Research Results For 'Drain'

ASSAYING

Assaying is the estimation of the amount of pure metal, and especially of the precious metals, in an ore or alloy. In the case of silver the assay is either by the dry or by the wet process. The dry process is called eupellation from the use of a small and very porous cup, called a cupel, which is usually made of well-burned and finely-ground bone-ash or of magnesia. The cupel, being thoroughly dried, is placed in a fire-clay oven about the size of a drain-tile, with a flat sole and arched roof, and with slits at the sides to admit air. This oven, called a muffle, is set in a furnace, and when it is at a red heat the assay, consisting of a small weighed portion of the alloy wrapped in sheet-lead, is laid upon the cupel. The heat causes the lead to volatilize or combine with the other metals, and to sink with them into the cupel, leaving a bright globule of pure metallic silver, which gives the amount of silver in the alloy operated on. In the wet process the alloy is dissolved in nitric acid, and to the solution are added measured quantities of a solution of common salt of known strength, which precipitates chloride of silver. The operation is concluded when no further precipitate is obtained on the addition of the salt solution, and the quantity of silver is calculated from the amount of salt solution used.

An alloy of gold is first cupelled with lead as above, with the addition of three parts of silver for every one of gold. After the cupellation is finished the alloy of gold and silver is beaten and rolled out into a thin plate, which is curled up by the fingers into a little spiral or cornet. This is put into a flask with nitric acid, which dissolves away the silver and leaves the cornet dark and brittle. After washing with water the cornet is boiled with stronger nitric acid to remove the last traces of silver, well washed, and then allowed to drop into a small crucible, in which it is heated, and then it is weighed. The assay of gold, therefore, consists of two parts: cupellation, by which inferior metals (except silver) are removed; and quartation, by which the added silver and any silver originally present are got rid of. The quantity of silver added has to be regulated to about three times that of the gold. If it be more the cornet breaks up, if it be less the gold protects small quantities of the silver from the action of the acid. Where, as in some gold manufactured articles, these methods of assay cannot be applied, a streak is drawn With the article upon a touchstone consisting of coarse-grained Lydian quartz saturated with bituminous matter, or of black basalt. The practised assayer will detect approximately the richness of the gold from the colour of the streak, which may be further subjected to an acid test. The Goldsmith's Company of London is the statutory assay-master of all England.
Research Assaying

DRAIN-TRAP

A drain-trap, a contrivance to prevent the escape of foul air from drains, but to allow the passage of water into them. The most common form is a bent pipe resembling a letter U, whence the name U-bend, found in the plumbing of sinks and toilets.
Research Drain-Trap

DRAINING

In agriculture, draining is a method of improving the soil by withdrawing the water from it by means of channels that are generally covered over. The successful practice of draining in a great measure depends on a proper knowledge of the superficial strata, of their situation, relative degrees of porosity, etc. Some strata allow water to pass through them, while others more impervious force it to run or filtrate along their surfaces until it reaches more level ground below. In general where the grounds are in a great measure flat and the soils of materials which retain the excess of moisture, they require artificial means of drainage to render them capable of yielding good crops whether of' grain or grass.

The wetness of land which makes it inferior for agricultural purposes, may appear not only as surface-water but as water which flows through the lower strata, and to draw off these there are the two distinct operations of surface-draining' and under-draining. The rudest form of open drains are the deep furrows lying between high-backed ridges, and meant to carry off the surplus water after the soil is completely saturated, but in doing so they generally carry off also much of the best of the soil and of the manure which has been spread upon it. The ordinary ditch is a common form of water-course useful in certain cases, as in hill pastures. But covered drains at a depth of one metre or so are the common forms in draining agricultural lands. They are generally either stone-drains or tile-drains. Stone-drains are either formed on the plan of open culverts of various forms, or of small stones in sufficient quantity to permit a free and speedy filtration of the water through them. The box-drain, for instance, is formed of flat stones neatly arranged in the bottom of the trench, the whole forming an open tube.

In tile-drains, tiles or pipes of burnt clay are used for forming the conduits. They possess all the qualities which are required in the formation of drains, affording a free ingress to water, while they effectually exclude vermin, earth, and other injurious substances.

Drainage tiles and pipes have been made in a great variety of forms, the earliest of which, since the introduction of thorough draining, was the horse-shoe tile, so called from its shape. These should always rest on soles, or flats of burned clay. Pipe tiles, which combine the sole and cover in one piece, have been made of various shapes, but the best form appears to be the cylinder.

An important department of draining is the draining off of the waters which are the sources of springs. Sometimes the judicious application of a few simple drains, made to communicate with the watery layers, will often dry swamps of great extent, where large sums of money, expended in forming open drains in the swamp itself, would leave it but little improved.

In the laying out of drains the first point to be determined is the place of outfall, which should always afford a free and clear outlet to the drains, and must necessarily be at the lowest point of the land to be drained. The next point to be determined is the position of the minor drains; in the laying out of which the surface of each field must be regarded as being made up of one or more planes, as the case may be, for each of which the drains should be laid out separately. Level lines are to be set out a little below the upper edge of each of these planes, and the drains must then be made to cross these lines at right angles. By this means the drains will run in the line of the greatest slope, no matter how distorted the surface of the field may be. All the minor drains should be made to discharge into mains or submains, and not directly into an open ditch or water-course. As a general rule there should be a main to receive the waters of the minor drains from every 5 acres.

The advantages of drainage are obvious. In the first place it allows the soil to be brought into a more suitable condition for the growth of plants, aiding in producing the finely-divided and porous state by which the roots and rootlets can spread themselves at will in order to obtain the needed supplies of food, air, and moisture. It also allows the sun's rays to produce their full effect on the soil and plants without being robbed of great part of it by the stagnant water.
Research Draining

HERBARIUM

An herbarium, or Hortus Siccus is , a collection of dried plants systematically arranged. Herbariums were popular among the Victorians, and a Victorian text describes the process for collecting specimens thus:

'The specimens should be collected in dry weather, and carried home in a japanned tin-box or vasculum, a small pocket-box being desirable, however, for mosses and small plants. Very delicate specimens should be at once placed in a small field-book of unsized blotting-paper carried tightly strapped between suitable boards, At home they are carefully arranged upon bibulous paper, and pressed between smoothly planed deal boards either by putting weights upon the boards or by using a screw-press. The paper is changed every day or two, as they are found to part with their moisture more or less freely.

Succulent plants (such as stone-crops) should be killed by immersion in boiling water, and left for some time to drain, before pressing. If the stem be thick and woody, or if the flower be thick and globular, as in the thistle, one half may be cut away without depriving it of its character. When the process of desiccation has been completed specimens are fastened upon stiff paper with a mixture of gum-tragacanth and gum-arabic, or thin glue, or with slips of gummed paper, or a needle and thread. To preserve the specimens from the ravages of insects, camphor should be placed in the cabinet and frequently renewed.'
Research Herbarium

PLATEAU

A plateau or tableland generally denotes a large stretch of highland which is practically the same height above sea-level, and which descends on all sides to lower ground. Some plateaux, however, such as those of Tibet and Bolivia, that are fringed by high mountain ranges which tower above the plateau level, are known as intermont plateaux. Sometimes they are so completely enclosed as to have no outlet to the sea.

A plateau might be regarded as an elevated plain, but there is often a great difference between the surface of a plain and that of a plateau. As a plateau is high, rivers are swift and carve deep, narrow valleys instead of the broad, open valleys of the lower rivers of the plains. Such plateau areas as Wales and the Highlands of Scotland, are broken by deep, narrow valleys, and are termed dissected plateaux. On reaching the top of such an area one has a long view of a series of flat-topped mountain ridges. These ridges are all of approximately the same height, and if one imagines the clouds descending until they touched one ridge, then almost every other ridge would be similarly cloud-capped. Other good examples of plateaux are Tibet in Asia, the Ecuador and Bolivian plateaux in South America, and nearly the whole of the continent of Africa.

The Deccan of India is a plateau that has been tilted so that the western edge is much higher than the eastern edge, and all the main rivers drain eastwards. In many instances plateaux are formed by the denudation or wearing down of higher mountainous areas. Ultimately, such areas may become so low that they are nearly plains, i.e. peneplains, such as the land around Hudson Bay. Millions of years ago lava was forced up through cracks in the earth's crust, and spread out over the land in great sheets which have since hardened to form plateaux of basalt.

Two well-known examples of such plateaux are in Antrim (Ireland), and on the Deccan of India to the east of Bombay. Many of the most extensive areas of plateaux in the world are composed of very hard old rock. The Guiana Highlands, most of Africa, Arabia, the Deccan of India, and the West Australian plateaux are all composed of rocks of similar age. The ancient plateau lands are principally valuable for their minerals, such as the gold of Western Australia; the iron and manganese of the Brazilian Highlands; the gold, copper, and diamonds of the African plateau; and the gold of the Lena plateau in Siberia. Where plateaux are found in tropical areas they are important because, being cooler than the neighbouring lowlands, they offer greater possibilities for successful European settlement and development. The highlands of Brazil, Kenya, and Tanganyika are illustrations of this. Much of the tropical plateau area is covered by savannah grasslands. Most of these areas are not yet developed, but offer possibilities for the production of a large variety of both animal and vegetable products when communications have been developed and further settlement has taken place.
Research Plateau

WILLIAM KILLIGREW

Sir William Killigrew was an English dramatist. He was born in 1606 and died in 1695. He was gentleman-usher to Charles I and suffered for his adherence to the royal cause. He was ruined by his unsuccessful attempts to drain the Lincolnshire fens.
Research William Killigrew

ATRIUM

Research Atrium

CATHETERS

A catheter is a tube that is inserted into a hollow organ of the body in order to drain or introduce fluids. A urinary catheter is inserted into the bladder through the urethra to relieve obstruction to the flow of urine. Cardiac catheters are used to measure blood pressure in the heart. Similar catheters are used to inject radio- opaque substances into blood vessels for X-ray examination.
Research Catheters

CRANIAL SINUSES

The cranial sinuses are air-filled cavities within the skull bones, joined by openings to the main airway inside the nose. Four pairs of sinuses (the frontal, the maxillary, the sphenoidal, the ethmodial) drain into the nasal cavities. The maxillary are the largest sinuses. They extend from the floor of the orbits to the roots of the upper teeth. The sinuses are lined with mucous membrane which is commonly aggravated by pollution leading to an excessive release of mucous.
Research Cranial Sinuses

DEEP CERVICAL CHAIN

The deep cervical chain of lymph nodes are located on each side of the neck beneath the sternocleidomastoid muscle. These chains of lymph nodes drain and filter lymph from the thyroid gland, the larynx, the trachea, and the upper portion of the esophagus. Because they lie deep within the body tissue, they are difficult to assess through palpation.
Research Deep Cervical Chain

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