How to use Impurities in a sentence
All impurities do not act in a similar way.
This result he considered to be due, not to any removal of impurities, but to an actual splitting-up of the yttrium molecule into its constituents, and he ventured to draw the provisional conclusion that the so-called simple bodies are in reality compound molecules, at the same time suggesting that all the elements have been produced by a process of evolution from one primordial stuff or "protyle."
Ferric hydrate, iron soaps and all insoluble impurities are precipitated.
Taylor bag filters are generally used for clearing the melted liquor of its mechanical impurities.
The slight variations in specific gravity are due to the presence of small amounts of arsenic, sulphur or tellurium, or to enclosed impurities.Advertisement
Thus so-called coloured-gold deposits may be produced by the judicious introduction of suitable impurities.
In small works the cupellation is finished in one furnace, and the resulting low-grade silver fined in a plumbago crucible, either by overheating in the presence of air, or by the addition of silver sulphate to the melted silver, when air or sulphur trioxide and oxygen oxidize the impurities.
The slag and metal produced are then run off and the latter is cast into bars; these are in general contaminated with iron, arsenic, copper and other impurities.
The slime so obtained consists of finely divided gold and silver (5-5 0%), zinc (30-60%), lead (io%), carbon (io%), together with tin, copper, antimony, arsenic and other impurities of the zinc and ores.
Filtration in the chemical laboratory is commonly effected by the aid of a special kind of unsized paper, which in the more expensive varieties is practically pure cellulose, impurities like feric oxide, alumina, lime, magnesia and silica having been removed by treatment with hydrochloric and hydrofluoric acids.Advertisement
As regards its constitution, it has been given at different times the formulae NI 3, NHI 2, NH 2 I, N 2 H 3 I 3, &c., these varying results being due to the impurities in the substance, owing to the different investigators working under unsuitable conditions, and also to the decomposing action of light.
Poisoning by caustic soda is rare, but occasionally it takes place by swallowing soap lees (sodium carbonate), which may contain some impurities of caustic soda.
The Cumberland graphite, which is especially suitable for pencils, contains about 12% of impurities.
If the original solution contained the chlorides of magnesium or calcium or sulphate of potassium all impurities remain in the mother-liquor (the sulphur as KHS04), and can be removed by washing the precipitate with strong hydrochloric acid.
The purified carbonate (which still contains most of the chloride of the raw material and other impurities) is known as "pearl ashes."Advertisement
The intense heat generated tends to liberate many impurities which are carried away in the slag.
The various kinds of brown and yellow ochre are mixtures of limonite with clay and other impurities; whilst in umber much manganese oxide is present.
The temperature of the condenser is so regulated as to bring about the condensation of the nitric acid only, which runs out at the bottom of the pipe, whilst any uncondensed steam, nitrogen peroxide and other impurities pass into a Lunge tower, where they meet a descending stream of water and are condensed, giving rise to an impure acid.
The individual and collective influence of the several impurities which occur in the product of the Heroult cell is still to seek, and the importance of this inquiry will be seen when we consider that if cast iron, wrought iron and steel, the three totally distinct metals included in the generic name of "iron" - which are only distinguished one from another chemically by minute differences in the proportion of certain non-metallic ingredients - had only been in use for a comparatively few years, attempts might occasionally be made to forge cast iron, or to employ wrought iron in the manufacture of edge-tools.
Thus the distinctive work of the second and third periods is freeing the metal from mechanical impurities by fusion.Advertisement
In 1856 Bessemer not only invented his extraordinary process of making the heat developed by the rapid oxidation of the impurities in pig iron raise the temperature above the exalted melting-point of the resultant purified steel, but also made it widely known that this steel was a very valuable substance.
Impurities.-The properties of iron and steel, like those of most of the metals, are profoundly influenced by the presence of small and sometimes extremely small quantities of certain impurities, of which the most important are phosphorus and sulphur, the former derived chiefly from apatite (phosphate of lime) and other minerals which accompany the iron ore itself, the latter from the pyrite found not only in most iron ores but in nearly all coal and coke.
If the pig iron is to follow path 2, the purification which converts it into wrought iron or steel consists chiefly in oxidizing and thereby removing its carbon, phosphorus and other impurities, while it is molten, either by means of the oxygen of atmospheric air blown through it as in the Bessemer process, or by the oxygen of iron ore stirred into it as in the puddling and Bell-Krupp processes, or by both together as in the open hearth process.
In the former case there is no later chance to remove sulphur, a minute quantity of which does great harm by leading to the formation of cementite instead of graphite and ferrite, and thus making the cast-iron castings too hard to be cut to exact shape with steel tools; in the latter case the converting or purifying processes, which are essentially oxidizing ones, though they remove the other impurities, carbon, silicon, phosphorus and manganese, are not well adapted to desulphurizing, which needs rather deoxidizing conditions, so as to cause the formation of calcium sulphide, than oxidizing ones.
The ultimate source of the oxygen may be the air, as in the Bessemer process, or rich iron oxide as in the puddling process, or both as in the open-hearth process; but in any case iron oxide is the chief immediate source, as is to be expected, because the oxygen of the air would naturally unite in much greater proportion with some of the great quantity of iron offered to it than with the small quantity of these impurities.Advertisement
If the initial quantity of phosphorus or sulphur is large, or if the removal of these impurities is to be made very thorough, the dephosphorizing or the desulphurizing slagging off may be repeated.
Generally speaking this salt, which may contain up to 15% of impurities, goes into commerce just as it is, but in some cases it is taken first to the refinery, where it either is simply washed and then stove-dried before being sent out, or is dissolved in fresh water and then boiled down and crystallized like white salt from rock-salt brine.
The salt of the " salines du midi " of the south-east of France is far purer, containing about 5% of impurities.
Sometimes, to get rid of these impurities, the brine is treated in a large tub-`(bessoir) with lime; on settling it becomes clear and colourless, but the dissolved lime forms a skin on its surface in the pan, retards the evaporation and impedes the crystallization.
The remaining silicates and aluminates present, and ferric oxide and magnesia, if existing in the moderate quantities which are usual in Portland cement of good quality, are of minor importance and may be regarded as little more than impurities.
This may be almost chemically pure, when it is generally used for Keene's cement; or it may contain smaller or greater quantities of impurities, in which case it is suitable for the preparation of cements of the plaster of Paris class.
This roaster-acid is, however, of less value than the pot-acid, as it contains more impurities.
A number of secondary reactions, however, occur, owing partly to the excess of calcium carbonate and coal and partly to the impurities present, so that the solid product of the process, which is called " black-ash," has a somewhat complicated composition.
In spite of all precautions a certain quantity of impurities is always formed, but this should be kept down as much as possible by strictly watching the temperature in the vats and by taking care that the black-ash in the wet state is never exposed to the air.
The principal impurities of crude vat-liquor are sodium hydrate and sulphide, the latter of which always leads to the formation of soluble double sulphur salts of sodium and iron.
The other impurities are of minor importance.
The mother-liquor, drained from the soda-crystals, on boiling down to dryness yields a very white, but low-strength soda-ash, as the soluble impurities of the original soda-ash are nearly all collected here; it is called " mother-alkali."
There was no satisfactory cleaning of the streets or draining of the sub-soil, and the harbour was rendered visibly foul by the impurities of the town.
The metal as obtained by industrial methods rarely contains more than about 99-99.5% of nickel, the chief impurities being copper, iron, cobalt, silicon and carbon.
An immense mass of material has been collected on the subject of vapour-pressures and densities, the greater part of which will be found in Winkelmann's Handbook, in Landolt's and Bornstein's Tables, and in similar compendiums. The results vary greatly in accuracy, and are frequently vitiated by errors of temperature measurement, by chemical impurities and surface condensation, or by peculiarities of the empirical formulae employed in smoothing the observations; but it would not be within the scope of the present article to discuss these details.
We have seen how closely the serpent is associated with water generally (§ 5 seq.), and since we meet with the belief that sources will dry up when the serpent-occupant is killed (Bechuanas, Zulus), or that they will resent impurities thrown into their springs by causing storms (tribes of the Hindu-Kush), it is not surprising to find elaborate precautions for the propitiation of such powerful beings.
The commercial acid is usually yellow in colour and contains many impurities, such as traces of arsenic, sulphuric acid, chlorine, ferric chloride and sulphurous acid; but these do not interfere with its application to the preparation of bleaching powder, in which it is chiefly consumed.
The delay attendant on this method of purification is avoided by treating the crude oil with 1 to 2% of a somewhat strong sulphuric acid, which chars and carries down the bulk of the impurities.
Since all sulphuretted copper ores (and these are of the most economic importance) are invariably contaminated with arsenic and antimony, it is necessary to eliminate these impurities, as far as possible, at a very early stage.
The impurities contained in coarse-copper are mainly iron, lead, zinc, cobalt, nickel, bismuth, arsenic, antimony, sulphur, selenium and tellurium.
The chief impurities are basic salts of iron, free iron, graphite, and sometimes silica, antimony and iron arsenates.
Washing removes some of these impurities, but some copper always passes into the slimes.
The principles have long been known on which is based the electrolytic separation of copper from the certain elements which generally accompany it, whether these, like silver and gold, are valuable, or, like arsenic, antimony, bismuth, selenium and tellurium, are merely impurities.
Silver and other insoluble impurities collected at the bottom of the trough up to the level of the lower side-tube, and were then run off through a plug in the bottom into settling tanks, from which they were removed for metallurgical treatment.
The electrical pressure required to force a current of this intensity through the solution, and to overcome a certain opposing electromotive force arising from the more electro-negative impurities of the anode, depends upon the composition of the bath and of the anodes, the distance between the electrodes, and the temperature, but under the usual working conditions averages o-3 volt for every pair of electrodes in series.
Its impurities are lead, oxalic acid, lime and potassium tartrate.
The word, according to his interpretation, signifies the baptism of Metis, or of fire, and is, therefore, connected with the impurities of the Gnostic Ophites.
Various impurities, such as copper, antimony and sulphur, go into the lead button, so that the result is generally too high.
The most accurate method for the determination of lead in ores is the gravimetric method, in which it is weighed as lead sulphate after the various impurities have been separated.
As the wire always contains impurities, the absolute amount of iron in the wire must be determined and the correction made accordingly.
It is then examined by a native expert (purkhea) as to impurities, colour, fracture, aroma and consistence.
When the rock has been separated from the amalgam by a washing operation, the quicksilver is recovered by distillation in an iron retort, and the remaining crude retortsilver melted into bars and shipped to a refinery, which removes the impurities, the leading one of which is copper.
To eliminate these impurities, electrolytic methods have been devised; of these that of Moebius is the most important and will be described in detail.
The presence of these enclosed impurities impairs the transparency of crystals.
The crude phosphorus is purified by melting under water and then filtering through animal black and afterwards through chamois leather, or by treating it, when molten, with chromic acid or a mixture of potassium bichromate and sulphuric acid; this causes the impurities to rise to the surface as a scum which can be skimmed off.
Deep wells owe their comparative immunity from pollution to the circumstances that the larger quantity of water yielded renders it worth while to pump that water and convey it by pipes from comparatively unpolluted areas; and that any impurities in the water must have passed through a considerable depth, and by far the larger part of them through a great length of filtering material, and must have taken so long a time to reach the well that their organic character has disappeared.
As such strainers were further improved, by sorting the sand and gravel, and using the fine sand only at the surface, better clarification of the water was obtained; but chemical analysis indicated, or was at the time thought to indicate, that that improvement was practically confined to clarification, as the dissolved impurities in the water were certainly very little changed.
These difficulties were mostly caused by the solid impurities contained in the burner-gases in the shape of flue-dust, especially the arsenic, which after a short time rendered the contact substance inactive, in a manner not as yet entirely understood.
At this point in the manufacturing process the gas has already undergone some important changes in its composition, but there yet remain impurities which must be removed, these being ammonia, sulphuretted hydrogen, carbon disulphide and carbon dioxide.
The contents of the third box, being mostly composed of slaked lime, take up sulphuretted hydrogen forming calcium sulphide, and practically remove the remaining impurities, the outlet gas showing 20 grains of sulphuretted hydrogen and 8 grains of carbon disulphide per Ioo cub.
It will be noticed that in the earlier stages the quantity of sulphur impurities is actually increased between the purifiers - in fact, the greater amount of sulphiding procures the ready removal of the carbon disulphide, - but it is the carbon dioxide in the gas that is the disturbing element, inasmuch as it decomposes the combinations of sulphur and calcium; consequently it is a paramount object in this system to prevent this latter impurity finding its way through the first box of the series.
The chief impurities are copper and ferric sulphates; the former may be removed by adding scrap iron, which precipitates the copper; the latter is eliminated by recrystallization.
Other impurities such as zinc and manganese sulphates are more difficult to remove, and hence to prepare the pure salt it is best to dissolve pure iron wire in dilute sulphuric acid.
Since the methods of preparing the vegetable and animal fats are comparatively crude ones, they usually contain certain impurities of one kind or another, such as colouring and mucilaginous matter, remnants of vegetable and animal tissues, &c. For the most part these foreign substances can be removed by processes of refining, but even after this purification they still retain small quantities of foreign substances, such as traces of colouring matters, albuminoid and (or) resinous substances, and other foreign substances, which remain dissolved in the oils and fats, and can only be isolated after saponification of the fat.
If care be exercised in the process of rendering animal oils and fats or expressing oils in the cold, the products are, as a rule, sufficiently pure to be delivered to the consumer, after a preliminary settling has allowed any mucilaginous matter, such as animal or vegetable fibres or other impurities, and also traces of moisture, to separate out.
The acid not only takes up water, but it acts on the suspended impurities, carbonizing them to some extent, and thus causing them to coagulate and fall down in the form of a flocculent mass, which carries with it mechanically other impurities which have not been acted upon.
In most cases the purification consisted in removing the free fatty acids from rancid oils and fats, the caustic soda forming a soap with the fatty acids, which would either rise as a scum and lift up with it impurities, or fall to the bottom and carry down impurities.
There is still a wide field open for the application of proper processes for the removal of impurities and colouring matters without running the risk of attacking the oil or fat itself.
As the impurities increase in amount the clay rocks pass gradually into argillaceous sands and sandstones, argillaceous limestones and dolomites, shaly coals and clay ironstones.
It is fine, tenacious and bright red, and represents the insoluble and thoroughly weathered impurities which are left behind when the calcareous matter is removed in solution by carbonated waters.
In a legalized framework, drugs would not contain adulterants and impurities, and dosage would be accurately quantified.
Explore changes of grain boundary energy arising from segregation of impurities.
On top of this trees will absorb many impurities in the air, for example particles of toxic metals, such as lead.
Jasper also belongs to this group, and contains impurities which cause heavy pigmentation.
Since it contained at least 40 percent impurities when manufactured, sarin produced at Al Muthanna had a short shelf life.
I doped silicon with several different group I and II impurities and measured their influence on the electrical and optical properties.
The impurities then float to the top of the metal forming slag.
Further impurities are removed using aqueous sodium hydroxide to neutralize free acids and steam which removes volatile compounds.
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For Proof coins only virgin materials are used so that the cast metal is free from impurities.
Impurities are often present, especially when the resin dropped on to the ground, so that the material may be useless except for varnish-making, whence the impure amber is called firniss.
It may confidently be asserted that, of insects which directly or indirectly affect the welfare of man, Diptera form the vast majority, and it is a moot point whether the good effected by many species in the rapid clearing away of animal and vegetable impurities, and in keeping other insect enemies in check, counterbalances the evil and annoyance wrought by a large section of the Order.
Owing to this circumstance it is impossible to " fit " or in any way purify soft soap, and all impurities which go into the pan of necessity enter into the finished product.
In Mexico filters filled with dry powdered megass have been found very efficient for removing the large quantity of impurities contained in the juice expressed from the very vigorous but rank canes grown in that wonderfully fertile country, but unless constant care is taken in managing them, and in changing them at the proper time, there is great risk of inversion taking place, with consequent loss of sugar.
In practice, however, we never have to deal with pure zinc minerals, but with complex mixtures, which must first of all be subjected to mechanical operations, to remove at least part of the gangue, and if possible also of the heavy metallic impurities (see ORE-Dressing).
From these and other considerations it is obvious that (I) the electrolyte must be such as will freely dissolve the metal to be refined; (2) the electrolyte must be able to dissolve the major portion of the anode, otherwise the mass of insoluble matter on the outer layer will prevent access of electrolyte to the core, which will thus escape refining; (3) the electrolyte should, if possible, be incapable of dissolving metals more electro-negative than that to be refined; (4) the proportion of soluble electro-positive impurities must not be excessive, or these substances will accumulate too rapidly in the solution and necessitate its frequent purification; (5) the current density must be so adjusted to the strength of the solution and to other conditions that no relatively electro-positive metal is deposited, and that the cathode deposit is physically suitable for subsequent treatment; (6) the current density should be as high as is consistent with the production of a pure and sound deposit, without undue expense of voltage, so that the operation may be rapid and the "turnover" large; (7) the electrolyte should be as good a conductor of electricity as possible, and should not, ordinarily, be altered chemically by exposure to air; and (8) the use of porous partitions should be avoided, as they increase the resistance and usually require frequent renewal.
When kathode rays strike certain substances, they emit a phosphorescent light, the spectroscopic investigation of which shows interesting effects which are important especially as indicating the influence of slight admixtures of impurities on the luminescence.
It follows, therefore, except for mechanical losses, that one charge of cryolite lasts indefinitely, that the sodium and other impurities in it are not liable to contaminate the product, and that only the alumina itself need be carefully purified.
If the carbon-content is not to be raised materially, this manganese is added in the form of preheated lumps of " ferro-manganese," which contains about 80% of manganese, 5% of carbon and 15% of iron, with a little silicon and other impurities.
The sewage of the city and other impurities were for centuries allowed to pollute the bay, but the extent to which the harbour was thereby filled up has been exaggerated.
Who is there, that if his hands do not reek with human blood, is not soiled with foul impurities?
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The most valuable gold has to be refined by fire - to get rid of its impurities.
Before a new product can reach the customer it has to be exhaustively tested for tiny traces of impurities.
Water filters to reduce lead, chlorine, and other impurities in ice and drinking water.
Diamond color is affected by chemical impurities or structural defects in its crystal lattice.
Combinations of a variety of impurities and structural imperfections create different diamond colors including yellow, pink, blue, red, green, brown, and other hues.
The purest form of gold is the 24 karat, which is 99.9 percent gold with some possible impurities.
Oatmeal is very soothing to the skin, and this oatmeal mask helps to draw out the impurities, as well as decrease swollen, red areas around pimples.
This tea is created to help cleanse impurities from your body such as food additives, caffeine and alcohol.
Make sure you drink plenty of water to flush out impurities, and embark upon a thorough cleansing, toning and moisturising regime.
Impurities or additives, which make the heroin darker, can include things like sugar, starch, powdered milk, strychnine, other poisons and more drugs.
It is then sorted and washed with hot water and organic soap to remove impurities such as dirt, grease and dried sweat.
Impurities account for between 30 and 60 percent of the total fleece weight.
This can be especially important during exercise, when pores open and the body is trying to rid itself of impurities through sweat.
Most are caused by impurities in the urine sample, failing to read the test instructions, using an expired pregnancy test, or trying to take the test too early.
Since capsules can be expensive and in many case quite "unnatural" with the added risk of potential impurities (Chinese imports have been found to cause quite a few scares lately,) we'll focus on the functional food angle.
Pure pressing filters out impurities and excess sugars, and leaves only the best juice for our consumers.
The reasons for purchasing HEPA filtered air purifies are usually inspired by a desire to filter out air pollutants in a home such as dust mites and other impurities that can create health concerns.
Persons with compromised immune systems may use the devices to purify their surroundings by eliminating disease-causing bacteria and other impurities from the air that may adversely affect their health.
Because the tinting is caused by inclusions rather than impurities, black diamonds are usually opaque, though translucent or semi-transparent specimens are considered extremely valuable.
While these other elements might be considered impurities, they actually produce a rainbow of diamond colors.
Use a clay bar, which you can buy at auto supply shops like AutoGeek.net or Chemical Guys, to remove impurities that remain on your car's clear coat after washing.
The goal of the diet is to rest the digestive tract, cleanse the system of impurities, mobilize and eliminate toxins stored in various areas of the body, and burn excess fat stores.
During this time, supporters claim that the body will cleanse itself and many of the unwanted build-ups of impurities and toxins will be eliminated from the body.
It's a much better idea to think about the Lemonade Diet under its other name, Master Cleanse Diet, because the real idea behind the diet is cleaning impurities from the body, not losing weight.
During the first phase of the diet plan impurities are flushed from your body.
A detoxification fasting diet is often touted as a great way to rid your body of impurities while losing weight.
Experts recommend using filtered water to remove potential impurities.
Impurities diminish the taste and can add off, metallic flavors to coffee.
Drinking at least eight to ten glasses of water per day is also recommended to help flush impurities from your body; this may have a direct effect on acne as well.
At times, hard-working skin needs help purging impurities and blockages in the pores.
Since acne begins under the skin, a good detox may help eradicate some of these pimple-causing impurities.
The superb nondrying clay and seaweed mask aims to detoxify and remove any impurities from skin, leaving it glowing and radiant.
Use gentle but firm pressure to remove the impurities in your pores.
Not only does it exfoliate dead skin cells and eliminate impurities, it also contributes the long term health of the facial skin.
That fresh faced look you get after a moderate to strenuous workout is your body's way of ridding impurities, and you can bet that same glow will stick around after you've cooled off if you make exercise a regular part of your lifestyle.
Deep clean - A mask should clean your skin well, by reaching down into pores and pulling out any impurities that lead to breakouts.
Egg whites will pull out the impurities from under the skin.
The spa may administer a microdermabrasion treatment to remove dead skin cells and slough away impurities from the top layers of your skin.
This foaming cleanser removes dirt and impurities from the skin without dryness, redness, or irritation.
This mask features a formula with glacial clay to draw out impurities and excess oils to refine pores for exceptional clarity and a revitalized appearance.
Skin Balancing Cleanser gently removes makeup, impurities, and excess oil without dryness.
Micro-Smoothing Wet Cleansing Towelettes, made from a special embossed fabric that completely removes impurities and makeup, leaving a clean, fresh scent.
Radiant Smoothing Cream Cleanser removes all traces of makeup and impurities.
This is largely due to the improved methods of preparing the rubber practised by the planters of Ceylon and Malaya, which lead to the exclusion of the impurities usually found in " wild " rubber.
This has been ascribed by some to the presence in " wild " rubber of certain impurities derived either from the latex or introduced during the preparation of the rubber which are thought to enhance the physical properties of the caoutchouc. It is more probable, however,.
The rubber is usually dark in colour and is often contaminated with proteid impurities derived from the latex.
As the removal of the impurities of the latex is one of the essential points to be aimed at, it was thought that the use of a centrifugal machine to separate the caoutchouc as a cream from the watery part of the latex would prove to be a satisfactory process.
The probabilities are that in the end the production of a rubber as nearly as possible free from water and impurities and of constant composition will be realized as best meeting the requirements of the modern manufacturer.
The lead is melted down slowly, when the impurities separate in the form of a scum (dross), which is easily removed.
Owing to impurities contained in the materials from which glasses are made, accidental coloration or discoloration is often produced.
The raw materials are selected with great care to assure chemical purity, but whereas in most glasses the only impurities to be dreaded are those that are either infusible or produce a colouring effect upon the glass, for optical purposes the admixture of other glass-forming bodies than those which are intended to be present must be avoided on account of their effect in modifying the optical constants of the glass.
Many electrolytic methods have been proposed for the purification of sugar; in some of them soluble anodes are used for a few minutes in weak alkaline solutions, so that the caustic alkali from the cathode reaction may precipitate chemically the hydroxide of the anode metal dissolved in the liquid, the precipitate carrying with it mechanically some of the impurities present, and thus clarifying the solution.
Thus prepared it has a fineness of 800-960, the chief impurities usually being iron and lead.
Other undesirable impurities are the platinum metals, special treatment being necessary when these substances are present.
The dry process is more frequently practised, for the easy reducibility of the oxide and sulphide, together with the low melting-point of the metal, renders it possible to effect a ready separation of the metal from the gangue and impurities.
A dry method of purification consists in a liquation on a hearth of peculiar construction, which occasions the separation of the unreduced bismuth sulphide and the bulk of the other impurities.
A greater hardness is due to the presence of earthy impurities.
The purity of the carbide entirely depends on the purity of the material used in its manufacture, and before this fact had been fully grasped by manufacturers, and only the purest material obtainable employed, it contained notable quantities of compounds which during its decomposition by water yielded a somewhat high pro portion of impurities in the acetylene generated from it.
Innumerable forms of filters made with these and other materials were put on the market, and were extolled as removing impurities of every kind from water, and as affording complete protection against the communication of disease.
But whatever merits they had as clarifiers of turbid water, the advent of bacteriology, and the recognition of the fact that the bacteria of certain diseases may be water-borne, introduced a new criterion of effectiveness, and it was perceived that the removal of solid particles, or even of organic impurities (which were realized to be important not so much because they are dangerous to health per se as because their presence affords grounds for suspecting that the water in which they occur has been exposed to circumstances permitting contamination with infective disease), was not sufficient; the filter must also prevent the passage of pathogenic organisms, and so render the water sterile bacteriologically.
All commercial iron and steel contain more or less of both these impurities, the influence of which is so strong that a variation of o o, %, i.e.
Many health care practitioners feel that the human body is able to complete detoxification without a special diet; the kidneys, skin, lungs and liver remove impurities from the body in a healthy person.
Impurities render the mineral grey, greenish or reddish, bituminous matter being often present in the massive varieties.
The impurities occasionally present in commercial citric acid are salts of potassium and sodium, traces of iron, lead and copper derived from the vessels used for its evaporation and crystallization, and free sulphuric, tartaric and even oxalic acid.
The soap is from this again grained off or salted out, and the underlye so thrown down carries with it coloured impurities which may have been in the materials or which arise from contact with the boiler.
Even if he be an inhabitant of the sacred city he must traverse it once in the year to free himself from the impurities and sins contracted within the holy precincts.
It is therefore necessary that the solution should be free from metals which may vitiate the results, or special precautions taken by which the impurities are rendered harmless.
It is to be noted that although the correlation of melting-point with constitution has not been developed to such an extent as the chemical significance of other physical properties, the melting-point is the most valuable test of the purity of a substance, a circumstance due in considerable measure to the fact that impurities always tend to lower the melting-point.
In the deposition of gold the colour of the deposit is influenced by the presence of impurities in the solution; when copper is present, some is deposited with the gold, imparting to it a reddish colour, whilst a little silver gives it a greenish shade.
The second operation is the coagulation of the albumen, and the separation of it with other impurities from the Maceration or Imbibition.
Every twenty-four hours or so the flow of juice may be conveniently stopped, and, after all the impurities have subsided, the superincumbent clear liquor may be decanted by a cock placed at the side of the cone for the purpose, and the vessel may be washed out.
These separators are carefully protected by non-conducting cement and wood lagging, and are closed at the top to prevent loss of heat; and they will run for many hours without requiring to be changed, the duration of the run depending on the quality of the liquor treated and amount of impurities therein.
In diffusion plants the milk of lime is added, in proper proportion, in the cells of the diffusion battery, and the chips or slices themselves act as a mechanical filter for the juice; while in the Sandwich Islands coral-sand filters have been employed for some years, in addition to the chips, to free the juice from impurities held in mechanical suspension.
Its chief uses are in glass-making to promote fluidity, in metallurgy to oxidize impurities, as a constituent of gunpowder and in pyrotechny; it is also used in the manufacture of nitric acid.
A bath, even of very impure zinc, is allowed to stand at about the temperature of the melting-point of the metal for forty-eight or more hours, whereupon the more easily oxidizable impurities can be largely removed in the dross at the top, the heavier metals such as lead and iron settling towards the bottom.
It is then separated in a centrifugal machine, the low melting-point impurities are removed by means of hot water, and the residue is finally hot-pressed.
The first portion of the distillate brings over the gases dissolved in the water, ammonia and other volatile impurities, and is consequently rejected; scarcely two-fifths of the entire quantity of water can be safely used as pure distilled water.
It is necessary to remove as completely as possible any lead, tin, bismuth, antimony, arsenic and tellurium, impurities which impair the properties of gold and silver, by an oxidizing fusion, e.g.
Phosphuretted hydrogen, one of the most important impurities, which has been blamed for the haze formed by the combustion of acetylene under certain conditions, is produced by the action of water upon traces of calcium phosphide found in carbide.
The only one of the impurities which offers any difficulty in removal is the phosphuretted hydrogen.
In some cases the operation of filtration is performed for the sake of removing impurities from the filtrate or liquid filtered, as in the purification of water for drinking purposes; in others the aim is to recover and collect the solid matter, as when the chemist filters off a precipitate from the liquid in which it is suspended.
Crude sulphur, as obtained from kilns, contains about 3% of earthy impurities, and consequently needs refining.
In this way curd, mottled or marbled soap is formed, and such mottled appearance was formerly highly valued as an indication of freedom from excess of water or other adulteration, because in fitted soaps the impurities are either washed out or fall to the bottom of the mass in cooling.
Solid impurities speedily become crushed, and are carried away by the water, while the rubber takes the form of an irregular sheet perforated by numerous holes.
Of the impurities, most of the copper, nickel and copper, considerable arsenic, some antimony and small amounts of silver are removed by liquation.
Of these the Pattinson process has become subordinate to the Parkes process, as it is more expensive and leaves more silver and impurities in the market lead.
The presence of ordinary impurities usually tends to diminish the permeability, though, as will appear later, the addition of small quantities of certain other substances is sometimes advantageous.
Of the impurities of the ore the wolframite (tungstate of iron and manganese) is the most troublesome, because on account of its high specific gravity it cannot be washed away as gangue.
The original top stratum is the purest, and each succeeding lower stratum has a greater proportion of impurities; the lowest consists largely of a solid or semi-solid alloy of tin and iron.
On its thoroughness depends the removal of small quantities of products other than the nitrates, for instance, some sulphates and products from impurities contained in the original cellulose.
In practice, however, we never have to deal with pure zinc minerals, but with complex mixtures, which must first of all be subjected to mechanical operations, to remove at least part of the gangue, and if possible also of the heavy metallic impurities.
The specific effects of different impurities on the physical properties of zinc have only been imperfectly studied.
The crystals are collected, washed, pressed and recrystallized, whereby the impurities are easily removed.
On passing a current of electricity, of which the volume and pressure are adjusted to the conditions of the electrolyte and electrodes, the anode slowly dissolves, leaving the insoluble impurities in the form of a sponge, if the proportion be considerable, but otherwise as a mud or slime which becomes detached from the anode surface and must be prevented from coming into contact with the cathode.
Soluble impurities which are more electro-negative than the metal under treatment must, if present, be removed by a preliminary process, and the voltage and other conditions must be so selected that none of the more electro-positive metals are co-deposited with the metal to be refined.
All remaining impurities, including the excess of oxygen, can then be taken out of the gas by Sir James Dewar's ingenious method of absorption with charcoal cooled in liquid air.
As quarried or mined free sulphur is always contaminated with limestone, gypsum, clay, &c.; the principle underlying its extraction from these impurities is one of simple liquation, i.e.
In 1806 Sir Humphry Davy proved that the formation of acid and alkali when water was electrolysed was due to saline impurities in the water.