The atomic weight of cadmium has been revised by G.
Soc., 1905, 27, p. 222), by determinations of the ratio of cadmium chloride to silver chloride, and of the amount of silver required to precipitate cadmium chloride.
The black films of tin, lead and cadmium dissolve at once in the acid, the lead film being also soluble in bleaching-powder.
Distillable at red heats: cadmium, alkali metals, zinc, magnesium.
For certain concentrated solutions the transport number is found to be greater than unity; thus for a normal solution of cadmium iodide its value is I 12.
Cadmium is a white metal, possessing a bluish tinge, and is capable of taking a high polish; on breaking, it shows a distinct fibrous fracture.
Cadmium sulphate, CdSO 4, is known in several hydrated forms; being deposited, on spontaneous evaporation of a concentrated aqueous solution, in the form of large monosymmetric crystals of composition 3CdSO 4.8H 2 O, whilst a boiling saturated solution, to which concentrated sulphuric acid has been added, deposits crystals of composition CdSO 4 4H 2 0.
The atomic weight of cadmium was found by 0.
Thus, diminishing the concentration of the cadmium iodine solution from normal to one-twentieth normal changes the transport number from I 12 to o 64.
CADMIUM (symbol Cd, atomic weight I12.4 (0=16)), a metallic element, showing a close relationship to zinc, with which it is very frequently associated.
Cadmium does not occur naturally in the uncombined condition, and only one mineral is known which contains it in any appreciable quantity, namely, greenockite, or cadmium sulphide, found at Greenock and at Bishopton in Scotland, and in Bohemia and Pennsylvania.
The cadmium molecule, as shown by determinations of the density of its vapour, is monatomic. The metal unites with the majority of the heavy metals to form alloys; some of these, the so-called fusible alloys, find a useful application from the fact that they possess a low melting-point.
Cadmium vapour decomposes water at a red heat, with liberation of hydrogen, and formation of the oxide of the metal.
Cadmium hydroxide, Cd(OH) 2, is obtained as a white precipitate by adding potassium hydroxide to a solution of any soluble cadmium salt.
The chloride,CdC1 2, bromide,CdBr 2, and iodide,Cdl2,arealsoknown, cadmium iodide being sometimes used in photography, as it is one of the few iodides which are soluble in alcohol.
Cadmium sulphide, CdS, occurs naturally as greenockite (q.v.), and can be artificially prepared by passing sulphuretted hydrogen through acid solutions of soluble cadmium salts, when it is precipitated as a pale yellow amorphous solid.
It is used as a pigment (cadmium yellow), for it retains its colour in an atmosphere containing sulphuretted hydrogen; it melts at a white heat, and on cooling solidifies to a lemon-yellow micaceous mass.
Normal cadmium carbonates are unknown, a white precipitate of variable composition being obtained on the addition of solutions of the alkaline carbonates to soluble cadmium salts.
Cadmium nitrate, Cd(N03)2.4H20, is a deliquescent salt, which may be obtained by dissolving either the metal, or its oxide or carbonate in dilute nitric acid.
Cadmium salts can be recognized by the brown incrustation which is formed when they are heated on charcoal in the oxidizing flame of the blowpipe; and also by the yellow precipitate formed when sulphuretted hydrogen is passed though their acidified solutions.
The mean value 112.467 was obtained by Baxter, Hines and Frevert (ibid., 1906, 28, p. 770) by analysing cadmium bromide.
Stromeyer detected a new metallic element, cadmium, in certain zinc ores; it was rediscovered at subsequent dates by other observers and its chemical resemblance to zinc noticed.
If the substance does not melt but changes colour, we may have present: zinc oxide - from white to yellow, becoming white on cooling; stannic oxide - white to yellowish brown, dirty white on cooling; lead oxide - from white or yellowish-red to brownish-red, yellow on cooling; bismuth oxide - from white or pale yellow to orange-yellow or reddish-brown, pale yellow on cooling; manganese oxide - from white or yellowish white to dark brown, remaining dark brown on cooling (if it changes on cooling to a bright reddishbrown, it indicates cadmium oxide); copper oxide - from bright blue or green to black; ferrous oxide - from greyish-white to black; ferric oxide - from brownish-red to black, brownish-red on cooling; potassium chromate - yellow to dark orange, fusing at a red heat.
If the hot bead is colourless and remains clear on cooling, we may suspect the presence of antimony, aluminium, zinc, cadmium, lead, calcium and magnesium.
The oxide films of antimony, arsenic, tin and bismuth are white, that of bismuth slightly yellowish; lead yields a very pale yellow film, and cadmium a brown one; mercury yields no oxide film.
The solution is filtered and treated with an excess of sulphuretted hydrogen, either in solution or by passing in the gas; this precipitates mercury (mercuric), any lead left over from the first group, copper, bismuth, cadmium, arsenic, antimony and tin as sulphides.
The precipitate formed by sulphuretted hydrogen may contain the black mercuric, lead, and copper sulphides, dark-brown bismuth sulphide, yellow cadmium and arsenious sulphides, orange-red antimony sulphide, brown stannous sulphide, dull-yellow stannic sulphide, and whitish sulphur, the last resulting from the oxidation of sulphuretted hydrogen by ferric salts, chromates, &c. Warming with ammonium sulphide dissolves out the arsenic, antimony and tin salts, which are reprecipitated by the addition of hydrochloric acid to the ammonium sulphide solution.
Filter from the bismuth hydrate, and if copper is present, add potassium cyanide till the colour is destroyed, then pass sulphuretted hydrogen, and cadmium is precipitated as the yellow sulphide.
If some of the anions, instead of being simple iodine ions represented chemically by the symbol I, are complex structures formed by the union of iodine with unaltered cadmium iodide - structures represented by some such chemical formula as I(CdI 2), the concentration of the solution round the anode would be increased by the passage of an electric current, and the phenomena observed would be explained.
The concentration of the simple copper ions is then so much diminished that the copper plate becomes an anode with regard to zinc. Thus the cell - copper I potassium cyanide solution I potassium sulphate solution - zinc sulphate solution I zinc - gives a current which carries copper into solution and deposits zinc. In a similar way silver could be made to act as anode with respect to cadmium.
An alloy of 15 parts of bismuth, 8 of lead, 4 of tin and 3 of cadmium (Wood's alloy) melts below 70° C.
Gold, silver, copper, lead, aluminium, cadmium, iron (pure), nickel and cobalt are practically amorphous, the crystals (where they exist) being so closely packed as to produce a virtually homogeneous mass.
Of the rest, the following are readily oxidized by steam at a red heat, with formation of hydrogen gas - zinc, iron, cadmium, cobalt, nickel, tin.
The same holds for the following group (A): [manganese, zinc, magnesium] iron, aluminium, cobalt, nickel, cadmium.
Iron, zinc, cadmium, also tin under certain conditions, reduce the dilute acid, partially at least, to nitrous oxide, N 2 0, or ammonium nitrate, NH4N03.
Potassium, for example, yields peroxide, K202 or K204; sodium gives Na202; the barium-group metals, as well as magnesium, cadmium, zinc, lead, copper, are converted into their monoxides MeO.
Second in importance is the carbonate, calamine (q.v.) or zinc spar, which at one time was the principal ore; it almost invariably contains the carbonates of cadmium, iron, manganese, magnesium and calcium, and may be contaminated with clay, oxides of iron, galena and calcite; "white calamine" owes its colour to much clay; "red calamine" to admixed iron and manganese oxides.
It is chemically related to cadmium and mercury, the resemblance to cadmium being especially well marked; one distinction is that zinc is less basigenic. Zinc is capable of isomorphously replacing many of the bivalent metals - magnesium, manganese, iron, nickel, cobalt and cadmium.
For the metallurgy see Walter Renton Ingalls, The Metallurgy of Zinc and Cadmium; Production and Properties of Zinc; A.
At a red heat rutile is produced, at the boiling point of zinc brookite, and of cadmium anatase.
For example, if vapours of the volatile metals cadmium, zinc and magnesium are allowed to act on platinum or palladium, alloys are produced.
Spring has shown that by compressing a finely divided mixture of i 5 parts of bismuth, 8 parts of lead, 4 parts of tin and 3 parts of cadmium, an alloy is pro duced which melts at ioo C., that is, much below the meltingpoint of any of the four metals.
The presence of minute quantities of cadmium, lead, bismuth, antimony, arsenic, tin, tellurium and zinc renders gold brittle, 2 ' 0 15th part of one of the three metals first named being sufficient to produce that quality.
The metal can be reduced by magnesium, zinc, cadmium, iron, tin, copper and substances like hypophosphorous acid from acid solutions or from alkaline ones by formaldehyde.
Tin amalgam is used for "silvering" mirrors, gold and silver amalgam in gilding and silvering, cadmium and copper amalgam in dentistry, and an amalgam of zinc and tin for the rubbers of electrical machines; the zinc plates of electric batteries are amalgamated in order to reduce polarization.
Troost made it available for specially high temperatures by employing porcelain vessels, sealing them with the oxyhydrogen blow-pipe, and maintaining a constant temperature by a vapour bath of mercury (3500), sulphur (4400), cadmium (860°) and zinc (1040°).
The alloy used is composed of 15 parts of bismuth, 8 of lead, 4 of tin and 3 of cadmium; it melts at 70°, and can be experimented with as readily as mercury.
Klein's solution, an aqueous solution of cadmium borotungstate, 2Cd(OH)2-B203.9W03.16H20, introduced by D.
Mourlot has shown that aluminium sulphide, zinc sulphide and cadmium sulphide are the only sulphur compounds which can resist the heat of the electric furnace without decomposition or volatilization, and of these aluminium sulphide is the only one which is decomposed by water with the evolution of sulphuretted hydrogen.
The anhydrous chlorides of nickel, cobalt, cadmium, barium, iron and lead act in the same way as catalysts at about 300° C., and the bromides of lead, cadmium, nickel and barium at about 320° C.
Other voltaic standards of electromotive force are in use, such as the Weston cadmium cell, the Helmholtz calomel cell, and the standard Daniell cell.
In the Weston standard cell cadmium and cadmium sulphate are substituted for zinc and zinc sulphate; it has the advantage of a much smaller coefficient of temperature variation than the Clark cell.
To prepare the cadmium amalgam, one part of pure cadmium is dissolved in six parts of pure mercury, and the product while warm and fluid is placed in one limb of the cell and warmed, to ensure perfect contact with the platinum wire.
The cadmium sulphate solution is prepared by digesting a saturated solution of cadmium sulphate with cadmium hydroxide to remove free acid, care being taken not to raise the temperature above 70° C., and then by digesting it still further with mercurous sulphate until no more precipitation occurs.
The cadmium sulphate solution must be saturated and have free crystals of the salt in it.
In making the paste, so much cadmium sulphate must be added that a saturated solution of that salt is formed and is present in the cell.
The cell has the electromotive force above stated if the amalgam of cadmium has from 6 to 13 parts of mercury to I of cadmium.
That is to say, the metre might be redetermined or restored as to its length within one ten-millionth part, by reference to, e.g., 1553163.5 wave-lengths of the red ray of the spectrum of cadmium, in air at 15° C. and 760 mm.
Perot and C. Fabry, employing their interferometer methods, have compared the wave-length of the red cadmium line with the standard metre in Paris and found it to be equal to 6438.4696 A, the observations being taken in dry air at 18° C and at a pressure of 76 cms. (g = 980.665).
The spectra of magnesium, calcium, zinc, cadmium and mercury, give the two branch series, and each series is repeated three times with constant difference of frequency.
The cadmium line having a wave-length of 2288 A broadens by pressure equally in both directions, but if mercury be added the broadening is more marked on the less refrangible side.
The remaining mineral products include lead, from which a considerable quantity of silver is extracted, copper, cobalt, arsenic, the rarer metal cadmium, alum, brown coal, marble, and a few of the commoner precious stones, jaspers, agates and amethysts.
The mines are still worked at the present day by French and Greek companies, but mainly for lead, manganese and cadmium.
Many hydrated forms of the sulphate are known, as are also double salts of the sulphate with potassium, sodium, ammonium, thallium and cadmium sulphates.
These melt between 91° and 95° C. The addition of cadmium gives still greater fusibility; in Wood's metal, for instance, which is Darcet's metal with half the tin replaced by cadmium, the melting point is lowered to 66°-71° C.; while another described by Lipowitz and containing 15 parts of bismuth, 8 of lead, 4 of tin and 3 of cadmium, softens at about 55° and is completely liquid a little above 60°.
Water, the carbonates and sulphates, and probably phosphates, and the metals platinum, gold, silver, cadmium, tin and copper have a specific cohesion double that of mercury.
The filtrate diluted to 200 cc. is carefully neutralized with hydrochloric acid, and excess of 6 cc. of the strong acid is added, and the solution saturated with hydrogen sulphide, which precipitates the copper and cadmium, metals which would otherwise interfere.
When cadmium is not present the copper may be precipitated by boiling the acidulated ammoniacal solution with test lead and titrating, as before described, without removing the lead and copper from the solution.
Silver, arsenic and cadmium, if present, are precipitated with the copper and affect the accuracy of the results; they should be removed by special methods.
zinc, tin and cadmium) with precipitation of arsenic and formation of arseniuretted hydrogen.
4 for cadmium in which both the specific heat and the Peltier effect are positive, and also for platinum and nickel in which both coefficients are negative.
Concentrations of lead, zinc, cadmium and other heavy metals in lichens and marine bivalves are measured.
I had a range of colors -- Prussian blue, burnt umber, cadmium yellow -- but no ' Malawi glow ' .
A small proportion of PV contains cadmium, the oxides of which are toxic in very small doses.
cadmium used is very small so the cell is not as unfriendly to the environment as We believe.
cadmium plated with conventional methods.
The task could be broadened to cover other heavy metals including cadmium & barium.
Over a period of 14 months we found cadmium in counterfeits to average more than five times the concentrations in genuine brands.
cadmium in foods.
cadmium in one mobile phone battery can contaminate 600,000 liters of water.
In the first instance the study will be confined to the heavy metals cadmium, lead, arsenic and zinc.
This also helps to reduce the amount of hazardous metals e.g. cadmium, nickel and mercury, in the waste stream.
Analysis lead, cadmium, copper and zinc concentrations were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS ).
In portable electronics, they avoid toxic cadmium and mercury battery waste.
The battery was made by NIFE Batteries Ltd and was a nickel cadmium alkaline battery designed on the standard two-part principle.
cadmium telluride wafers will do for x-ray signals.
Cadmium ion plating: The deposition of cadmium ion plating: The deposition of cadmium by a vacuum process to provide galvanic corrosion protection.
cadmium sulfide light sensitive resistor gives the buggy its ' eye ' .
cadmium zinc telluride CZT which is being manufactured at Durham University.
cadmium batteries market would be exempt.
cadmium concentrations were generally higher than would be found in most foods.
In practice 70% of the portable nickel cadmium batteries market would be exempt.
Exposure to the metal cadmium may be a risk.
On heavy metals: lead, mercury, cadmium and hexavalent chromium will be banned from vehicle components by 1 January 2003.
Hydrogen is stored in rechargeable nickel-metal hydride (Ni-MH) batteries, which have a higher energy capacity than environmentally toxic cadmium batteries.
The free oxygen then oxidizes the cadmium metal to form more cadmium hydroxide to prevent hydrogen from being formed.
They use nickel and cadmium as electrodes and aqueous potassium hydroxide as electrolyte.
Cadmium coatings also have good lubricity, easy solderability and other properties, which are essential for reliable service life in many engineering components.
milkshake mixers contained very low concentrations of cadmium.
nickel cadmium batteries market would be exempt.
cadmium ion plating: The deposition of cadmium by a vacuum process to provide galvanic corrosion protection.
Most inexpensive photosensors use cadmium sulfide as the active element for light detection.
Electronic photosensors are more costly than cadmium sulfide cells but savings in energy costs generally justify their installation.
He explained: " What silicon has done for digital cameras, cadmium telluride wafers will do for x-ray signals.
The material you would be using is cadmium zinc telluride CZT which is being manufactured at Durham University.
The research work centers on the development of LEDs and photodiodes using narrow band-gap semiconductors, in particular indium antimonide and cadmium mercury telluride.
Semiconductor detectors; types of semiconductor (silicon, germanium, cadmium telluride cadmium zinc telluride etc.
In many respects it resembles chlorine in its chemical behaviour, a circumstance noted by Gay-Lussac; it combines directly with hydrogen (at 50oÃ‚° to 550Ã‚° C.) to form hydrocyanic acid, and with chlorine, bromine, iodine and sulphur, to form cyanogen chloride, &c.; it also combines directly with zinc, cadmium and iron to form cyanides of these metals.
Cadmium oxide, CdO, is a brown powder of specific gravity 6.5, which can be prepared by heating the metal in air or in oxygen; or by ignition of the nitrate or carbonate; by heating the metal to a white heat in a current of oxygen it is obtained as a dark red crystalline sublimate.
Cadmium chloride and iodide have been shown to behave in an anomalous way in aqueous solution (W.
Cadmium is estimated quantitatively by conversion into the oxide, being precipitated from boiling solutions by the addition of sodium carbonate, the carbonate thus formed passing into the oxide on ignition.
Journ., 1892, 14, p. 261) by conversion of cadmium into the oxalate and then into oxide, obtained values ranging from 111.981 to 112.05, whilst W.
Chem., 1891, I, p. 364), by the electrolytic reduction of cadmium oxide in potassium cyanide solution, obtained as a mean value 112.055.
If the incrustation be white and readily volatile, arsenic is present, if more difficultly volatile and beads are present, antimony; zinc gives an incrustation yellow whilst hot, white on cooling, and volatilized with difficulty; tin gives a pale yellow incrustation, which becomes white on cooling, and does not volatilize in either the reducing or oxidizing flames; lead gives a lemon-yellow incrustation turning sulphur-yellow on cooling, together with metallic malleable beads; bismuth gives metallic globules and a dark orange-yellow incrustation, which becomes lemon-yellow on cooling; cadmium gives a reddish-brown incrustation, which is removed without leaving a gleam by heating in the reducing flame; silver gives white metallic globules and a dark-red incrustation.
An alloy of 15 parts of bismuth, 8 of lead, 4 of tin and 3 of cadmium (Wood's alloy) melts below 70Ã‚° C.
The chief ore is zinc blende, or sphalerite (see Blende), which generally contains, in addition to zinc sulphide, small amounts of the sulphides of iron, silver and cadmium.
Troost made it available for specially high temperatures by employing porcelain vessels, sealing them with the oxyhydrogen blow-pipe, and maintaining a constant temperature by a vapour bath of mercury (3500), sulphur (4400), cadmium (860Ã‚°) and zinc (1040Ã‚°).
The alloy used is composed of 15 parts of bismuth, 8 of lead, 4 of tin and 3 of cadmium; it melts at 70Ã‚°, and can be experimented with as readily as mercury.
The anhydrous chlorides of nickel, cobalt, cadmium, barium, iron and lead act in the same way as catalysts at about 300Ã‚° C., and the bromides of lead, cadmium, nickel and barium at about 320Ã‚° C.
It is most conveniently made up in a glass vessel of H form, pure mercury and cadmium amalgam being the two elements (fig.
The cadmium sulphate solution is prepared by digesting a saturated solution of cadmium sulphate with cadmium hydroxide to remove free acid, care being taken not to raise the temperature above 70Ã‚° C., and then by digesting it still further with mercurous sulphate until no more precipitation occurs.
That is to say, the metre might be redetermined or restored as to its length within one ten-millionth part, by reference to, e.g., 1553163.5 wave-lengths of the red ray of the spectrum of cadmium, in air at 15Ã‚° C. and 760 mm.
Perot and C. Fabry, employing their interferometer methods, have compared the wave-length of the red cadmium line with the standard metre in Paris and found it to be equal to 6438.4696 A, the observations being taken in dry air at 18Ã‚° C and at a pressure of 76 cms. (g = 980.665).
These melt between 91Ã‚° and 95Ã‚° C. The addition of cadmium gives still greater fusibility; in Wood's metal, for instance, which is Darcet's metal with half the tin replaced by cadmium, the melting point is lowered to 66Ã‚°-71Ã‚° C.; while another described by Lipowitz and containing 15 parts of bismuth, 8 of lead, 4 of tin and 3 of cadmium, softens at about 55Ã‚° and is completely liquid a little above 60Ã‚°.
Other metals may be rendered passive; for example, zinc does not precipitate copper from solutions of the double cyanides and sulphocyanides, nickel and cadmium from the nitrates, and iron from the sulphate, but it immediately throws down nickel and cadmium from the sulphates and chlorides, and lead and copper from the nitrates (see 0.
It covers radiation detection, cadmium zinc telluride detectors and X-ray fluorescence.
Nickel Cadmium (NiCd) Batteries - While these batteries are older technology, they are also the battery most people are familiar with.
Nickel Metal Hydrid (NiMH) Batteries - Manufacturers of these batteries state that they are better for the environment than the NiCd batteries because they don't contain cadmium.
Some states ban phone owners from disposing of their nickel cadmium phone batteries in the trash.
There are some materials used in the manufacture of computers and electronic equipment, such as lead, nickel, cadmium and mercury, that need to be disposed of in a special manner in order not to harm the environment.
Cell phone circuit boards, batteries and other components contain dangerous chemicals, such as mercury, lead, cadmium, and polyvinyl chloride (PVC).
Electronics contain hazardous materials such as lead, mercury and cadmium.
The heavy metals most often implicated in human poisoning are lead, mercury, arsenic, and cadmium.
Cadmium toxicity is generally indicated when urine levels exceed 10 mg/dL of creatinine and blood levels exceed 5 mg/dL.
Chelation therapy is effective in treating lead, mercury, and arsenic poisoning, but it is not useful in treating cadmium poisoning.
As of 2004, no treatment had been proven effective for cadmium poisoning.
"Urinary cadmium levels in the U.S. working population, 1988-1994."
Allergic responses to tattoos may occur due to the pigment compounds used, such as oxides of iron, mercury, chromium, cadmium, and cobalt and synthetic organic dyes.
Cadmium missiles don't do anything, but a new weapon, the freezing laser gun, stops Godzilla in his tracks, but only for six hours.
Fromm have shown that alloys may be precipitated from dilute solutions by zinc, cadmium, tin, lead and copper.
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