# General Information (D)

D Layer
The D Layer is the lowest region of ionised gas in the ionosphere. It exists only during the hours of daylight, at an altitude of about 70 km.

Da Bai Fen
Da Bai Fen (meaning "contesting 100 points") is a trick taking card game for four players in fixed partnerships, with considerable depth and scope for skill. It is popular over a wide area of China. There is also an expanded version Zhao Pengyou (Looking for Friends) for six to twelve players with variable partnerships.

Dacoity
In the Penal Code, dacoity is defined as organised banditry by 5 or more persons. The word derives from the Hindustani word for a robber, dakait.

Dada
The dada is an artistic and literary movement founded in 1915 in Zurich.

Dads Army
Dads Army was a very successful BBC comedy set in a south-coast town in England, about a group of British home guard volunteers during the Second World War led by an arrogant Captain and a camp sergeant.

Dagobas
see "Tope"

Daguerreotype
Daguerreotype was the earliest process of photographic reproduction, and was so called after its inventor Louis Daguerre. A copper plate, polished and silvered, was sensitised by exposure to iodine vapour, and so coated with a fine layer of silver iodide. It was then exposed in a camera, like modern photographic film, but with a longer exposure time. It was afterwards removed and treated with mercury vapour, the mercury attaching itself to those areas which had been most exposed to light and settling there in a density proportionate to the strength of the light.

Dahabiyeh
A dahabiyeh is a broad, shallow-draught vessel with a sharp prow and sails used for conveying passengers on the Nile.

Daily Express
The Daily Express is a tabloid newspaper which was founded in 1900 by Pearson. At the time it strongly supported Chamberlain's tariff reform policy, and today is known for its strongly nationalist right-wing ideas.

Daily Mail
The Daily Mail is a tabloid newspaper. It was founded in 1896 and was the first halfpenny London morning newspaper.

Daily Mirror
The Daily Mirror is a tabloid newspaper. It was founded in 1903 chiefly as a journal for women, and modified in 1904 as a general illustrated newspaper. Today it is known as a sensationalist tabloid supporting the Labour party.

Daily Telegraph
The Daily Telegraph is a broadsheet newspaper which was established in 1855 as a 2d paper by Colonel Sleigh. Several months later it was bought by Levy who reduced the price to 1d. It was a Liberal supporting paper until 1878, then from 1886 it was unionist and raised funds for needy causes. Today it is nicknamed the 'Torygraph' from its strong support of the Conservative party.

Dak
Dak was the east Indian postal service. Properly a dak was a relay of men carrying letters, despatches and the like.

Dakin's Solution
Dakin's Solution is a disinfectant solution containing sodium hydrochlorite, rendered neutral by the addition of boric acid as a buffer. The disinfectant action of the solution is very rapid, but it has the disadvantage of being unstable and does not keep for more than about a week.

Dalapon
Dalapon is a pesticide based on sodium salt. Also known as:
basfapon B, dalapon sodium, 2-dichloropropionic acid, alpha-alpha-dichloropropionic acid,
2-dichlorpropionsaeure natrium, Dowpon, 2-DPA, gramevin, radapon, sodium dalapon,
sodium 2,2-dichloropropionate and unipon.

Dalmatic
A dalmatic is a sleeveless embroidered vestment worn by deacons in the Roman Church and the High Church section of the Anglican Church during the celebration of High Mass and at processions.

Dam
A dam is a structure constructed to hold back water and provide controlled flow for irrigation, storage and generation of electricity.

Damask
Damask is a material of silk, linen, etc., with a raised of flat pattern woven into it, and shading alternately light and dark, according to the angle of view. The name derives from Damascus where in the 12th century silk fabrics of a similar pattern were made.

Damaskeening
Damaskeening is the process of ornamenting iron and steel with designs produced by inlaying or encrusting with another metal such as gold or silver, by etching and the like.

Dammar Gum
Dammar Gum is a naturally occurring gum obtained from coniferous trees that grow in the East Indies and Philippines. Dammar gum is soluble in turpentine and is employed in varnish and lacquers.

Dance
Dance is a rhythmic movement of the body usually performed to music.

Dane-geld
Dane-geld (Danegeld, Danegelt) was a tribute paid to the Danes to stop their ravages in England. It was first raised by Ethelred II in 991, and again in 1003; and was levied after the expulsion of the Danes to pay fleets for clearing the seas of them. The tax was suppressed by Edward the Confessor in 1051; revibed by William I in 1068; and formed part of the revenue of the crown, until it was abolished by Stephen in 1136. The tax was levied on every hide of land (as much as one plough could plough) at a rate first of 1 shilling and later as much as 7 shillings.

Danegeld
see "Dane-geld"

Danegelt
see "Dane-geld"

Dantoin 685
Dantoin 685 is a preservative used in shampoos and deodorants. It contains formaldehyde and N-acetal and is highly toxic. It is also listed as DMDM hydantoin.

Darby Steam-Digger
The Darby steam-digger was a light traction engine designed for ploughing fields. It was first exhibited at Carlisle in 1880, and could cultivate one acre an hour to a maximum depth of 14 inches.

Dark Ages
The Dark Ages were the five or six centuries following the fall of the west Roman Empire, after the civilisation of Rome, based on unity and inter-communication had been destroyed by repeated barbarian invasions.

Dark Room
A dark room is a specially darkened studio used for photographic work. As much of the material used in photography is sensitive to light, many operations must be conducted in darkness.

Darlington Pair
A Darlington Pair is an electronic circuit using two transistors with the collectors connected together and the emitter of the first directly coupled to the base of the second. This configuration gives very high gains equal to the gains of the two individual transistors multiplied together.

Data
Data is information, especially that stored in a computer.

DataEase
DataEase is a package for users who hate to program but want to create custom database applications. It is menu-driven yet offers many powerful features available in other systems only through programming. You can set up a system complete with custom menus and help messages. Menus can have different levels of password protection, which adds security to the system. The package allows you to create a multiple-choice list for a particular field, thereby avoiding the need to design a cryptic coding system. It features financial and scientific functions as well as transaction processing. The report writer is based on the SQL query language. This can be difficult for the novice, although prompts help to compensate for this deficiency. Reports can be designed with data-entry screens, which let you specify different criteria for a report each time it is run. A Quick Report facility will do most of the design work, allowing users to add more advanced features. A library of report templates can be stored for future use.

Datatalk
Datatalk is a menu driven communications package that has an underlying command language that allows the user to automate most operations, including file collection, transmission and printing. It can also provide access to a remote PC where any DOS applications can be executed, but with the display and keyboard entry occurring locally. In addition to dumb terminal operation, Datatalk can emulate DEC VT52 and VT100, as well as Viewdata terminals. Unlike other programs on the market, the entire Viewdata character set can be viewed with any colour graphics or Hercules graphics board: no replacement ROM chips are needed. Datatalk can be used with modems that operate at speeds of up to 9600 baud. This package supports auto-dial and auto-answer modems and is packaged preconfigured for a wide variety of them. When emulating a Viewdata terminal, it will, if requested, capture screens for later viewing. It will also convert the graphics characters into normal text so that they can be loaded into other PC software. Up to 128 telephone numbers can be stored in the Datatalk telephone directory. The software will configure the serial port, select the correct terminal emulation, load pre-defined function keys, dial the number and perform automatic log-in. An optional file encryption module, Datacode, is available for users with sensitive data. Datatalk emulates TTY, TVI 920, IBM 3101, ADDS A2, Lear Siegler ADM3A and ADM11, IBM 3101, Newbury 8089, Cifer, DEC VT52, Datatalk, Viewdata and VT100 terminals. It is best suited for accessing Viewdata services, like Prestel. Datatalk has some limitations, for example the VT100 emulation is not as sophisticated as some other products. In particular, it will not scroll horizontally to view all 132 columns on an 80 column screen. The text editor is restricted to 200 lines. When using this product to remotely configure another PC, it will only work with software that inputs and outputs using the BIOS services.

Daturine
Daturine is the poisonous alkaloid found in the thorn-apple.

Day
A day is the time taken for the earth to rotate once on its axis. Astronomically a day is reckoned to begin at noon; for civil purposes, at midnight.

Daylight Saving Time
Daylight Saving Time is a device for the better utilisation of daylight by a temporary abandonment of sun-time in summer. It was first suggested in 1907 by William Willett, and implemented in 1916 in order to procure economy in light and fuel as an Act which provided that all clocks be put forward one hour for a period of about 5.5 months during the summer in England. This emergency measure was perpetuated by an Act of 1925, and adopted by many other European countries.

dBase III Plus
Ashton-Tate's dBase III Plus became an industry standard. The product line, beginning with dBase II (formerly known as Vulcan), which was the first database manager for the personal computer, was built around a powerful, flexible programming language. Many thirdparty vendors have chosen to support the dBase standard and there are a variety of add-on and work-alike products available. dBase III Plus includes The Assistant, a menu-driven program with some relational capabilities that leads you through the maze of dBase procedures using pull-down menus and context-sensitive help. The commands in The Assistant appear on the screen. The Applications Generator is a menu-driven dBase module that brings you through the process of creating a custom program and shows how to design screens, menus, and reports. dBase III Plus includes a Data Catalog to keep track of related files. When you enter "?" you get a list of all files currently available. The menu-driven query facility lets you define and save a filter criteria.

dBase IV
Ashton-Tate's dBase IV was a greatly enhanced version of dBase III Plus and provided more facilities for the power user to develop turnkey applications without the need to write code. The Control Center was an extension of The Assistant in dBase III Plus and was much more powerful. The Control Center let users open and close files, create views and reports, and run programs that provide the novice end-user with easier access to dBase files. Reports, forms, and queries produced through the Control Center generate dBase source code which can be edited. The Query By Example panel of the Control Center displays a visual representation of the data file. By specifying criteria within a view, you can select records, display fields, or combine data from several database files. Without leaving dBase IV, you can run DOS operations such as CHKDSK or DIR through the DOS window. dBase IV can save 47 indexes to a single file. Index files are automatically created with every database file. Each time you open a database file, the associated index file is automatically opened. This is much easier than opening data and index files separately as required in dBase III Plus. The new Application Generator writes all code necessary for incorporating forms, reports, and files into a turnkey application. The dBase/SQL command programming language lets you create, modify, or query databases using SQL commands. You can issue SQL commands from the dot prompt and include SQL procedures within dBase programs. This allows access to dBase files by mainframe and minicomputer users who are familiar with SQL. When dBase IV executes SQL commands, it first translates the code from SQL to actual dBase source code. This translation prevents users from accessing external SQL code. Enhancements to the programming language let you create two dimensional arrays, multichild relationships, and data validation support. A transaction processing procedure creates a transaction log file of changes made to
e files. This helps avoid data loss due to power shortages, inadvertent reboots, and system failures. When used with Ashton-Tate's Chart-Master, the dBase/Chart-Master Bridge let users graph data files. The report and form generator are WYSIWYG, so it is easier to develop forms and reports. The screen painter displays memo fields through a window, and a pseudo compiler increases the speed of all commands issued at the dot prompt up to ten times faster than in dBase III Plus. Memo fields can be searched, copied to and from, and are available for program control. This lets you program dBase IV to perform automatic queries on memo fields. Built-in printer drivers support bold, italics, underlining, superscript, and subscript printing.

DBM
dBM is an identifier meaning ''decibels referred to one milliwatt,'' the common reference point for power levels in telecommunications circuits.

dbrief
dbrief by Solution Systems is a custom language editor used for writing dBase compatible code and provides an integrated environment in which to develop applications. dbrief is a custom version of brief. In order to run dbrief you must have a copy of brief. dbrief is flexible and can be modified to fit programming needs. The program can be used to edit memo fields or program files in dBase.

Ddt
Ddt is an insecticide discovered in 1939 by Paul Muller.

De Haeretico Comburendo
De Haeretico Comburendo was a statute of 1401 against the Lollards. By it, a heretic convicted before a spiritual tribunal and refusing to recant was to be burned.

Debusscope
The debusscope is an instrument somewhat similar to a kaleidoscope, useful for devising patterns for calico-printers. It was invented in France around 1860.

Decahydro-naphthalene
Decahydro-naphthalene is naphthalene which has been completely reduced by catalytic hydrogenation. It is a colourless liquid with a pleasant odour and the formulae C10H18 used as a solvent and cleaning-agent.

Decalin
Decalin was a commercial name for Decahydro-naphthalene.

Decatur Staleys
see "Chicago Bears"

Deceleration
Deceleration is the rate at which a moving body decreases in velocity.

December
December is the twelth month of the year. It was originally the Roman tenth month of the year, hence the name from the Latin decem meaning ten. The British commenced their year on the 25th of December until the reign of William I.

Decennalia
Decennalia were festivals instituted by Augustus in 17 BC, and celebrated by Roman emperors every ten years of their reign with sacrifices, games and largesses.

Decibel
The decibel is the unit of measurement of sound intensity.
In electronics, the decibel is a unit of measurement representing the logarithmic a ratio of two voltages, currents or power levels; used in telecommunications to express transmission loss or gain; defined as one-tenth of a Bel, hence the appropriate notation is dB, shown here.

Declaration of Independence
The Declaration of Independence was made in 1776 by the 13 English colonies in North America breaking away from all allegiance to the British Crown. The Declaration was mainly the work of Thomas Jefferson. Already in December 1775 the Congress had declared itself independent of the English parliament and by this declaration had repudiated allegiance to the Crown.

Declaration of Indulgence
The Declaration of Indulgence in 1687 was a proclamation by James II repealing all religious tests and penal laws against Roman Catholics and Dissenters. The Declaration was republished in 1688 and ordered to be read in the churches. Their refusal to do this led to the trial of the Seven Bishops, who were acquitted.

Declaration of Paris
The Declaration of Paris in 1856 adopted with the Treaty of Paris to establish four principles of international law: 1) Privateering to be abolished; 2) the neutral flag might cover enemy goods except contraband of war; 3) neutral goods, except contraband of war, not to be subject to capture under an enemy's flag; 4) blockades, to be binding, must be effective, i.e. maintained by a sufficient force.

Decoy
Strictly speaking, a decoy is either a tame or artificial duck, so placed as to lure wild ducks within gunshot range. The term is widely applied to any means by which a person or animal is lured into a trap.

Defamation
In law, defamation is a false statement tending to expose another person to hatred, contempt or ridicule, or to injure him in his trade or profession. Mere insult is not sufficient.

Defence of the Realm Acts
The Defence of the Realm Acts (DORA) were a series of Acts passed during and after the Great War in Britain conferring on the King in Council the power to take extra-ordinary measures for the defence of the realm. Perhaps the most unpopular Act was the limitation of the times during which intoxicants could be sold, commonly known as the licensing hours and not relaxed until the 1990s.

Dehydration
In chemistry, dehydration is the removal of water from a substance.

Deimos
Deimos is one of the two moons of mars.

Dekatron
A dekatron is a gas-filled cold-cathode electron tube, having a central anode and ten effective cathodes, used in electronic counting circuits.

Delage
Delage were a make of successful French Grand Prix cars made between 1911 and 1927.

Deliquescence
A substance is deliquescent when it has an affinity for water strong enough to absorb it from the atmosphere in large quantities. Typically deliquescent salts are calcium chloride and ammonium nitrate.

Deliquescent
see "Deliquescence"

Delsym
Delsym is a tradename for dextromethorphan hydrochloride

Delta
Delta is the 4th letter of the Greek alphabet. In geography, a delta is an alluvial triangular deposit formed at diverging mouths of a river, the original delta is the island formed at the mouths of the Nile and so named by the Greeks from its resemblance to their letter delta (a triangle).

Delta Metal
Delta Metal is a variety of brass containing 55 percent copper, 41 percent zinc and 4 percent various other metals. It was invented in the 19th century by Dick and the original delta metal contained a small portion of iron. Delta metal was used in Geneva for making watch cases in 1885.

Delta Rays
Delta rays are a stream of electrons moving at a relatively low velocity.

Demerol hydrochloride
see "Meperidine hydrochloride"

Denaturant
A denaturant is a substance added to intoxicating liquids such as alcohol, so that while they are rendered unfit to drink are still usable in industry. However, the theory behind their use fails to appreciate the desperation of some alcoholics, and the drinking of methylated spirits despite being made more dangerous by the addition of toxic denaturants, is still just as widespread, but with even more injury occurring to those who consume it.

Denaturation
In chemistry, denaturation is the process of altering the structure of a protein by physical or chemical means.

Density
Density is the mass of a substance in relation to its volume, and usually expressed as the weight in grams of 1 cubic centimetre. Since volume enters into this dimension, and volume varies with temperature, it is essential that the temperature at which the measurement was taken is revealed when stating the density of a substance.

Dentil
In architecture, a dentil is one of a series of small square projecting blocks in the moulding of a cornice. They were originally employed as a decorative representation of the beam-ends of a wooden roof, the term has been extended to apply to objects made of wood.

Denudation
Denudation is a geological term for the wearing away of the earth's surface by the various agents - rain, frost, rivers, glaciers and ocean waves, each agent exhibiting a different kind of erosion.

Deodand
In old English law, deodand was a term denoting anything which had caused the death of a person, accidentally or otherwise, and was thereupon forfeited to the crown to be put to some good use.

Deoxygenation
In chemistry, deoxygenation is the process of removing water from a compound.

Depilatory
A depilatory is a substance which has the power to remove hair other than by cutting it. The term is generally applied to cosmetic hair removers.

Deposition
In geology, deposition is a term applied to the laying-down of material by the various agents, such as wind, rivers, lakes, oceans and glaciers, each deposit exhibiting distinct characteristics.

Derating
Derating is a scheme to encourage agriculture and industry by relieving them of a portion or the whole rates normally payable. the principle was introduced by Winston Churchill in the Budget of 1928 and incorporated in the Local Government (Derating) Act of 1929. The Act relieved agricultural land of the whole, and productive industry of three-quarters, of rates previously levied, and substituted therefor a lump sum government grant, distributed among the local authorities. The effect of derating was obscured by the subsequent industrial depression.

Dermatitis
Dermatitis is a term applied to many kinds of inflammation of the skin.

Derrick
A derrick is a lofty, portable, crane-like structure used on land and water for lifting enormous loads. They were invented in 1857 by Bishop for raising sunken vessels.

Desiccator
A desiccator is an apparatus used mainly in the laboratory, by which substances can be thoroughly freed from water.

Desk
A desk is a flat or sloping table used for reading, writing or drawing, with or without legs. In the Middle Ages a plank was generally used.

DESQview
DESQview by Quarterdeck Office Systems is a character-based multitasking operating environment that lets you open multiple application windows simultaneously and toggle between applications without losing your place. The product takes full advantage of enhanced expanded memory to allow multitasking.

Deuchars IPA
Deuchars IPA is a light Scottish ale brewed by the Caledonian Brewing Company of Edinburgh.

Deuterium
In chemistry, deuterium is an isotope of hydrogen having twice the mass of ordinary hydrogen.

Deuterogamist
A deuterogamist is someone who marries for a second time.

Deutoxide
A deutoxide is a compound of two atoms of oxygen to one or more of a metal.

Devonian
The Devonian was the sixth geological period, 300,000,000 years ago. It marked the evolution of the insects and amphibians.

Devonshire Colic
Devonshire colic (Painter's colic) is a species of colic caused by the introduction of lead into the system. It derives its name from its frequency amongst the former lead miners of Devon.

Dew
Dew is a precipitation in the form of moisture that collects on the ground after the temperature of the ground has fallen below the dew point temperature of the air in contact with the ground.

Dew-rake
A dew-rake is a fine rake used on lawns.

Dewanny
A dewanny is a court in the East Indies for trying revenue and other civil disorders.

Dextrin
Dextrin is a sticky mixture of water-soluble products, an intermediate stage in the hydrolysis of starch into sugars. It was formerly marketed as an adhesive under the name of "British Gum".

Di(2-ethylhexyl) phthalate
Di(2-ethylhexyl) phthalate, also commonly called bis (2-ethylhexyl) phthalate, is a colourless, oily liquid with a slight odour. It was patented in 1933, and is primarily used as one of several plasticizers in polyvinyl chloride (PVC) resins for fabricating flexible vinyl products. These PVC resins have been used to manufacture teething rings, pacifiers, soft squeeze toys, balls, shower curtains, raincoats, adhesives, polymeric coatings, components of paper and paperboard, defoaming agents, enclosures for food containers, animal glue, surface lubricants, flexible devices for administering parenteral solutions, and other products that must stay flexible and uninjurious for their lifetime. It is also used to manufacture vinyl gloves used for medical examinations and surgery. As a non-plasticizer, di(2-ethylhexyl) phthalate is used as a replacement for polychlorinated biphenyls (PCBs) in dielectric fluids for electric capacitors. It is also used as a solvent in erasable ink, an acaricide for use in orchards, an inert ingredient in pesticides, a component of cosmetic products, and a vacuum pump oil; it is used to detect leaks in respirators and to test air filtration systems. Di(2-ethylhexyl) phthalate is insoluble in water, miscible with mineral oil and hexane, and soluble in most organic solvents. It is easily dissolved in body fluids such as saliva and plasma. Di(2-ethylhexyl) phthalate is a combustible liquid; it may burn, but does not readily ignite. It produces poisonous gas in a fire. When heated to decomposition, it emits acrid smoke. Di(2-ethylhexyl) phthalate is also known as bis(2-ethylhexyl) phthalate, bis(2-ethylhexyl)-1,2-benzenedicarboxylate, di(2-ethylhexyl)ortho-phthalate, di-sec-octyl phthalate, 2-ethylhexyl phthalate, NCI-c52733, disec-octyl phthalate, 1,2-benzenedicarboxylic acid, bis (2-ethylhexyl) ester, DOP, DEHP, and octoil.

Diadem
A diadem was a head-band worn by the Romans instead of a crown. They were made of silk or wool, set with precious stones and consecrated to the gods.

Dialect
A dialect is a characteristic manner of speech confined to a particular locality and differing, to a greater or lesser extent, from the standard speech of the country. The distinction between dialect and language is one of expediency rather than science.

Dialogue
Dialogue is a form of literature consisting of a conversation between two or more characters and so having considerable affinities with drama.

Dialysis
Dialysis is a method of chemical analysis, depending upon the different degrees of diffusibility of substances in liquids. It was discovered by Thomas Graham in 1861.

Diammonium Sulphate
see "Ammonium Sulphate"

Diastase
Diastase is a substance which occurs in saliva and in the secretions of the pancreas. It is an enzyme which has the power to break down starch with the formation of sugars.

Diathermy
Diathermy is a therapeutic treatment in which heat is produced in body tissues by passing high-frequency electric currents through them.

Diazepam
Diazepam is another name for valium.

Diazo Compounds
Diazo Compounds are a group of organic compounds characterised by the presence of the group -N2-. They are prepared by means of the diazo reaction, which consists in treating a primary aromatic amine with nitrous acid. Salts of this type are used in the production of dyestuffs.

Dichloroethane
1,2-Dichloroethane is a clear, thick man-made liquid that is not found naturally in the environment. It has a pleasant odour and sweet taste. It is used primarily to make vinyl chloride and a number of other solvents that remove grease, glue, and dirt, including trichloroethane, trichloroethylene, perchloroethylene, vinylidene chloride, and ethyleneamines. It is also found in commercial solvents used by industry to clean cloth, remove grease from metal, and break down oils, fats, waxes, resins, and rubber. In the household, 1,2-dichloroethane can be found in some cleaning agents and pesticides; in some adhesives, such as those used to glue wallpaper or carpeting; and in some paint, varnish, and finish removers. It is also added to leaded petrol to prevent engine knock. 1,2-Dichloroethane is used as an insect fumigant for stored grains and in mushroom houses, as a soil fumigant in peach and apple orchards, and as an extractant in certain food processes. 1,2-Dichloroethane is volatile at room temperature; it is flammable and burns with a smoky flame. Small amounts of 1,2-dichlorethane released in water or onto soil can vaporize into the air. It does not remain in the air for very long but can remain in water for possibly more than 40 days. 1,2-Dichloroethane is miscible with alcohol, chloroform, ether, and chlorinated solvents, and soluble in common organic solvents. It is sparingly soluble in water. When heated to decomposition, it produces toxic fumes of hydrochloric acid. Other names for 1,2-dichloroethane are 1,2-ethylene dichloride; aethylenchlorid; alpha, beta-dichloroethane; borer sol; di-chlor-mul-son; dichloro-1,2-ethane; dichloroethylene; Dutch liquid or oil; ethane dichloride; ethane 1,2-dichloride; ethyleen dichloride; ethylene chloride; ethylene dichloride; freon 150; glycol dichloride; and sym-dichlorothane.

Dichloropropane
1,2-Dichloropropane is a colourless liquid belonging to a class of chemicals referred to as volatile organic compounds (VOCs). It is a man-made chemical used only in research and industry. High-purity 1,2-dichloropropane is marketed as a solvent. 1,2-Dichloropropane is also used as an intermediate in the synthesis of carbon tetrachloride, lead scavenger in petrol, textile stain remover, oil and paraffin extractant, scouring compound, and metal degreasing agent, especially prior to electroplating. Prior to the early 1980s, it was used agriculturally as a pesticide for citrus fruits, pineapple, soy beans, cotton, tomatoes, and potatoes. 1,2-Dichloropropane had been sold for consumer use in paint strippers, paint varnish, and furniture finish removers, as a low-cost alternative to methylene chloride, but those uses were discontinued by 1983. By the end of 1983, its use as a solvent for film production was also being phased out. 1,2-Dichloropropane has a chloroform-like odour and evaporates rapidly at room temperature. Degradation in both the atmosphere and groundwater is slow. It is a flammable liquid and produces poisonous gases, including chlorine, in a fire. Containers of the chemical may explode in fire. Vapors form flammable mixtures with air and may travel to a source of ignition and flash back. It is slightly soluble in water. 1,2-dichloropropane is also known as propylene dichloride; propylene chloride; 2,3-dichloropropane; and 1,2-D.

Dichroic Mirror
A Dichroic mirror is a mirror consisting of a glass plate on which is deposited a very thin film of metal. It will transmit light of a particular colour, but reflects light of other colours.

Dichrooscope
The dichrooscope is an optical apparatus invented by professor Dove of Berlin in 1860 for representing the interferences, spectra in coloured lights, polarisation of light etc.

Dicker
A dicker was a British measurement of gloves equal to ten dozen pairs and of hides equal to ten hides.

Didjeridu
A didjeridu is a musical wind instrument developed by the Australian aborigines.

Die-casting
Die-casting is a method of casting metals by forcing them under pressure into moulds of a strong and permanent character capable of repeated use. Die-casting is said to have originated with the advent of printing, which necessitated the production of sharply cast types in large numbers.

Dielectric
Dielectric is the name given to an electric insulating material. The application of an electric field to a dielectric results only in a displacement of electric charge within the material, due to the molecules becoming polarized and orientating themselves in the direction of the electric field.

Diethanolamine
Diethanolamine (DEA) is a detergent.

Dietheroscope
The dietheroscope is an appartus for godesy and teaching optics. It was invented by Luvini of Tunis in 1876.

Diethyl phthalate
Diethyl phthalate is a manufactured, colourless, oily liquid with a slight aromatic odour and a bitter taste. It is commonly used to make plastics more flexible, in products such as toothbrushes, automobile parts, tools, toys, and food packaging. It is also used in insecticides, mosquito repellents, aspirin, and cosmetics, including bath preparations, eye shadows, hair sprays, wave sets, nail polish, nail polish remover, nail extenders, detergents, aftershave lotions, and skin care preparations. Diethyl phthalate is used to manufacture celluloid; as a solvent for cellulose acetate in varnishes; as a fixative for perfumes; as a wetting agent; as a camphor substitute; as a diluent in polysulphide dental impression materials; and as a solvent for nitrocellulose and cellulose acetate. It is used as a plasticizer in solid rocket propellants and cellulose ester plastics such as photographic films and sheets, blister packaging, and tape applications. Diethyl phthalate is soluble in alcohol, ether, acetone, benzene, vegetable oils, ketones, esters, aromatic hydrocarbons, and aliphatic solvents. It is compatible with polar polymers and additives over a wide range of compositions. When heated to decomposition, it emits acrid smoke. Diethyl phthalate is also known as 1,2-benzenedicarboxylic acid diethyl ester; ethyl phthalate; diethyl o-phthalate; o-benzenedicarboxylic acid diethyl ester; diethyl ester phthalic acid; phthalol; DEP; and diethyl-o-phenylenediacetate.

Diethyl-barbituric acid
see "Veronal"

Dieu et mon droit
Dieu et mon droit (God and my right) is the motto of the English royal family. It was first assumed as a motto by Henry VI.

Differenzler Jass
Differenzler Jass is a popular Swiss Jass game in which the players must predict in advance how many points they will take in tricks. You get penalty points according to the difference between the number of points you take in the play and your predicted total. If you get it exactly right you can deduct 10 points from your penalty point total (except that there is no bonus for predicting and making zero). There is no score for Stöck or Weis. Match (all the tricks) counts as 157 points taken.

Diffusion
In chemistry, diffusion is the process by which one substance distributes itself uniformly through water.

Diffusionism
Diffusionism is the theory that human culture was spread by degrees by outward expansion from a single source, as opposed to the view that cultures are developed independently and are only diffused when a particular people develops a more or less permanent type of culture which is well in advance of that of neighbouring peoples and becomes impressed upon the latter.

Digamma
Digamma was an ancient Greek letter, which was already obsolete in classical times, and so called because its form resembled a double gamma. It was pronounced like an English w.

Digested
see "digestion"

Digestion
Digestion is the process of absorbing and distributing substances from ingested food to the body.

Dihydroxyphenylalanine
Dihydroxyphenylalanine (dopa) is an intermediate in the natural synthesis of adrenaline and of the pigment melanin. In the nervous system, dihydroxyphenylalanine is converted first to dopamine and then to noradrenaline and then to adrenaline.

Dihydroxysuccinic acid
see "Tartaric Acid"

Dilatometer
A dilatometer is an apparatus used to measure changes in volume of solids. The solid is placed in a glass bulb with a capillary tube, and the bulb and part of the tube are filled with a liquid which is without action on the solid. By observing the liquid's position in the tube, changes in the volume of the solid may be measured.

Dilaudid
see "Hydromorphone hydrochloride"

Dimethicone
Dimethicone gives a smooth feel to a cosmetic cream or lotion. Various allergic reactions and internal problems make it questionable as a cosmetic ingredients. Although it's still widely used, many herbal oils, such as vegetable glycerin, can easily replace it.

Dimethoxy-strychnine
see "Brucine"

Dimethyl-xanthine
see "Theobromine"

Dimethylformaldehyde
see "Acetone"

Dimethylmethane diethylsulphone
see "Sulphonal"

Dimity
Dimity is a strong cotton material with raised patterns, usually white, used for curtains and especially bed-curtains during the 18th and 19th centuries.

Dimorphism
Dimorphism is a special case of polymorphism; the state when the same substance can appear in two different crystalline forms. Ice for example can exist as ordinary light ice, or if frozen below minus 20 degrees and subjected to high pressure forms dense ice which is heavier than water.

Dinghy
A dinghy is a small Indian river-boat. The term was adopted for the small row-boat attached to a larger vessel for general purposes and today is used to describe any small row-boat.

Dinitrotoluene
There are no natural sources of Dinitrotoluene (DNT), which is usually manufactured by mixing toluene with nitric acid in the presence of concentrated sulphuric acid. This reaction produces a mixture which consists of approximately 80% of the 2,4-isomer and 20% of the 2,6- isomer. Also produced are small quantities of other DNT isomers. Small concentrations of DNT isomers also occur as by-products in the production of trinitrotoluene (TNT). 2,4-DNT and 2,6-DNT are used primarily as intermediates in the production of flexible polyurethane foams used in the bedding and furniture industry. DNT is also used in the production of munitions and explosives, for which DNT is a gelatinizing and waterproofing agent. It is also used as an intermediate in the manufacture of dyes, and as a purified form, in smokeless gunpowders. 2,4-DNT is a highly reactive chemical and is a dangerous explosion hazard. It is combustible and may burn, but does not readily ignite. Poisonous gas is produced in a fire in which 2,4-DNT is burning. It is slightly soluble in water and soluble in alcohol ether, acetone, or benzene. 2,6-DNT is soluble in alcohol. 2,4-DNT is also known as benzene,1-methyl-2,4-dinitro-; and 2,4-dinitrotoluol. Synonyms for 2,6-DNT are benzene, 2-methyl-1,3- dinitro-; and 2,6-dinitrotoluol.

Diode
A diode is a thermionic valve with two electrodes, or a semi-conductor equivalent. It presents a high resistance one way around and a low resistance the other.

Diphenyl
Diphenyl is an alternative name for Phenyl benzene.

Dipole aerial
A dipole aerial is an aerial consisting of two straight conductors mounted in line, the connection being made to the two inner ends.

Dipsomania
Dipsomania is a form of alcoholism in which the subject exhibits periods of uncontrolled drinking alternating with periods of relative sobriety.

Diptych
A diptych was a two-leaved tablet of metal, ivory or other material used by the Greeks and Romans. In the early Christian church it was customary to inscribe the names of deceased bishops on diptychs. This practise was extended to include other distinguished persons who had deserved well of the church, and from it arose the calendars and martyrologies of a later period.

Directors
Directors is a strong English ale brewed by the Courage brewery.

Disaccharide
A disaccharide is a sugar of which the molecules are made up of two simple sugars, for example sucrose which is composed of glucose and fructose.

Disinfectant
A disinfectant is a substance applied to the outside of the body, or to non-living material in order to kill any micro-organisms which may be present.

Disk Piecharter
Disk Piecharter by Zorn Software is a Windows Filemanager extension that graphically shows disk usage per directory and per file. It allows you to zoom in and out on piechart segments, and enables you to delete whole directory trees (if desired) and shows the effect on free disk space.

Disorderly House
In law, a Disorderly House is a house where persons meet for unlawful purposes, such as a brothel or gaming-house.

Dispersion
In chemistry, dispersion refers to colloidal particles suspended in a liquid medium.

Displacement
Displacement is the size of a ship as measured by the actual weight of water which it displaces when afloat.

Dissection
Dissection is the process of cutting away and separating parts of a body, whereby its formation and the relationships of its parts can be observed.

Distaff
A distaff is a staff to which flax or any substance to be spun, is fastened.

Distillation
In chemistry, distillation is the evaporation of a liquid and the condensation of it's vapor.

Distributor
In a car, the distributor distributes electrical pulses to the spark plugs.

Dixie
The term Dixie refers to the southern states of the USA.

DNT
see "Dinitrotoluene"

Dobbm
Dobbm is an extremely popular card game in the Stubai valley among card players of all generations. It is unknown in the immediately surrounding regions, for example in the Wipptal and Innsbruck, but it is clearly related to Brixental Bauerntarock, Zuger Tapp and other similar games. Dobbm is also related to the special version of Tarock played in the same valley.

Doctor Wind
The Doctor Wind is a prevailing daytime breeze which blows onto the island of Jamaica from the sea.

Dog Days
The dog days are the hottest part of the year in Europe, being part of July and August. Formerly the dog days were specifically the period during which Sirius, the dog-star, rises approximately with the sun.

Domesday Book
The domesday book is a record of the survey conducted in England in 1086 by officials of William the conqueror in order to assess taxes etc.

Dominoes
Dominoes is a game played with 28 rectangular spotted tiles. It originated in Italy in the 18th century.

Donnapine
see "Phenobarbital"

Donnatal
see "Phenobarbital"

Doomsday book
see "domesday book"

Dopa
see "Dihydroxyphenylalanine"

Doppelkopf
Doppelkopf is an extremely popular card game in Germany, mainly in the North. It developed from a version of Schafkopf using a double pack of cards. Doppelkopf is a four player game with variable partnerships; the objective is to capture valuable cards in tricks. It can be played with five people, with dealer sitting out. Although the Deustcher Doppelkopf-Verband has developed standard rules for tournaments, in informal games there are many variants and each group of players has their own house rules.

Doppler effect
The Doppler effect is a change in observed wavelength due to relative motion between the source and observer.

DORA
see "Defence of the Realm Acts"

Doredin
see "Glutethimide"

Dosfolat
Dosfolat is a collection of vitamins used to improve reproduction in biological effluent treatment, and to reduce toxic shock.

Double Deck Pinochle
Double Deck Pinochle is a card game played with a deck of 80 cards, containing A 10 K Q J in each of the four suits, and with four identical copies of each card. This deck can be formed by mixing together two normal Pinochle decks, having thrown out the nines, or from four regular 52 card decks from which you throw out all the numerals 2 to 9. After the deal there is an auction in which players bid the number of points their team will try to win. Whoever bids highest has the privilege of choosing trumps and leading to the first trick. The object of the high bidder's team is to win at least as many points as the amount they bid. Points can be scored in two ways: by declaring and showing (melding) combinations of cards held in a players hand; by winning aces, tens and kings in tricks The game is won by the first partnership to achieve a score of 500 or more. If both sides reach 500 on the same hand, the bidding side wins.

Dover's Games
see "Cotswold Games"

DrafixCAD Ultra
DrafixCAD Ultra by Foresight Resources, proves that high-quality computer-aided design and drafting do not have to cost a lot. This product includes features that you would expect to find only in much more expensive packages. DrafixCAD Ultra lets you create and manipulate a range of items including lines, arcs, ellipses, and polygons. Each item can possess numerous attributes that can be selected or changed at any time. Lines and arcs can be trimmed, divided, or stretched. Intersections can be rounded or beveled. Symbols can be created, nested, and broken into their individual items. DrafixCAD Ultra allows you to copy, move, rotate, or scale an element, or mirror it about any axis. Elements may be designated by item, group, or region.

Draft-Spring
see "Draught-Spring"

Dragon's Blood
Dragon's Blood is a red resin obtained from the fruits of several East Indian trees. The material is a solid, soluble in alcohol and fatty oils, and used in the manufacture of furniture polishes, for staining marble and in some forms of printing.

Dram
The dram is a unit of the avoirdupois scale equivalent to 1.772 grams.

Dramaturg
In Theatre, a Dramaturg is a person who serves as an editor for a theatre company, helping to select plays and helping writers refine their work. He or she is sometimes called a literary manager.

Drams
see "dram"

Draught-Spring
A draught-spring (draft-spring) is a spring invented by Sir Alexander Gordon and intervening between the tug or trace of a draught animal and the load, whereby a jerking strain upon the animal is avoided. Later draught-springs were fitted between railway carriages to lessen the violence of the jerk communicated to them when the train started moving.

Draughts
Draughts is a game played by two people on a board of 64 alternate black and white squares. Each player has twelve pieces, one set are black and the other red.

Dray
A dray is an ancient form of low cart in which the shafts are elongated to form rails along which a load may be rolled onto the rear of the cart's inclined bed.

Dredger
A dredger is a ship used for picking up rubbish from waterways and removing materials from beneath the surface of the water.

Dress-coat
A dress-coat is a swallow-tailed coat or a coat with narrow pointed tails worn by gentlemen in evening dress.

Dress-guard
A dress-guard was a wing on the side of a carriage entrance to prevent the brushing of a lady's dress against the wheel as she got in or out of the carriage.

Dresser-copper
A dresser-copper is a vessel in which warps or threads are passed through boiling water.

Drift-piece
In shipbuilding a drift-piece was one of the upright or curved pieces of timber that connected the plank-sheer with the gunwale.

Drill
A drill is a machine for boring holes in rock, metal or wood etc. Drill bits were greatly improved from the invention in the 18th century of the twist drill, consisting of a rod of steel with a deep channel cut into it in a spiral, and the end ground off at an obtuse angle to give two cutting edges and a very short point.

Droggn
Droggn is a Tarock game for three players that comes from the Tyrol. Droggn is the local dialect form of the word Tarock. In recent times, as far as we know, it has only been played in the Stubai valley, south west of Innsbruck - mainly in Fulpmes and Telfes. It is unlike other Austrian Tarock games such as Königrufen, Zwanzigerrufen, Point Tarock and Strohmandeln. Those games developed in the eastern parts of Austria, but have never been well known in the Tyrol.

Drury Lane Theatre
The Drury Lane Theatre is an historic English theatre in London's West End. The first theatre on the site, the Theatre Royal, opened in 1663. As theatres often did in those days, it burned down nine years later, but was rebuilt again in 1874. From 1746 to 1776, Garrick was the resident star and co-manager. Richard Brinsley Sheridan succeeded Garrick as manager, and several of his plays were produced there. The theatre burned down again in 1809, was rebuilt in 1812. During the 1800s it was occasionally home to famous stars like Edmund Kean and George MacReady. In the latter 1800s it was associated with spectacular melodramas and stage machinery. Since the 1920s it has featured big, Broadway-style musicals.

Dry Ice
Dry Ice is a commercial name for solidified carbon dioxide, often used as a coolant. It is called dry ice because as it melts, it gives off a gas rather than a liquid, and so appears dry.

Dry Joint
In electrical terms, a dry joint is a soldered joint which, due to insufficient heating or lack of sufficient flux during the soldering operation, the solder has not adhered to the metals to be joined, thus producing a joint which is weak mechanically and of high electrical resistance.

Dry Rot
Dry Rot is a name given to the fungus Merulius lacrymans which attacks wood in houses. The name derives from the dry appearance of the wood after decay.

Dry-dock
A dry-dock is a dock from which the water may be emptied to allow of convenient and expeditious ship-repairs.

Dulcimer
The dulcimer was a musical instrument consisting of a resonance-board over which wires were stretched, these being struck by hammers held by the performer.

Duma
The Duma was the lower House of the Russian Imperial Parliament. It was created in 1905 by the Constitution granted by Tsar Nicholas II, and replaced in 1917 by the Soviet system.

Dungeon
A dungeon is an underground prison, originally in the keep of a Norman castle.

Durak
Durak is a popular card game in Russia. It would hardly be an exaggeration to say that every Russian who plays cards knows this game. "Durak" means fool, the fool in this game being the loser - the player who is left with cards after everyone else has run out. The game described on this page is properly called "Podkidnoy Durak", which means "fool with throwing in". This name refers to the fact that after an attack is begun, it can be continued by "throwing in" further cards whose ranks match those already played.

Duralumin
Duralumin is an alloy of aluminium, copper and magnesium, with traces of other metals. Typically duralumin is comprised of 94.4 percent aluminium, 4.5 percent copper, 0.95 percent magnesium and 0.76 percent manganese. If properly tempered it has an extremely high tensile strength and is used in aircraft construction.

Duren Piatkowy
Duren Piatkowy is a Polish card game for any number of players. An ordinary 52 card pack is used. If there are a lot of players, two or more identical packs can be shuffled together.

Duress
In law, duress is the unlawful constraint or compulsion of a person by physical action or threats.

Dutch East India Company
The Dutch East India Company was a chartered company formed in 1595 and granted a monopoly of trade in the Pacific and Indian Ocean in 1602. It was dissolved in 1798 and its territories taken over by the Dutch Government.

Dutch West India Company
The Dutch West India Company was a chartered company granted a monopoly of trade in the Atlantic Ocean with America and Africa by the Dutch Government in 1621.

DWIM
DWIM is an acronym for Do What I Mean. It is a term used in artificial intelligence for computer self-correcting of errors.

Dye
A dye is a substance applied to material, usually a textile, for decorative purposes, to give it a colour different from that which it originally possessed.

Dyke
A dyke (dike) is a ditch or earthworks. The term is most often applied to earthworks built to reclaim land from the sea or rivers.

Dynamics
Dynamics is the branch of mechanics which consists of the study of the motion of matter and its causes.

Dynamite
Dynamite is an explosive consisting of nitroglycerine which has been absorbed into some inert material such as kieselguhr, sawdust or wood pulp. Dynamite was invented by Nobel in 1867.

Dynamometer
A dynamometer is an apparatus for measuring power, or the rate of doing work.

Dyne
Dyne is the unit of force. One dyne is that force which, acting on a mass of one gramme, imparts to it an acceleration of one centimetre per second per second.

Dysprosium
Dysprosium is a rare metal element with the symbol Dy.

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