Sulphur arsenic and

In saline sediments aliphatic and polyaromatic hydrocarbons carbohydrates haloaromatic compounds chlorophenols basic nitrogen compounds various organosulphur compounds mixtures of organic compounds total sulphur arsenic and organic compounds of lead, mercury and tin. ... 

Geber takes for granted that the supreme aim of the science is the removing of imperfections of metals so that they shall become perfect. He accepts the existence of the philosopher s stone and of the elixirs, red and white, that in these elixirs red and white there is no other thing than quicksilver and sulphur, and because all metallic bodies are compounded of quicksilver and sulphur—pure or impure—accidentally (superficially) and not in their first nature, therefore by convenient preparation it is possible to take away such impurity. The natural principles of the metals are three sulphur, arsenic and quicksilver. . . . Sulphur is a fatness of the earth thickened until it be hardened and made dry, and when it is hardened it is called sulphur. . . . Arsenic is a subtle matter like to sulphur therefore it need not be otherwise defined than sulphur. . . . Quicksilver is a viscous water united in the bowels of the earth with white subtle earth until the moist is tempered with the dry. Expressions such as these illustrate how completely the author is dependent upon the conventional chemical philosophy of the Arabian alchemists. 

The salts of the alkali and alkaline earth metals, as well as of gold, magnesium, beryllium and yttrium, are soluble in water, the solutions being colourless or pale yellow. They gradually decompose, however, when kept, with deposition of sulphur, arsenic and arsenic pentasulphide. The following thioarsenates have been described. 

The mechanically dressed ore is first roasted in order to remove sulphur, arsenic, and other volatile ingredients, and then heated in a reverberatory furnace with sodium carbonate or sodium sulphate. The product is extracted with %varm dilute sulphuric acid, whereupon the uranium passes into solution, whilst the radium remains in the residue witlr calcium, barium, and lead. Tliis residue, which is the starting material for tlie extraction of radium, also contains silica and small quantities of copper, bismutli, arsenic, antimony, iron, aluminium, manganese, zinc, nickel, cobalt, thallium, vanadium, columbium, tantalum, and rare earths. 

Siemens (1705) of Goslar advised metallurgists to protect themselves from the vapours of mercury, antimony, sulphur, arsenic, and lead by avoiding their inhalation and by the swallowing of sahva. It is best to work in the open air. Protective drugs include ginger, cardamom, and cinnamon. For beverages Siemens mentioned decocts of veronica, mallow and ivy, and coffee with plenty of warm cow milk. 

Before this treatment, the cassiterite content of the ore is increased by removing impurities such as clay, by washing and by roasting which drives off oxides of arsenic and sulphur. The crude tin obtained is often contaminated with iron and other metals. It is, therefore, remelted on an inclined hearth the easily fusible tin melts away, leaving behind the less fusible impurities. The molten tin is finally stirred to bring it into intimate contact with air. Any remaining metal impurities are thereby oxidised to form a scum tin dross ) on the surface and this can be skimmed off Very pure tin can be obtained by zone refining. 

Crude lead contains traces of a number of metals. The desilvering of lead is considered later under silver (Chapter 14). Other metallic impurities are removed by remelting under controlled conditions when arsenic and antimony form a scum of lead(II) arsenate and antimonate on the surface while copper forms an infusible alloy which also takes up any sulphur, and also appears on the surface. The removal of bismuth, a valuable by-product, from lead is accomplished by making the crude lead the anode in an electrolytic bath consisting of a solution of lead in fluorosilicic acid. Gelatin is added so that a smooth coherent deposit of lead is obtained on the pure lead cathode when the current is passed. The impurities here (i.e. all other metals) form a sludge in the electrolytic bath and are not deposited on the cathode. 

Cobalt compounds have been in use for centuries, notably as pigments ( cobalt blue ) in glass and porcelain (a double silicate of cobalt and potassium) the metal itself has been produced on an industrial scale only during the twentieth century. Cobalt is relatively uncommon but widely distributed it occurs biologically in vitamin B12 (a complex of cobalt(III) in which the cobalt is bonded octahedrally to nitrogen atoms and the carbon atom of a CN group). In its ores, it is usually in combination with sulphur or arsenic, and other metals, notably copper and silver, are often present. Extraction is carried out by a process essentially similar to that used for iron, but is complicate because of the need to remove arsenic and other metals. 

Optional experiment. When all the air has been displaced, collect a test-tube of the gas over water (by appropriate inclination of the end of the delivery tube beneath the mouth of a test-tube filled with water and supported in a beaker of water). Observe the colour and odour of the gas. Ignite the test-tube of gas, and note the luminosity of the flame and the amount of carbon deposited. Pure acetylene is almost odourless the characteristic odour observed is due to traces of hydrides of phosphorus, arsenic and sulphur. 

Antimony is a bluish white metal with good lustre but poor heat conducting ability. It is stable in air and resistant to dilute acids but attacked by halogens, sulphur, phosphorus and arsenic. 

That the sulphuric. acid act.s in the. ihove in.inner, md not merely as a dehydrating apciit appears not only fioin the form.ation of iniKccl ethers, but al.so fiom the f.ii t that the sulphuric acid m.ay be replaced by phiisphonc, arsenic and benzene sulphonic acids. 

Of the elements commonly found in lead alloys, zinc and bismuth aggravate corrosion in most circumstances, while additions of copper, tellurium, antimony, nickel, silver, tin, arsenic and calcium may reduce corrosion resistance only slightly, or even improve it depending on the service conditions. Alloying elements that are of increasing importance are calcium especially in maintenance-free battery alloys and selenium, or sulphur combined with copper as nucleants in low antimony battery alloys. Other elements of interest are indium in anodesaluminium in batteries and selenium in chemical lead as a grain refiner ". 

Method A Standardisation with arsenic (III) oxide. Discussion. The most trustworthy method for standardising cerium(IV) sulphate solutions is with pure arsenic(III) oxide. The reaction between cerium(IV) sulphate solution and arsenic(III) oxide is very slow at the ambient temperature it is necessary to add a trace of osmium tetroxide as catalyst. The arsenic(III) oxide is dissolved in sodium hydroxide solution, the solution acidified with dilute sulphuric acid, and after adding 2 drops of an osmic acid solution prepared by dissolving 0.1 g osmium tetroxide in 40mL of 0.05M sulphuric acid, and the indicator (1-2 drops ferroin or 0.5 mL /V-phenylanthranilic acid), it is titrated with the cerium(IV) sulphate solution to the first sharp colour change orange-red to very pale blue or yellowish-green to purple respectively. 

Procedure. Weigh out accurately about 0.2 g of arsenic(III) oxide, previously dried at 105-110 °C for 1-2 hours, and transfer to a 500 mL beaker or to a 500 mL conical flask. Add 20 mL of approx. 2M sodium hydroxide solution, and warm the mixture gently until the arsenic(III) oxide has completely dissolved. Cool to room temperature, and add 100 mL water, followed by 25 mL 2.5M sulphuric acid. Then add 3 drops 0.01 M osmium tetroxide solution (0.25 g osmium tetroxide (CARE FUME CUPBOARD) dissolved in 100 mL 0.05M sulphuric acid) and 0.5 mL AT-phenylanthranilic acid indicator (or 1-2 drops of ferroin). Titrate with the 0.1 M cerium(IV) sulphate solution until the first sharp colour change occurs (see Discussion above). Repeat with two other samples of approximately equal weight of arsenic(III) oxide. 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

Many heavy metals react with dithiol to give coloured precipitates, e.g. bismuth, iron(III), copper, nickel, cobalt, silver, mercury, lead, cadmium, arsenic, etc. molybdate and tungstate also react. Of the various interfering elements, only arsenic distils over with the tin when a mixture is distilled from a medium of concentrated sulphuric acid and concentrated hydrobromic acid in a current of carbon dioxide. If arsenic is present in quantities larger than that of the tin it should be removed. 

This technique has been applied to the determination of arsenic, selenium, organocompounds of arsenic, mercury and tin in soils, carbohydrates, total sulphur, arsenic, antimony, bismuth, selenium and organocompounds of mercury, tin and silicon in non-saline sediments, arsenic, bismuth, selenium or organotin compounds in saline sediments and arsenic and selenium in sludges. 

The acid digestion procedure described above for biological tissues. Crock and Lichte [135] recently described a similar procedure, involving hydrofluoric as well as nitric, perchloric and sulphuric acids, for dissolution of geological materials prior to arsenic and antimony determination by atomic absorption spectrometry. 

Later on, there was added a third principle Salt or Arsenic, but without its having added anything essential to either Sulphur or Mercury. Salt simply represents the means to achieve a Union between Sulphur and Mercury [le sel c etait simplement un moyen d union entre le soufre et le mercure] it works like a vital spirit mediating between Body and Soul.. . . Sulphur, Mercury and Salt are, in any event, only abstractions [ne sont done que des abstractions], conveniently employed in order to designate a certain group of intrinsic properties. ... 

From what has just been said with regard to carbon, it is evident that the atomicity of an element is, apparently at least, not a fixed and invariable quantity thus nitrogen is sometimes equivalent to five atoms of hydrogen, as in ammonic chloride, (i H Cl), sometimes to three atoms, as in ammonia (N" H,), mid sometimes to only one atom, as in nitrous oxide (N,0). But it is found that this variation in atomicity always takes place by the disappearance or development of an even number of bonds thus nitrogen is either a pentad, a triad, or a monad phosphorus and arsenic, either pentads or triads carbon and tin, either tetrads or dyads and sulphur, selenium, and tellurium, either hexads, tetrads, or dyads. 

Preparation.—1. In the pure state by the action of sulphuric acid on an alloy of arsenic and sine —... 

According to C. F. Barwald and A. Monheim (1835), the decomposition is accelerated by the presence of organic substances. J. Milbauer tried the effect of thirty-two metal chlorides of sodium tungstate and molybdate of uranyl sulphate and of sulphuric, selenic, arsenic, and boric acids on the photo-decomposition of chlorine water, and found. that none accelerated but that most retarded the action. Chlorine catalyzes the decomposition of bromine water and bromine, chlorine water while iodine does not accelerate, but rather retards the reaction, probably by forming relatively stable iodine compounds. A. Bcnrath and H. Tuchel found the temp, coeff. of the velocity of the reaction with chlorine water between 5° and 30° increases in the ratio 1 1 395 per 10°. 

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