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Salted Paper Print
The salt print was the dominant paper-based photographic process for producing positive prints (from negatives) from 1839 until approximately 1860. The salted paper technique was created in the mid-1830s by English scientist and inventor Henry Fox Talbot. He made what he called "sensitive paper" for "photogenic drawing" by wetting a sheet of writing paper with a weak solution of ordinary table salt (sodium chloride), blotting and drying it, then brushing one side with a strong solution of silver nitrate. This produced a tenacious coating of silver chloride in an especially light-sensitive chemical condition. The paper darkened where it was exposed to light. When the darkening was judged to be sufficient, the exposure was ended and the result was stabilized by applying a ''strong'' solution of salt, which altered the chemical balance and made the paper only slightly sensitive to additional exposure. In 1839, washing with a solution of sodium thiosulfate ("hypo") was found to b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edinburgh Ale By Hill & Adamson C1844
Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh had a population of in , making it the List of towns and cities in Scotland by population, second-most populous city in Scotland and the List of cities in the United Kingdom, seventh-most populous in the United Kingdom. The Functional urban area, wider metropolitan area had a population of 912,490 in the same year. Recognised as the capital of Scotland since at least the 15th century, Edinburgh is the seat of the Scottish Government, the Scottish Parliament, the Courts of Scotland, highest courts in Scotland, and the Palace of Holyroodhouse, the official residence of the Monarchy of the United Kingdom, British monarch in Scotland. It is also the annual venue of the General Assembly of the Church of Scotland. The city has long been a cent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Thiosulfate
Sodium thiosulfate (sodium thiosulphate) is an inorganic compound with the formula . Typically it is available as the white or colorless pentahydrate (x = 5), which is a white solid that dissolves well in water. The compound is a reducing agent and a ligand, and these properties underpin its applications. Uses Sodium thiosulfate is used predominantly in dyeing. It converts some dyes to their soluble colorless "leuco" forms. It is also used to bleach "wool, cotton, silk, ...soaps, glues, clay, sand, bauxite, and... edible oils, edible fats, and gelatin." Medical uses Sodium thiosulfate is used in the treatment of cyanide poisoning. It is on the World Health Organization's List of Essential Medicines. Other uses include topical treatment of ringworm and tinea versicolor, and treating some side effects of hemodialysis and chemotherapy. In September 2022, the U.S. Food and Drug Administration (FDA) approved sodium thiosulfate under the trade name Pedmark to lessen the risk of oto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wayback Machine
The Wayback Machine is a digital archive of the World Wide Web founded by Internet Archive, an American nonprofit organization based in San Francisco, California. Launched for public access in 2001, the service allows users to go "back in time" to see how websites looked in the past. Founders Brewster Kahle and Bruce Gilliat developed the Wayback Machine to provide "universal access to all knowledge" by preserving archived copies of defunct web pages. The Wayback Machine's earliest archives go back at least to 1995, and by the end of 2009, more than 38.2 billion webpages had been saved. As of November 2024, the Wayback Machine has archived more than 916 billion web pages and well over 100 petabytes of data. History The Internet Archive has been archiving cached web pages since at least 1995. One of the earliest known pages was archived on May 8, 1995. Internet Archive founders Brewster Kahle and Bruce Gilliat launched the Wayback Machine in San Francisco, California ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silhouette
A silhouette (, ) is the image of a person, animal, object or scene represented as a solid shape of a single colour, usually black, with its edges matching the outline of the subject. The interior of a silhouette is featureless, and the silhouette is usually presented on a light background, usually white, or none at all. The silhouette differs from an line art, outline, which depicts the edge of an object in a linear form, while a silhouette appears as a solid shape. Silhouette images may be created in any visual artistic medium, but were first used to describe pieces of cut paper, which were then stuck to a backing in a contrasting colour, and often framed. Cutting portraits, generally in profile, from black card became popular in the mid-18th century, though the term ''silhouette'' was seldom used until the early decades of the 19th century, and the tradition has continued under this name into the 21st century. They represented a cheap but effective alternative to the portrait m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camera Obscura
A camera obscura (; ) is the natural phenomenon in which the rays of light passing through a aperture, small hole into a dark space form an image where they strike a surface, resulting in an inverted (upside down) and reversed (left to right) projector, projection of the view outside. ''Camera obscura'' can also refer to analogous constructions such as a darkened room, box or tent in which an exterior image is projected inside or onto a translucent screen viewed from outside. ''Camera obscuras'' with a lens in the opening have been used since the second half of the 16th century and became popular as aids for drawing and painting. The technology was developed further into the photographic camera in the first half of the 19th century, when ''camera obscura'' boxes were used to exposure (photography), expose photosensitivity, light-sensitive materials to the projected image. The image (or the principle of its projection) of a lensless ''camera obscura'' is also referred to as a " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latent Image
A latent image is an invisible image produced by the exposure to light of a photosensitive material such as photographic film. When photographic film is developed, the area that was exposed darkens and forms a visible image. In the early days of photography, the nature of the invisible change in the silver halide crystals of the film's emulsion coating was unknown, so the image was said to be "latent" until the film was treated with photographic developer. In more physical terms, a latent image is a small cluster of metallic silver atoms formed in or on a silver halide crystal due to reduction of interstitial silver ions by photoelectrons (a photolytic silver cluster). If intense exposure continues, such photolytic silver clusters grow to visible sizes. This is called ''printing out'' the image. On the other hand, the formation of a visible image by the action of photographic developer is called ''developing out'' the image. The size of a silver cluster in the latent ima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver Iodide
Silver iodide is an inorganic compound with the formula Ag I. The compound is a bright yellow solid, but samples almost always contain impurities of metallic silver that give a grey colouration. The silver contamination arises because some samples of AgI can be highly photosensitive. This property is exploited in silver-based photography. Silver iodide is also used as an antiseptic and in cloud seeding. Structure The structure adopted by silver iodide is temperature dependent: * Below 420 K, the β phase of AgI, with the wurtzite structure, is most stable. This phase is encountered in nature as the mineral iodargyrite. * Above 420 K, the α phase becomes more stable. This motif is a body-centered cubic structure which has the silver centers distributed randomly between 6 octahedral, 12 tetrahedral and 24 trigonal sites. At this temperature, Ag+ ions can move rapidly through the solid, allowing fast ion conduction. The transition between the β and α forms repre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calotype
Calotype or talbotype is an early photographic process introduced in 1841 by William Henry Fox Talbot, using paper coated with silver iodide. Paper texture effects in calotype photography limit the ability of this early process to record low contrast details and textures. The term ''calotype'' comes from the Ancient Greek (), "beautiful", and (), "impression". The process Talbot made his first successful camera photographs in 1835 using paper sensitised with silver chloride, which darkened in proportion to its exposure to light. This early "photogenic drawing" process was a ''printing-out'' process, i.e., the paper had to be exposed in the camera until the image was fully visible. A very long exposure—typically an hour or more—was required to produce an acceptable negative. In late 1840, Talbot worked out a very different ''developing-out'' process (a concept pioneered by the daguerreotype process introduced in 1839), in which only an extremely faint or completely i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightfastness
Lightfastness is a property of a colourant such as dye or pigment that describes its resistance to fading when exposed to light. Dyes and pigments are used for example for dyeing of fabrics, plastics or other materials and manufacturing paints or printing inks. The bleaching of the color is caused by the impact of ultraviolet radiation in the chemical structure of the molecules giving the color of the subject. The part of a molecule responsible for its color is called the chromophore. Light encountering a painted surface can either alter or break the chemical bonds of the pigment, causing the colors to bleach or change in a process known as photodegradation. Materials that resist this effect are said to be lightfast. The electromagnetic spectrum of the sun contains wavelengths from gamma waves to radio waves. The high energy of ultraviolet radiation in particular accelerates the fading of the dye. The photon energy of UVA-radiation which is not absorbed by atmospheric ozone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver Chloride
Silver chloride is an inorganic chemical compound with the chemical formula Ag Cl. This white crystalline solid is well known for its low solubility in water and its sensitivity to light. Upon illumination or heating, silver chloride converts to silver (and chlorine), which is signaled by grey to black or purplish coloration in some samples. AgCl occurs naturally as the mineral chlorargyrite. It is produced by a metathesis reaction for use in photography and in pH meters as electrodes. Preparation Silver chloride is unusual in that, unlike most chloride salts, it has very low solubility. It is easily synthesized by metathesis: combining an aqueous solution of silver nitrate (which is soluble) with a soluble chloride salt, such as sodium chloride (which is used industrially as a method of producing AgCl), or cobalt(II) chloride. The silver chloride that forms will precipitate immediately. : : It can also be produced by the reaction of silver metal and aqua regia; howev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Expo Mucha à Lancey 4
An expo is a trade exposition. It may also refer to: Events and venues * World's fair, a large international public exposition * Singapore Expo, convention and exposition venue ** Expo Axis, one of the world's largest membrane roofs, constructed for the 2010 Shanghai Expo ** Expo MRT station, part of the Singapore MRT Changi Airport Extension, built to handle fluctuating passenger volumes due to events at the adjacent Singapore Expo * Expo Tel Aviv, convention and exhibition venue * Floriade Expo, an international exhibition and garden festival in the Netherlands Arts, entertainment, and media Music * ''Expo'' (album), a 2005 album by Robert Schneider/Marbles * ''Expo'' (Magnus Lindberg), a 2009 10-minute musical composition by Magnus Lindberg * ''Expo'' (Stockhausen), a 1970 composition for three players by Karlheinz Stockhausen Other arts, entertainment, and media * ''Expo'' (magazine), a Swedish anti-fascist magazine * Expo Channel, a home shopping channel in Australia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver Nitrate
Silver nitrate is an inorganic compound with chemical formula . It is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides. It was once called ''lunar caustic'' because silver was called ''luna'' by ancient alchemists who associated silver with the moon. In solid silver nitrate, the silver ions are three- coordinated in a trigonal planar arrangement. Synthesis and structure Albertus Magnus, in the 13th century, documented the ability of nitric acid to separate gold and silver by dissolving the silver. Indeed silver nitrate can be prepared by dissolving silver in nitric acid followed by evaporation of the solution. The stoichiometry of the reaction depends upon the concentration of nitric acid used. :3 Ag + 4 HNO3 (cold and diluted) → 3 AgNO3 + 2 H2O + NO :Ag + 2 HNO3 (hot and concentrated) → AgNO3 + H2O + NO2 The structure of silver nitrate has been examined by X-ray crystallography se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
