing viscous fluid, a clear jelly-like substance, lying between the lens and the retina and making up most of the volume of the eyeball. The fluid keeps the retina in position and maintains the spherical shape of the eyeball. Research Vitreous Humor
Albumen or albumin is a substance, or rather group of substances, so named from the Latin for the white of an egg (albus) , which is one of its most abundant known forms. It may be taken as the type of the protein compounds or the nitrogenous class of food stuffs. One variety enters largely into the composition of the animal fluids and solids, is coagulable by heat at and above 160 degrees, and is composed of carbon, hydrogen, nitrogen, and oxygen, with a little sulphur. It abounds in the serum of the blood, the vitreous and crystalline humours of the eye, the fluid of dropsy, the substance called coagulable lymph, in nutritive matters, the juice of flesh, etc. The blood contains about seven percent of albumen. Another variety called vegetable albumen exists in most vegetable juices and many seeds, and has nearly the same composition and properties as egg albumen. When albumen coagulates in any fluid it readily encloses any substances that may be suspended in the fluid. Hence it is used to clarify syrupy liquors. In cookery white of eggs is employed for clarifying, but in large operations like sugar-refining the serum of blood is used. From its being coagulable by various salts, and especially by corrosive sublimate, with which it forms an insoluble compound, white of egg is a convenient antidote in cases of poisoning by that substance. With lime it forms a cement to mend broken ware.
In botany the name albumen is given to the farinaceous matter which surrounds the embryo, the term in this case having no reference to chemical composition. It constitutes the meat of the cocoa-nut, the flour or meal of cereals, the roasted part of coffee, etc. Research Albumen
Glazing is the covering of earthenware (pottery) vessels with a vitreous coating in order to prevent their being penetrated by fluids. Research Glazing
Vitreous Enamel is an opaque or transparent glaze, generally coloured, which adheres to a suitable metallic surface when applied in a liquid state. Research Vitreous Enamel
Analcime is a mineral of the zeolite group noted for its vitreouslustre, and has the formulae NaAlSi2O6ù2H2O and a relative hardness of 6. It is found in the cavities of intrusive and volcanic igneous rocks; often as clear shiny crystals and is associated with calcite and other zeolites. Analcime was first identified on islands off Sicily and was confirmed as a distinct mineral in 1797 by the French mineralogist Rene-Just Hauy. Research Analcime
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Chinaware
