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Ramsay Grease
Ramsay grease is a vacuum grease, used as a lubrication and a sealant of ground glass joints and cocks on laboratory glassware, e.g. burettes. It is usable to about 10−2 mbar (about 1 Pa) and about 30 °C. Its vapor pressure at 20 °C is about 10−4 mbar (0.01 Pa). It is named after Sir William Ramsay. Different grades exist (e.g. thick or viscous, soft). The viscous one is used for standard stopcocks and ground joints. The soft grade is for large stopcocks and ground joints, desiccators, and for lower temperature use. Ramsay grease consists of paraffin wax, petroleum jelly, and crude natural rubber, in ratio 1:3:7 to 1:8:16. Due to the rubber content it has less tendency to flow. One recipe for a grease usable up to 25 °C consists of 6 parts of petroleum jelly, 1 part of paraffin wax, and 6 parts of Pará rubber. The dropping point of Leybold-brand Ramsay grease is 56 °C; its maximum service temperature is 25-30 °C. Its vapor pressure at 25 °C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Grease
Vacuum grease is a lubricant with low volatility and is used for applications in low pressure environments. Lubricants with higher volatility would evaporate, causing two problems: * They would not be present to provide lubrication. * They would make lowering the pressure below their vapor pressure difficult. As well as a lubricant, vacuum grease is also used as a sealant for joints in vacuum systems. This is usually limited to soft vacuums, as ultra high vacuum or high temperatures may give problems with the grease outgassing. Grease is most commonly used with glass vacuum systems. All metal systems usually use knife-edge seals in soft metals instead. Where O ring seals are used, these should ''not'' be greased (in static seals at least) as it can cause the O rings to become permanently distorted when compressed., p. 115 In electronics manufacturing processes, vacuum grease is often used to prevent corrosion. One of the early vacuum greases is the Ramsay grease. Examples ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petroleum Jelly
Petroleum jelly, petrolatum, white petrolatum, soft paraffin, or multi-hydrocarbon, CAS number 8009-03-8, is a semi-solid mixture of hydrocarbons (with carbon numbers mainly higher than 25), originally promoted as a topical ointment for its healing properties. The Vaseline brand is a well known American brand of petroleum jelly since 1870. After petroleum jelly became a medicine-chest staple, consumers began to use it for cosmetic purposes and for many ailments including toenail fungus, genital rashes (non- STD), nosebleeds, diaper rash, and common colds. Its folkloric medicinal value as a "cure-all" has since been limited by better scientific understanding of appropriate and inappropriate uses. It is recognized by the U.S. Food and Drug Administration (FDA) as an approved over-the-counter (OTC) skin protectant and remains widely used in cosmetic skin care, where it is often loosely referred to as mineral oil. History Marco Polo in 1273 described the oil exportation of B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Golf Ball
A golf ball is a special ball designed to be used in the game of golf. Under the rules of golf, a golf ball has a mass no more than , has a diameter not less than , and performs within specified velocity, distance, and symmetry limits. Like golf clubs, golf balls are subject to testing and approval by The R&A (formerly part of the Royal and Ancient Golf Club of St Andrews) and the United States Golf Association, and those that do not conform with regulations may not be used in competitions ''(Rule 5–1)''. History Early Balls It is commonly believed that hard wooden, round balls, made from hardwoods such as beech and box, were the first balls used for golf between the 14th through the 17th centuries. Though wooden balls were no doubt used for other similar contemporary stick and ball games, there is no definite evidence that they were actually used in golf in Scotland. It is equally, if not more likely, that leather balls filled with cows' hair were used, imported from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanolin
Lanolin (from Latin 'wool', and 'oil'), also called wool yolk, wool wax, or wool grease, is a wax secreted by the sebaceous glands of wool-bearing animals. Lanolin used by humans comes from domestic sheep breeds that are raised specifically for their wool. Historically, many pharmacopoeias have referred to lanolin as wool fat (''adeps lanae''); however, as lanolin lacks glycerides (glycerol esters), it is not a true fat. Lanolin primarily consists of sterol esters instead. Lanolin's waterproofing property aids sheep in shedding water from their coats. Certain breeds of sheep produce large amounts of lanolin. Lanolin's role in nature is to protect wool and skin from climate and the environment; it also plays a role in skin ( integumental) hygiene. Lanolin and its derivatives are used in the protection, treatment, and beautification of human skin. Composition A typical high-purity grade of lanolin is composed predominantly of long chain waxy esters (approximately 97% by weight) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dropping Point
The dropping point of a lubricating grease is an indication of the heat resistance of the grease and is the temperature at which it passes from a semi-solid to a liquid state under specific test conditions. It is dependent on the type of thickener used and the cohesiveness of the oil and thickener of a grease.Totten, G.E., ''Handbook of Lubrication and Tribology Volume 1: Application and Maintenance'', CRC Press, 2006, The dropping point indicates the upper temperature limit at which a grease retains its structure though is not necessarily the maximum temperature at which a grease can be used. Dropping point is used in combination with other testable properties to determine the suitability of greases for specific applications and for use in quality control. ASTM test procedure The dropping point test procedures are given in ASTM standards D-566 and D-2265. The test apparatus consists of a grease cup with a small hole in the bottom, test tube, two thermometers, a container, sti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hevea Brasiliensis
''Hevea brasiliensis'', the Pará rubber tree, ''sharinga'' tree, seringueira, or most commonly, rubber tree or rubber plant, is a flowering plant belonging to the spurge family Euphorbiaceae Euphorbiaceae, the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of a genus in the family. Most spurges, such as '' Euphorbia paralias'', are herbs, but some, ... originally native to the Amazon basin, but is now pantropical in distribution due to introductions. It is the most economically important member of the genus ''Hevea'' because the milky latex extracted from the tree is the primary source of natural rubber. Description ''H. brasiliensis'' is a tall deciduous tree growing to a height of up to in the wild, but cultivated trees are usually much smaller because drawing off the latex restricts the growth of the tree. The trunk is cylindrical and may have a swollen, bottle-shaped base. The bark is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Rubber
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and Indonesia are three of the leading rubber producers. Types of polyisoprene that are used as natural rubbers are classified as elastomers. Currently, rubber is harvested mainly in the form of the latex from the rubber tree (''Hevea brasiliensis'') or others. The latex is a sticky, milky and white colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called "tapping". The latex then is refined into the rubber that is ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for sale. Natural rubber is used extensively in many applications and products, either alone or in combination wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraffin Wax
Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and begins to melt above approximately , and its boiling point is above . Common applications for paraffin wax include lubrication, electrical insulation, and candles; dyed paraffin wax can be made into crayons. It is distinct from kerosene and other petroleum products that are sometimes called paraffin. Un-dyed, unscented paraffin candles are odorless and bluish-white. Paraffin wax was first created by Carl Reichenbach in Germany in 1830 and marked a major advancement in candlemaking technology, as it burned more cleanly and reliably than tallow candles and was cheaper to produce. In chemistry, ''paraffin'' is used synonymously with ''alkane'', indicating hydrocarbons with the general formula C''n''H2''n''+2. The name is derived from Latin ''parum'' (" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sealant
Sealant is a substance used to block the passage of fluids through openings in materials, a type of mechanical seal. In building construction ''sealant'' is sometimes synonymous with ''caulking'' and also serve the purposes of blocking dust, sound and heat transmission. Sealants may be weak or strong, flexible or rigid, permanent or temporary. Sealants are not adhesives but some have adhesive qualities and are called ''adhesive-sealants'' or ''structural sealants''. History Sealants were first used in prehistory in the broadest sense as mud, grass and reeds to seal dwellings from the weather such as the daub in wattle and daub and thatching. Natural sealants and adhesive-sealants included plant resins such as pine pitch and birch pitch, bitumen, wax, tar, natural gum, clay (mud) mortar, lime mortar, lead, blood and egg. In the 17th century glazing putty was first used to seal window glass made with linseed oil and chalk, later other drying oils were also used to make oil-bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desiccator
Desiccators are sealable enclosures containing desiccants used for preserving moisture-sensitive items such as cobalt chloride paper for another use. A common use for desiccators is to protect chemicals which are hygroscopic or which react with water from humidity. The contents of desiccators are exposed to atmospheric moisture whenever the desiccators are opened. It also requires some time to achieve a low humidity. Hence they are not appropriate for storing chemicals which react quickly or violently with atmospheric moisture such as the alkali metals; a glovebox or Schlenk-type apparatus may be more suitable for these purposes. Desiccators are sometimes used to remove traces of water from an almost-dry sample. Where a desiccator alone is unsatisfactory, the sample may be dried at elevated temperature using Abderhalden's drying pistol. Constituents The lower compartment of the desiccator contains lumps of silica gel, freshly calcined quicklime, Drierite or (not as effective) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Ramsay
Sir William Ramsay (; 2 October 1852 – 23 July 1916) was a Scottish chemist who discovered the noble gases and received the Nobel Prize in Chemistry in 1904 "in recognition of his services in the discovery of the inert gaseous elements in air" along with his collaborator, John William Strutt, 3rd Baron Rayleigh, who received the Nobel Prize in Physics that same year for their discovery of argon. After the two men identified argon, Ramsay investigated other atmospheric gases. His work in isolating argon, helium, neon, krypton, and xenon led to the development of a new section of the periodic table. Early years Ramsay was born at 2 Clifton StreetGlasgow Post Office Directory 1852 in Glasgow on 2 October 1852, the son of civil engineer and surveyor, William C. Ramsay, and his wife, Catherine Robertson. The family lived at 2 Clifton Street in the city centre, a three-storey and basement Georgian townhouse. The family moved to 1 Oakvale Place in the Hillhead district in his ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
