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Parchment
Parchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats. It has been used as a writing medium for over two millennia. Vellum is a finer quality parchment made from the skins of young animals such as lambs and young calves. It may be called animal membrane by libraries and museums that wish to avoid distinguishing between ''parchment'' and the more-restricted term ''vellum'' (see below). Parchment and vellum Today the term ''parchment'' is often used in non-technical contexts to refer to any animal skin, particularly goat, sheep or cow, that has been scraped or dried under tension. The term originally referred only to the skin of sheep and, occasionally, goats. The equivalent material made from calfskin, which was of finer quality, was known as '' vellum'' (from the Old French or , and ultimately from the Latin , meaning a calf); while the finest of all was ''uterine vellum'', taken from a calf foetus or sti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parchment From Goatskin
Parchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats. It has been used as a writing medium for over two millennia. Vellum is a finer quality parchment made from the skins of young animals such as lambs and young calves. It may be called animal membrane by libraries and museums that wish to avoid distinguishing between ''parchment'' and the more-restricted term ''vellum'' (see below). Parchment and vellum Today the term ''parchment'' is often used in non-technical contexts to refer to any animal skin, particularly goat, sheep or cow, that has been scraped or dried under tension. The term originally referred only to the skin of sheep and, occasionally, goats. The equivalent material made from calfskin, which was of finer quality, was known as ''vellum'' (from the Old French or , and ultimately from the Latin , meaning a calf); while the finest of all was ''uterine vellum'', taken from a calf foetus or sti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vellum
Vellum is prepared animal skin or membrane, typically used as writing material. Parchment is another term for this material, from which vellum is sometimes distinguished, when it is made from calfskin, as opposed to that made from other animals, or otherwise being of higher quality. Vellum is prepared for writing or printing on, to produce single pages, scrolls, codices, or books. Modern scholars and custodians increasingly use only the less specific, potentially-confusing term "membrane".Stokes and Almagno 2001, 114Clemens and Graham 2007, pp. 9–10. Depending on factors such as the method of preparation it may be very hard to determine the animal species involved (let alone its age) without using a laboratory, and the term avoids the need to distinguish between vellum and parchment. Vellum is generally smooth and durable, although there are great variations depending on preparation and the quality of the skin. The manufacture involves the cleaning, bleaching, stretching ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vellum
Vellum is prepared animal skin or membrane, typically used as writing material. Parchment is another term for this material, from which vellum is sometimes distinguished, when it is made from calfskin, as opposed to that made from other animals, or otherwise being of higher quality. Vellum is prepared for writing or printing on, to produce single pages, scrolls, codices, or books. Modern scholars and custodians increasingly use only the less specific, potentially-confusing term "membrane".Stokes and Almagno 2001, 114Clemens and Graham 2007, pp. 9–10. Depending on factors such as the method of preparation it may be very hard to determine the animal species involved (let alone its age) without using a laboratory, and the term avoids the need to distinguish between vellum and parchment. Vellum is generally smooth and durable, although there are great variations depending on preparation and the quality of the skin. The manufacture involves the cleaning, bleaching, stretching ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Writing Material
Writing material refers to the materials that provide the surfaces on which humans use writing instruments to inscribe writings. The same materials can also be used for symbolic or representational drawings. Building material on which writings or drawings are produced are not included. The gross characterization of writing materials is by the material constituting the writing surface (for example, paper) and the number, size, and usage and storage configuration of multiple surfaces (for example, paper sheets) into a single object (for example, a spiral notebook). Writing materials are often paired with specific types of writing instruments. Other important attributes of a writing material are its reusability, its permanence, and its resistance to fraudulent misuse. History Writing seems to have become more widespread with the invention of papyrus in Egypt. Parchment, using sheepskins left after the wool was removed for cloth, was sometimes cheaper than papyrus, which had to be impo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Papyrus
Papyrus ( ) is a material similar to thick paper that was used in ancient times as a writing surface. It was made from the pith of the papyrus plant, '' Cyperus papyrus'', a wetland sedge. ''Papyrus'' (plural: ''papyri'') can also refer to a document written on sheets of such material, joined side by side and rolled up into a scroll, an early form of a book. Papyrus is first known to have been used in Egypt (at least as far back as the First Dynasty), as the papyrus plant was once abundant across the Nile Delta. It was also used throughout the Mediterranean region. Apart from a writing material, ancient Egyptians employed papyrus in the construction of other artifacts, such as reed boats, mats, rope, sandals, and baskets. History Papyrus was first manufactured in Egypt as far back as the fourth millennium BCE.H. Idris Bell and T.C. Skeat, 1935"Papyrus and its uses"(British Museum pamphlet). The earliest archaeological evidence of papyrus was excavated in 2012 and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aqueous Solutions
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be represented as . The word ''aqueous'' (which comes from ''aqua'') means pertaining to, related to, similar to, or dissolved in, water. As water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry. Since water is frequently used as the solvent in experiments, the word solution refers to an aqueous solution, unless the solvent is specified. A ''non-aqueous solution'' is a solution in which the solvent is a liquid, but is not water. (See also Solvent and Inorganic nonaqueous solvent.) Characteristics Substances that are ''hydrophobic'' ('water-fearing') do not dissolve well in water, whereas those that are ''hydrophilic'' ('water-friendly') do. An example of a hydrophilic substance is sodium chlor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Librarian
A librarian is a person who works professionally in a library providing access to information, and sometimes social or technical programming, or instruction on information literacy to users. The role of the librarian has changed much over time, with the past century in particular bringing many new media and technologies into play. From the earliest libraries in the ancient world to the modern information hub, there have been keepers and disseminators of the information held in data stores. Roles and responsibilities vary widely depending on the type of library, the specialty of the librarian, and the functions needed to maintain collections and make them available to its users. Education for librarianship has changed over time to reflect changing roles. History The ancient world The Sumerians were the first to train clerks to keep records of accounts. ''"Masters of the books"'' or "keepers of the tablets" were scribes or priests who were trained to handle the vast amount and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archivist
An archivist is an information professional who assesses, collects, organizes, preserves, maintains control over, and provides access to records and archives determined to have long-term value. The records maintained by an archivist can consist of a variety of forms, including letters, diaries, logs, other personal documents, government documents, sound and/or picture recordings, digital files, or other physical objects. Description As Richard Pearce-Moses wrote: Determining what records have enduring value can be challenging. Archivists must also select records valuable enough to justify the costs of storage and preservation, plus the labor-intensive expenses of arrangement, description, and reference service. The theory and scholarly work underpinning archives practices is called archival science. The most common related occupations are librarians, museum curators, and records managers. The occupation of archivist is distinct from that of librarian. The two occupations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Graham (chemist)
Thomas Graham (21 December 1805 – 16 September 1869) was a British chemist known for his pioneering work in dialysis and the diffusion of gases. He is regarded as one of the founders of colloid chemistry. Life Graham was born in Glasgow, and educated at the High School of Glasgow. Graham's father was a successful textile manufacturer, and wanted his son to enter into the Church of Scotland. Instead, defying his father's wishes, Graham became a student at the University of Glasgow in 1819. There he developed a strong interest in chemistry, studying under Professor Thomas Thomson, who was impressed and influenced by the young man. He left the University after receiving his MA in 1824. He later studied medicine at the University of Edinburgh and then briefly taught chemistry at the Glasgow University Portland Street Medical School. In 1828 he was elected an Honorary Fellow of the Royal Society of Edinburgh, his proposer was Edward Turner. He won the Society's Keith Medal for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intestines
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus, stomach, and intestines. Food taken in through the mouth is digested to extract nutrients and absorb energy, and the waste expelled at the anus as feces. ''Gastrointestinal'' is an adjective meaning of or pertaining to the stomach and intestines. Most animals have a "through-gut" or complete digestive tract. Exceptions are more primitive ones: sponges have small pores ( ostia) throughout their body for digestion and a larger dorsal pore ( osculum) for excretion, comb jellies have both a ventral mouth and dorsal anal pores, while cnidarians and acoels have a single pore for both digestion and excretion. The human gastrointestinal tract consists of the esophagus, stomach, and intestines, and is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dialysis (chemistry)
In chemistry, dialysis is the process of separating molecules in solution by the difference in their rates of diffusion through a semipermeable membrane, such as dialysis tubing. Dialysis is a common laboratory technique that operates on the same principle as medical dialysis. In the context of life science research, the most common application of dialysis is for the removal of unwanted small molecules such as salts, reducing agents, or dyes from larger macromolecules such as proteins, DNA, or polysaccharides. Dialysis is also commonly used for buffer exchange and drug binding studies. The concept of dialysis was introduced in 1861 by the Scottish chemist Thomas Graham. He used this technique to separate sucrose (small molecule) and gum Arabic solutes (large molecule) in aqueous solution. He called the diffusible solutes crystalloids and those that would not pass the membrane colloids. From this concept dialysis can be defined as a spontaneous separation process of suspen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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