Prolonged ingestion of arsenic may cause pigmentary changes in the skin.
The molybdates are also capable of combining with other oxides (such as phosphorus and arsenic pentoxides) yielding very complex salts.
If we thought Howie was upset over the Youngblood matter, it was arsenic versus ice cream compared to how enraged he was over a challenge to his ability.
Sulphur, arsenic, asphalt and petroleum exist.
This precipitate is insoluble in cold dilute acids, in ammonium sulphide, and in solutions of the caustic alkalis," a behaviour which distinguishes it from the yellow sulphides of arsenic and tin.
There is some evidence that arsenic has a prophylactic effect.
Mining is carried on only to a small extent for arsenic, although there are traces of former more extensive workings for other metals.
They are readily withdrawn from the surface of the lead, and are worked up into antimony (arsenic) - tin-lead and antimony-lead alloys.
To extract the metal, the pitchblende is first roasted in order to remove the arsenic and sulphur.
His first original paper (1799) was on the compounds of arsenic and antimony with oxygen and sulphur, and of his other separate investigations one of the most important was that on the compound ethers, begun in 1807.
Many substances were employed in ancient medicine: galena was the basis of a valuable Egyptian cosmetic and drug; the arsenic sulphides, realgar and orpiment, litharge, alum, saltpetre, iron rust were also used.
Sulphur containing selenium, such as occurs in the isle of Vulcano in the Lipari Isles, may be orange-red; and a similar colour is seen in sulphur which contains arsenic sulphide, such as that from La Solfatara near Naples.
One group was treated with arsenic, and of these 36 escaped altogether, while three had mild attacks; the remaining 39.
The irritant may be chemical, as is seen in the skin cancers that develop in workers in paraffin, petroleum, arsenic and aniline.
Such pyrites sulphur is usually contaminated with arsenic, and conse- quently is of less value than Sicilian sulphur, which is characteristically free from this impurity.
Glauber showed how to prepare hydrochloric acid, spiritus salis, by heating rock-salt with sulphuric acid, the method in common use to-day; and also nitric acid from saltpetre and arsenic trioxide.
The allotropy of arsenic and antimony is also worthy of notice, but in the case of the first element the variation is essentially non-metallic, closely resembling that of phosphorus.
Taking as types hydrogen, hydrochloric acid, water and ammonia, he postulated that all organic compounds were referable to these four forms: the hydrogen type included hydrocarbons, aldehydes and ketones; the hydrochloric acid type, the chlorides, bromides and iodides; the water type, the alcohols, ethers, monobasic acids, acid anhydrides, and the analogous sulphur compounds; and the ammonia type, the amines, acid-amides, and the analogous phosphorus and arsenic compounds.
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.
In acid copper solutions, mercury is deposited before the copper with which it subsequently amalgamates; silver is thrown down simultaneously; bismuth appears towards the end; and after all the copper has been precipitated, arsenic and antimony may be deposited.
Of the impurities, most of the copper, nickel and copper, considerable arsenic, some antimony and small amounts of silver are removed by liquation.
To remove tin, arsenic and antimony, the lead has to be brought up to a bright-red heat, when the air has a strongly oxidizing effect.
Tin is removed mainly as a powdery mixture of stannate of lead and lead oxide, arsenic and antimony as a slagged mixture of arsenate and antimonate of lead and lead oxide.
The temperature is then raised, and the scum which forms on the surface is withdrawn until pure litharge forms, which only takes place after all the tin, arsenic and antimony have been eliminated.
Arsenic renders lead harder.
An alloy made by addition of about 6th of arsenic has been used for making shot.
Pliny mentions it under the name of minium, but it was confused with cinnabar and the red arsenic sulphide; Dioscorides mentions its preparation from white lead or lead carbonate.
The metals used in different combinations included tin, aluminium, arsenic, antimony, bismuth and boron; each of these, when united in certain proportions with manganese, together with a larger quantity of copper (which appears to serve merely as a menstruum), constituted a magnetizable alloy.
Among the minerals are silver, platinum, copper, iron, lead, manganese, chromium, quicksilver, bismuth, arsenic and antimony, of which only iron and manganese have been regularly mined.
Its chief mineral products are coal, nitre, sulphur, alum, soda, saltpetre, gypsum, porcelain-earth, pipe-clay, asphalt, petroleum, marble and ores of gold, silver, mercury, copper, iron, lead, zinc, antimony, cobalt and arsenic. The principal mining regions are Zsepes-Giimor in Upper Hungary, the Kremnitz-Schemnitz district, the Nagybanya district, the Transylvanian deposits and the Banat.
From the solution the arsenic, copper, &c., are precipitated by sulphuretted hydrogen as sulphides, which are filtered off.
The chief method employed for their destruction is spraying the swarms with arsenic. The districts with the greatest area under cultivation are Heidelberg, Witwatersrand, Pretoria, Standerton and Krugersdorp. The chief crops grown for grain are wheat, maize (mealie) and kaffir corn, but the harvest is inadequate to meet local demands.
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.
In the effects of simpler poisons the recognition of unity in diversity, as in the affiliation of a peripheral neuritis to arsenic, illustrated more definitely this serial or etiological method of classifying diseases.
Semi-opacity and opacity are usually produced by the addition to the glass-mixtures of materials which will remain in suspension in the glass, such as oxide of tin, oxide of arsenic, phosphate of lime, cryolite or a mixture of felspar and fluorspar.
Oxidation may be effected by the addition to the glass mixture of a substance which gives up oxygen at a high temperature, such as manganese dioxide or arsenic trioxide.
A certain proportion of soda ash (carbonate of soda) is also used in some works in sheet-glass mixtures, while " decolorizers " (substances intended to remove or reduce the colour of the glass) are also sometimes added, those most generally used being manganese dioxide and arsenic. Another essential ingredient of all glass mixtures containing sulphate of soda is some form of carbon, which is added either as coke, charcoal or anthracite coal; the carbon so introduced aids the reducing substances contained in the atmosphere of the furnace in bringing about the reduction of the sulphate of soda to a condition in which it combines more readily with the silicic acid of the sand.
But the presence of moderate proportions of cuprous oxide has been found to correct the evil influence of small contaminations by arsenic, antimony, lead and other foreign metals.
Arsenic combines readily with all metals into true arsenides, which latter, in general, are soluble in the metal itself.
Tin and antimony (also arsenic) are converted by it (ultimately) into hydrates of their highest oxides Sn0 2, Sb205 (As 2 O 5) - the oxides of tin and antimony being insoluble in water and in the acid itself.
Of the several individual chlorides, the following are liquids or solids, volatile enough to be distilled from glass vessels: AsC13, SbC1 3, SnCl 4, BiCl 3, HgC1 2, the chlorides of arsenic, antimony, tin, bismuth, mercury respectively.
When the vapours readily condense to a solid form the condensing plant may take the form of large chambers; such conditions prevail in the manufacture of arsenic, sulphur and lampblack: in the latter case (which, however, is not properly one of distillation) the chamber is hung with sheets on which the pigment collects.
There are also present small quantities of arsenic and antimony, and zinc is found generally as a mere trace, but sometimes reaching to 6%.
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.
Native arsenic and antimony are also very frequently found to contain gold and silver.
It appears that amalgamation is often impeded by the tarnish found on the surface of the gold when it is associated with sulphur, arsenic, bismuth, antimony or tellurium.
The gold is precipitated as the sulphide, together with any arsenic, antimony, copper, silver and lead which may be present.
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.
In addition to the separation of the silver the operation extends to the elimination of the last traces of lead, tin, arsenic, &c. which have resisted the preceding cupeilation.
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.
The slight variations in specific gravity are due to the presence of small amounts of arsenic, sulphur or tellurium, or to enclosed impurities.
The former is found, generally mixed with iron, copper and arsenic oxides, in Bohemia, Siberia, Cornwall, France (Meymac) and other localities; it also occurs admixed with bismuth carbonate and hydrate.
The crude metal obtained by the preceding processes is generally contaminated by arsenic, sulphur, iron, nickel, cobalt and antimony, and sometimes with silver or gold.
The basic nitrate is the salt generally prepared, and, in general outline, the process consists in dissolving the metal in nitric acid, adding water to the solution, boiling the precipitated basic nitrate with an alkali to remove the arsenic and lead, dissolving the residue in nitric acid, and reprecipitating as basic nitrate with water.
It is precipitated as the metal from solutions of its salts by the metals of the alkalis and alkaline earths, zinc, iron, copper, &c. In its chemical affinities it resembles arsenic and antimony; an important distinction is that it forms no hydrogen compound analogous to arsine and stibine.
MISPICKEL, a mineral consisting of iron sulpharsenide, FeAsS; it contains 40% of arsenic, and is of importance as an ore of this element.
Arsenical varieties of marcasite, containing up to 5% of arsenic, are known as lonchidite and kyrosite.
Arsenic is found.
For sodii arsenas and cacodylate see Arsenic. Sapo durus (hard soap) is a compound of sodium with olive oil, and sago animalis (curd soap) is chiefly sodium stearate.
In 1775 he investigated arsenic acid and its reactions, discovering arseniuretted hydrogen and "Scheele's green" (copper arsenite), a process for preparing which on a large scale he published in 1778.
The mineral nearly always contains a small amount of silver, and sometimes antimony, arsenic, copper, gold, selenium, &c. Argentiferous galena is an important source of silver; this metal is present in amounts rarely exceeding %, and often less than o 03% (equivalent to 104 ounces per ton).
Iodine in the presence of water frequently acts as an oxidizing agent; thus arsenious acid and the arsenites, on the addition of iodine solution, are converted into arsenic acid and arsenates.
It is a most powerful oxidizing agent, phosphorus being readily oxidized to phosphoric acid, arsenic to arsenic acid, silicon at 250° C. to silica, and hydrochloric acid to chlorine and water.
Other minerals whose production may be found stated in detail in the annual volume on Mineral Resources of the United States Geological Survey are: natural pigments, felspar, white mica, graphite, fluorspar, arsenic, quartz, barytes, bromine.
When there is appreciable absorption as in the case of the vapours of chlorine, bromine, iodine, sulphur, selenium and arsenic, luminosity begins at a red heat.
The oxide and carbonate of magnesium are also invaluable as antidotes, since they form insoluble compounds with oxalic acid and salts of mercury, arsenic, and copper.
Further he prepared a large number of substances, including the chlorides and other salts of lead, tin, iron, zinc, copper, antimony and arsenic, and he even noted some of the phenomena of double decomposition.
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.
Besides a large number of animal and vegetable substances, many precipitates formed in the course of inorganic chemical reactions are non-crystalline and appear in the colloidal state, instances are the sulphides of antimony and arsenic and the hydroxides of iron and alumina.
The mining industry generally has declined, but there is a trade in arsenic, extracted from the copper ore.
Arsenic is an impurity which may be of serious consequence in some of the purposes to which pyrites is applied.
The presence of copper, nickel and arsenic is possibly due in many cases to traces of kindred minerals, like chalcopyrite, pentlandite and mispickel.
It is also important for this purpose that the ore should be as free as possible from arsenic (see Sulphuric Acid).
Arsenic, saltpetre, alum, naphtha and sulphur may be collected in the volcanic districts.
A problem to which he returned repeatedly was that of separating nickel and cobalt from their ores and freeing them from arsenic; and in the course of his long laboratory practice he worked out numerous processes for the preparation of pure chemicals and methods of exact analysis.
Of other minerals (with the exceptions of coal, iron and salt treated below) nickel and antimony are found in the upper Harz; cobalt in the hilly districts of Hesse and the Saxon Erzgebirge; arsenic in the Riesengebirge; quicksilver in the Sauerland and in the spurs of the Saarbrucken coal hills; graphite in Bavaria; porcelain clay in Saxony and Silesia; amber along the whole Baltic coast; and lime and gypsum in almost all parts.
Several metals have been mined also, including gold, copper, lead, iron and arsenic; but the amounts produced have not been great, and many of the mines are no longer working.
Associated with the silver minerals are rich ores of cobalt and nickel, combined with arsenic, antimony and sulphur, which would be considered valuable if occurring alone, but are not paid for under present conditions, since they are difficult to separate and refine.
In the same neighbourhood are found cobalt, arsenic and bismuth.
Silver, copper, lead and iron are worked to some profit, while arsenic, alum, graphite, marble, porcelain, precious and building stones are also found.
The metals, which by combination with oxygen became oxides, were antimony, silver, arsenic, bismuth, cobalt, copper, tin, iron, manganese, mercury, molybdenum, nickel, gold, platinum, lead, tungsten and zinc; and the "simple earthy salifiable substances" were lime, baryta, magnesia, alumina and silica.
Many different alloys have been suggested, some including silver, nickel, zinc or arsenic; but that which has practically been found best is an alloy of four equivalents of copper to one of tin, or the following proportions by weight: copper 252, tin 117.8.
It occurs in the uncombined condition and alloyed with iron in meteorites; as sulphide in millerite and nickel blende, as arsenide in niccolite and cloanthite, and frequently in combination with arsenic and antimony in the form of complex sulphides.
The most considerable towns of the interior were Gangra, in ancient times the capital of the Paphlagonian kings, afterwards called Germanicopolis, situated near the frontier of Galatia, and Pompeiopolis, in the valley of the Amnias (a tributary of the Halys), near which were extensive mines of the mineral called by Strabo sandarake (red arsenic), which was largely exported from Sinope.
Tungstic acid closely resembles molybdic acid in combining with phosphoric, arsenious, arsenic, boric, vanadic and silicic acids to form highly complex acids of which a great many salts exist.
At ordinary temperatures it unites directly with many other elements; thus with hydrogen, combination takes place in direct sunlight with explosive violence; arsenic, antimony, thin copper foil and phosphorus take fire in an atmosphere of chlorine, forming the corresponding chlorides.
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.
Minerals produced in small quantities include gypsum, millstones, salt and sandstone, and among those found but not produced (in 1902) in commercial quantities may be mentioned allanite, alum, arsenic, bismuth, carbonite, felspar, kaolin, marble, plumbago, quartz, serpentine and tin.
Arsenic formed the subject of his first recorded investigation, on which he was engaged at least as early as 1764, and in 1766 he began those communications to the Royal Society on the chemistry of gases, which are among his chief titles to fame.
Tetrahedrite, fahlerz, or grey copper, contains from 30 to 48% of copper, with arsenic, antimony, iron and sometimes zinc, silver or mercury.
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 roasted ore is then smelted to a mixture of copper and iron sulphides, known as copper " matte " or " coarse-metal," which contains little or no arsenic, antimony or silica.
The impurities contained in coarse-copper are mainly iron, lead, zinc, cobalt, nickel, bismuth, arsenic, antimony, sulphur, selenium and tellurium.
The roasting should be conducted so as to eliminate as much of the arsenic and antimony as possible, and to leave just enough sulphur as is necessary to combine with all the copper present when the calcined ore is smelted.
A similar operation is conducted when arsenic is present; basic-lined reverberatory furnaces have been used for the same purpose.
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.
of cathode, and an electrolyte containing qlb of copper sulphate and z lb of sulphuric acid per gallon, all the gold, platinum and silver present in the crude copper anode remain as metals, undissolved, in the anode slime or mud, and all the lead remains there as sulphate, formed by the action of the sulphuric acid (or S04 ions); he found also that arsenic forms arsenious oxide, which dissolves until the solution is saturated, and then remains in the slime, from which on long standing it gradually dissolves, after conversion by secondary reactions into arsenic oxide; antimony forms a basic sulphate which in part dissolves; bismuth partly dissolves and partly remains, but the dissolved portion tends slowly to separate out as a basic salt which becomes added to the slime; cuprous oxide, sulphide and selenides remain in the slime, and very slowly pass into solution by simple chemical action; tin partly dissolves (but in part separates again as basic salt) and partly remains as basic sulphate and stannic oxide; zinc, iron, nickel and cobalt pass into solution - more readily indeed than does the copper.
Neutral solutions are to be avoided because in them silver dissolves from the anode and, being more electro-negative than copper, is deposited at the cathode, while antimony and arsenic are also deposited, imparting a dark colour to the copper.
Electrolytic copper should contain at least 99.92% of metallic copper, the balance consisting mainly of oxygen with not more than o oi% in all of lead, arsenic, antimony, bismuth and silver.
Copper combines directly with arsenic to form several arsenides, some of which occur in the mineral kingdom.
The figures for the more important minerals are as follows: Gold ore, manganese ore and uranium ore are produced in small quantities, and the list of minerals worked in the United Kingdom also includes chalk, lead, alum, phosphate of lime, chert and flint, gravel and sand, zinc ore, gypsum, arsenic, copper, barytes, wolfram and strontium sulphate.
ANTIMONY (symbol Sb, atomic weight 120.2), one of the metallic chemical elements, included in the same natural family of the elements as nitrogen, phosphorus, arsenic, and bismuth.
Distinct crystals are rarely met with; these are rhombohedral and isomorphous with arsenic and bismuth; they have a perfect cleavage parallel to the basal plane, c (111), and are sometimes twinned on a rhombohedral plane, e (1 ro).
Antimony, like phosphorus and arsenic, combines directly with hydrogen.
Chronic poisoning by antimony is very rare, but resembles in essentials chronic poisoning by arsenic. In its medico-legal aspects antimonial poisoning is of little and lessening importance.
Petroleum has been found near Torres Vedras; pitchblende, arsenic, anthracite and zinc are also mined.
He holds the doctrine that everything endowed with an apparent quality possesses an opposite occult quality in much the same terms as it is found in Latin writers of the middle ages, but he makes no allusion to the theory of the generation of the metals by sulphur and mercury, a theory generally attributed to Geber, who also added arsenic to the list.
Other minerals found in various places of Bohemia are copper, sulphur, cobalt, alum, nickel, arsenic and various sorts of precious stone, like the Bohemian garnet (pyrope), and building stone.
Ores containing much arsenic or sulphur are generally roasted at a low heat and the assay is made on the roasted material.
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.
The ore is treated as described in the cyanide method until the copper precipitated by the aluminium foil has been washed and dissolved in 5 cc. of nitric acid; then 0.25 gramme of potassium chlorate is added, and the solution boiled nearly dry to oxidize any arsenic present to arsenic acid.
To celebrate his seventieth birthday his scientific papers were collected and published in two volumes (Gesammelte Werke, Brunswick, 1905), and the names of the headings under which they are grouped give some idea of the range and extent of his chemical work: (1) organic arsenic compounds, (2) uric acid group, (3) indigo, (4) papers arising from indigo researches, (5) pyrrol and pyridine bases, (6) experiments on the elimination of water and on condensation, (7) the phthaleins, (8) the hydro-aromatic compounds, (9) the terpenes, (io) nitroso compounds, (11) furfurol, (12) acetylene compounds and "strain" (Spannungs) theory, (13) peroxides, (14) basic properties of oxygen, (15) dibenzalacetone and triphenylamine, (16) various researches on the aromatic and (17) the aliphatic series.
It is the most malleable and ductile of all metals with the exception of gold: one gramme can be drawn out into a wire 180 metres long, and the leaf can be beaten out to a thickness of 0.0002 5 mm.; traces of arsenic, antimony, bismuth and lead, however, make it brittle.
Thus arsenic, antimony, bismuth, tin or zinc render the metal brittle, so that it fractures under a die or rolling mill; copper, on the other hand, increases its hardness, makes it tougher and more readily fusible.
In such cases quinine is often inferior to arsenic.
Soc., 1877, 25, p. 122), may be obtained by burning the trifluoride in fluorine, from the pentachloride and arsenic trifluoride and from the trifluoride and bromine, the first formed fluorobromide, PF 3 Br 21 decomposing into the pentabromide and pentafluoride: 5PF 3 Br 2 =3PF 5 +2PBr 5.
Iron, copper, lead, mercury, cinnabar, cobalt, nickel, sulphur, arsenic and china clay also occur.
Oxidizing agents, such as arsenic acid, convert it into ellagic acid, C 14 H 8 0 9 +H 2 0, probably a fluorene derivative, a substance which occurs in gall-nuts, in the external membrane of the episperm of the walnut, and prob ably in many plants, and composes the "bezoar stones" found in the intestines of Persian wild goats.
The nitrobenzene may be replaced by arsenic acid, when the reaction proceeds much more quietly and a cleaner product is obtained (C. A.
In the United Kingdom much gas sulphur is used for the manufacture of sulphuric acid, together with a limited quantity of Sicilian sulphur for the production of sulphuric acid free from arsenic.
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.
Towards the end of July sheep are all dipped to protect them from maggot flies (which are generally worst during August) with materials containing arsenic and sulphur, like that of Cooper and Bigg.
The most important mineral is a peculiarly rich argentiferous lead, but gold in small quantities, copper, iron, sulphur, alum and arsenic are also found.
Arsenides, Arsenites, &c. - Several iron arsenides occur as minerals; lolingite, FeAs 2, forms silvery rhombic prisms; mispickel or arsenical pyrites, Fe2AsS2, is an important commercial source of arsenic. A basic ferric arsenite, 4Fe2O3 As2O3.5H 2 O, is obtained as a flocculent brown precipitate by adding an arsenite to ferric acetate, or by shaking freshly prepared ferric hydrate with a solution of arsenious oxide.
ORPIMENT (auripigmentum), arsenic trisulphide, As2S3, or yellow realgar, occurring in small quantities as a mineral crystallizing in the rhombic system and of a brilliant goldenyellow colour in Bohemia, Peru, &c. For industrial purposes an artificial orpiment is manufactured by subliming one part of sulphur with two of arsenic trioxide.
Gold is found in several places, and some arsenic, antimony, bismuth, manganese, mercury and sulphur.
ARSENIC (symbol As, atomic weight 75.0), a chemical element, known to the ancients in the form of its sulphides.
The oxide known as white arsenic is mentioned by the Greek alchemist Olympiodorus, who obtained it by roasting arsenic sulphide.
These substances were all known to the later alchemists, who used minerals containing arsenic in order to give a white colour to copper.
Albertus Magnus was the first to state that arsenic contained a metal-like substance, although later writers considered it to be a bastard or semi-metal, and frequently called it arsenicum rex.
Brandt showed that white arsenic was the calx of this element, and after the downfall of the phlogiston theory the views concerning the composition of white arsenic were identical with those which are now held, namely that it is an oxide of the element.
Arsenic is found in the uncombined condition in various localities, but more generally in combination with other metals and sulphur, in the form of more or less complex sulphides.
Native arsenic is usually found as granular or curvilaminar masses, with a reniform or botryoidal surface.
Crystals of arsenic belong to the rhombohedral system, and have a perfect cleavage parallel to the basal plane; natural crystals are, however, of rare occurrence, and are usually acicular in habit.
Native arsenic occurs usually in metalliferous veins in association with ores of antimony, silver, &c.; the silver mines of Freiberg in Saxony, St Andreasberg in the Harz, and Chanarcillo in Chile being well-known localities.
Arsenic is a constituent of the minerals arsenical iron, arsenical pyrites or mispickel, tin-white cobalt or smaltite, arsenical nickel, realgar, orpiment, pharmacolite and cobalt bloom, whilst it is also met with in small quantities in nearly all specimens of iron pyrites.
The ordinary commercial arsenic is either the naturally occurring form, which is, however, more or less contaminated with other metals, or is the product obtained by heating arsenical pyrites, out of contact with air, in earthenware retorts which are fitted with a roll of sheet iron at the mouth, and an earthenware receiver.
By this method of distillation the arsenic sublimes into the receiver, leaving a residue of iron sulphide in the retort.
It can also be obtained by the reduction of white arsenic (arsenious oxide) with carbon.
An electro-metallurgical process for the extraction of arsenic from its sulphides has also been proposed (German Patent, 67,973).
The arsenic solution is decomposed at the cathode, and the element precipitated there.
It liquefies when heated under pressure, and its melting point lies between 446° C. and 457° C. The vapour of arsenic is of a golden yellow colour, and has a garlic odour.
By condensing arsenic vapour in a glass tube, in a current of an indifferent gas, such as hydrogen, amorphous arsenic is obtained, the deposit on the portion of the tube nearest to the source of heat being crystalline, that farther along (at a temperature of about C.) being a black amorphous solid, while still farther along the tube a grey deposit is formed.
Arsenic burns on heating in a current of oxygen, with a pale lavender-coloured flame, forming the trioxide.
It is easily oxidized by heating with concentrated nitric acid to arsenic acid, and with concentrated sulphuric acid to arsenic trioxide; dilute nitric acid only oxidizes it to arsenious acid.
Arsenic and most of its soluble compounds are very poisonous, and consequently the methods used for the detection of arsenic are very important.
For full accounts of methods used in detecting minute traces of arsenic in foods, &c., see "Report to Commission to Manchester Brewers' Central Association," the Analyst, 1900, 26, p. 8; "Report of Conjoint Committee of Society of Chemical Industry and Society of Public Analysts," the Analyst, 1902, 27, p. 48; T.
Arsenic and arsenical compounds generally can be detected by (a) Reinsch's test: A piece of clean copper is dipped in a solution of an arsenious compound which has been previously acidified with pure hydrochloric acid.
(b) Fleitmann's test and Marsh's test depend on the fact that arsenic and its compounds, when present in a solution in which hydrogen is being generated, are converted into arseniuretted hydrogen, which can be readily detected either by its action on silver nitrate solution or by its decomposition on heating.
A piece of bibulous paper, moistened with silver nitrate, is held over the mouth of the tube, and if arsenic be present, a grey or black deposit is seen on the paper, due to the silver nitrate being reduced by the arseniuretted hydrogen.
Antimony gives no reaction under these conditions, so that the method can be used to detect arsenic in the presence of antimony, but the test is not so delicate as either Reinsch's or Marsh's method.
A blank experiment should always be carried out in testing for small quantities of arsenic, to ensure that the materials used are quite free from traces of arsenic. It is to be noted that the presence of nitric acid interferes with the Marsh test; and also that if the arsenic is present as an arsenic compound it must be reduced to the arsenious condition by the action of sulphurous acid.
Arsenic compounds can be detected in the dry way by heating in a tube with a mixture of sodium carbonate and charcoal when a deposit of black amorphous arsenic is produced on the cool part of the tube, or by conversion of the compound into the trioxide and heating with dry sodium acetate when the offensive odour of the extremely poisonous cacodyl oxide is produced.
In the wet way, arsenious oxide and arsenites, acidified with hydrochloric acid, give a yellow precipitate of arsenic trisulphide on the addition of sulphuretted hydrogen; this precipitate is soluble in solutions of the alkaline hydroxides, ammonium carbonate and yellow ammonium sulphide.
Arsenic is usually estimated either in the form of magnesium pyroarsenate or as arsenic sulphide.
For the pyroarsenate method it is necessary that the arsenic should be in the arsenic condition, if necessary this can be effected by heating with nitric acid; the acid solution is then mixed with "magnesia mixture" and made strongly alkaline by the addition of ammonia.
From the weight of magnesium pyroarsenate obtained the weight of arsenic can be calculated.
In the sulphide method, the arsenic should be in the arsenious form.
Arsenic can also be estimated by volumetric methods; for this purpose it must be in the arsenious condition, and the method of estimation consists in converting it into the arsenic condition by means of a standard solution of iodine, in the presence of a cold saturated solution of sodium bicarbonate.
The atomic weight of arsenic has been determined by many different chemists.
Pelouze (Comptes rendus, 1845, 20, p. 1047) titrated arsenic chloride with silver solution and obtained 75 o; and F.
1861, 113, p. 134) by converting arsenic trisulphide in hydrochloric acid solution into arsenic pentasulphide also obtained 75.0.
Arsenic forms two hydrides: - The dihydride, As2H2, is a brown velvety powder formed when sodium or potassium arsenide is decomposed by water.
Arsenic trihydride (arsine or arseniuretted hydrogen), AsH3, is formed by decomposing zinc arsenide with dilute sulphuric acid; by the action of nascent hydrogen on arsenious compounds, and by the electrolysis of solutions of arsenious and arsenic acids; it is also a product of the action of organic matter on many arsenic compounds.
It easily burns, forming arsenious oxide if the combustion proceeds in an excess of air, or arsenic if the supply of air is limited; it is also decomposed into its constituent elements when heated.
Arsenic tribromide, AsBr3, is formed by the direct union of arsenic and bromine, and subsequent distillation from the excess of arsenic; it forms colourless deliquescent prisms which melt at 20 0 -25° C., and boil at 220° C. Water decomposes it, a small quantity of water leading to the formation of the oxybromide, AsOBr, whilst a large excess of water gives arsenious oxide, As4O6.
Arsenic certainly forms two, or possibly three iodides.
The di-iodide, As2I4 or AsI2 which is prepared by heating one part of arsenic with two parts of iodine, in a sealed tube to 230° C., forms dark cherry red prisms, which are easily oxidized, and are readily decomposed by water.
The tri-iodide, AsI3 prepared by subliming arsenic and iodine together in a retort, by leading arsine into an alcoholic iodine solution, or by boiling powdered arsenic and iodine with water, filtering and evaporating, forms brick-red hexagonal tables, of specific gravity 4.39, soluble in alcohol, ether and benzene, and in a large excess of water; in the presence of a small quantity of water, it is decomposed with formation of hydriodic acid and an insoluble basic salt of the composition 4AsOI.
The pentaiodide, AsI5, appears to be formed when a mixture of one part of arsenic and seven parts of iodine is heated to 190° C., but on dissolving the resulting product in carbon bisulphide and crystallizing from this solvent, only the tri-iodide is obtained.
Arsenic trichloride, AsCl3, is prepared by distilling white arsenic with concentrated sulphuric acid and common salt, or by the direct union of arsenic with chlorine, or from the action of phosphorus pentachloride on white arsenic. It is a colourless oily heavy liquid of specific gravity 2.205 (o° C.), which, when pure and free from chlorine, solidifies at - 18°C., and boils at 132 °C. It is very poisonous and decomposes in moist air with evolution of white fumes.
With a little water it forms arsenic oxychloride, AsOCl, and with excess of water it is completely decomposed into hydrochloric acid and white arsenic. It combines directly with ammonia to form a solid compound variously given as AsCl3.3NH3 or 2AsCl3.7NH3, or AsCl3.4NH3 Arsenic trifluoride, AsF3, is prepared by distilling white arsenic with fluorspar and sulphuric acid, or by heating arsenic tribromide with ammonium fluoride; it is a colourless liquid of specific gravity 2.73, boiling at 63° C; it fumes in air, and in contact with the skin produces painful wounds.
Two oxides of arsenic are definitely known to exist, namely the trioxide (white arsenic), As406, and the pentoxide, As205, while the existence of a suboxide, As20(?), has also been mooted.
Arsenic trioxide has been known from the earliest times, and was called Huettenrauch (furnace-smoke) by Basil Valentine.
It occurs naturally in the mineral claudetite, and can be artificially prepared by burning arsenic in air or oxygen.
White arsenic exists in two crystalline forms (octahedral and prismatic) and one amorphous form; the octahedral form is produced by the rapid cooling of arsenic vapour, or by cooling a warm saturated solution in water, or by crystallization from hydrochloric acid, and also by the gradual transition of the amorphous variety, this last phenomenon being attended by the evolution of heat.
zinc, tin and cadmium) with precipitation of arsenic and formation of arseniuretted hydrogen.
By the action of oxidizing agents such as nitric acid, iodine solution, &c., arsenious acid is readily converted into arsenic acid, in the latter case the reaction proceeding according to the equation H3AsO3 +I2 + H2O = H3AsO4 + 2HI.
Arsenic pentoxide, As2O5, is most easily obtained by oxidation of a solution of arsenious acid with nitric acid; the solution on concentration deposits the compound 2H3AsO4.
This substance dissolves slowly in water, forming arsenic acid; by heating to redness it decomposes into arsenic and oxygen.
It deliquesces in moist air, and is easily reduced to arsenic by heating with carbon.
Arsenic acid, H3AsO4, is prepared as shown above, the compound 2H3AsO4.H2O on being heated to 100° C. parting with its water of crystallization and leaving a residue of the acid, which crystallizes in needles.
The salts of arsenic acid, termed arsenates, are isomorphous with the phosphates, and in general character and reactions resemble the phosphates very closely; thus both series of salts give similar precipitates with "magnesia mixture" and with ammonium molybdate solution, but they can be distinguished by their behaviour with silver nitrate solution, arsenates giving a reddish-brown precipitate,whilst phosphates give a yellow precipitate.
There are three known compounds of arsenic and sulphur, namely, realgar As2S2, orpiment As2S3, and arsenic pentasulphide As2S5.
Realgar occurs native in orange prisms of specific gravity 3.5; it is prepared artificially by fusing together arsenic and sulphur, but the resulting products vary somewhat in composition; it is readily fusible and sublimes unchanged, and burns on heating in a current of oxygen, forming arsenic trioxide and sulphur dioxide.
On acidifying the solution so obtained with hydrochloric acid, the whole of the arsenic is reprecipitated as trisulphide, K2HAsO3 + K2HAsS3 + 4HCl = 4KCl + 3H2O + As2S3.
Arsenic pentasulphide,As2S5, can be prepared by fusing the trisulphide with the requisite amount of sulphur; it is a yellow easily-fusible solid, which in absence of air can be sublimed unchanged; it is soluble in solutions of the caustic alkalis, forming thioarsenates, which can also be obtained by the action of alkali polysulphides on orpiment.
Arsenic compounds containing selenium and sulphur are known, such as arsenic seleno-sulphide, AsSeS2, and arsenic thio-selenide, AsSSe2.
Arsenic phosphide, AsP, results when phosphine is passed into arsenic trichloride, being precipitated as a red-brown powder.
Many organic arsenic compounds are known, analogous to those of nitrogen and phosphorus, but apparently the primary and secondary arsines, AsH2CH3 and AsH(CH3)2, do not exist, although the corresponding chlorine derivatives, AsCl2CH3, methyl arsine chloride, and AsCl(CH3)2, dimethyl arsine chloride, are known.
The chlorides AsCl2CH3 and AsCl(CH3)2 as well as As(CH3)3 are capable of combining with two atoms of chlorine, the arsenic atom apparently changing from the tri- to the penta-valent condition, and the corresponding oxygen compounds can also be oxidized to compounds containing one oxygen atom or two hydroxyl groups more, forming acids or oxides.
==Pharmacology== Of arsenic and its compounds, arsenious acid (dose 6, -, 1 v1 1 5 - gr.) and its preparation liquor arsenicalis, Fowler's solution (dose -8 111.), are in very common use.
This effect is the same however the drug be administered, as, even after subcutaneous injection, the arsenic is excreted into the stomach after absorption, and thus sets up gastritis in its passage through the mucous membrane.
None of these known effects of arsenic is sufficient to account for the profound change that a course of the drug will often produce in the condition of a patient.
According to Binz and Schultz its power is due to the fact that it is an oxygen-carrier, arsenious acid withdrawing oxygen from the protoplasm to form arsenic acid, which subsequently yields up its oxygen again.
But many accidents have resulted from the arsenic being absorbed, and the patient thereby poisoned.
Certain cases of anaemia which do not yield to iron are often much improved by arsenic, though in other apparently similar ones it appears to be valueless.
==Toxicology and Forensic Medicine== The commonest source of arsenical poisoning is the arsenious acid or white arsenic, which in one form is white and opaque, like flour, for which it has been mistaken with fatal results.
Metallic arsenic is probably not poisonous, but as it usually becomes oxidized in the alimentary canal, the usual symptoms of arsenical poisoning follow its use.
The similarity of the symptoms to those of cholera is very marked, but if the suspicion arises it can soon be cleared up by examining any of the secretions for arsenic. More rarely the poison seems to centre itself on the nerve centres, and gastro-intestinal symptoms may be almost or quite absent.
Arsenic may be gradually obsorbed into the system in very small quantities over a prolonged period, the symptoms of chronic poisoning resulting.
In 1900 an outbreak of "peripheral neuritis" with various skin affections occurred in Lancashire, which was traced to beer made from glucose and invert sugar, in the preparation of which sulphuric acid contaminated with arsenic was said to have been used.
Arsenic is found in almost every part of the body, but is retained in largest amount by the liver, secondly by the kidneys.
The detection of arsenic in criminal cases is effected either by Reinsch's test or by Marsh's test, the urine being the secretion analysed when available.
In alkaline solution azobenzene results, while arsenic acid produces the violet-colouring matter violaniline.
It is rich in minerals, including chrome, manganese, zinc, antimony, iron, argentiferous lead, arsenic and lignite, but some of these are unworked.
There are exceptions to this, however, as children are more affected in proportion by opium and some other substances, and less by mercury and arsenic. In old age also the nervous system and the tissues generally do not react so readily as in youth.
It is well known that the habitual consumption of certain drugs, such as tobacco, Indian hemp, opium, arsenic, alcohol and many others, gradually induces a condition of tolerance to their effects, so that large doses can be taken without causing symptoms of poisoning.
Recent researches on arsenic and atropine, however, point to the leucocytes as playing an important part in the production of tolerance, as these gradually become capable of ingesting large amounts of the foreign substances, and thus render them more or less harmless to the tissues, until they are gradually excreted from the body.
- These include iron, manganese, aluminium, chromium, zinc, copper, silver, gold, platinum, lead, mercury, and probably antimony, arsenic and bismuth.
Arsenic and antimony do not form combinations with albumen, but they both greatly depress the central nervous system and circulation; and, if their action be long continued in large doses, they cause fatty degeneration of the viscera and disappearance of glycogen from the liver.
Mineral waters act in the same way, but their effects are very much modified by, and depend largely upon, other constituents, such as alkaline salts, iron, arsenic, sulphides, carbonic acid, &c.
There is a U.S. assayer's office here, and there are extensive shipyards, a large paper mill, iron works, and, just outside the city limits, the smelters of the American Smelters Securities Company, in connexion with which is one of the two plants in the United States for saving arsenic from smelter fumes.
If we thought Howie was upset over the Youngblood matter, it was arsenic versus ice cream compared to how enraged he was over a challenge to his ability.
accidental ingestion of ant killers based on organic arsenic salts.
antimony sulfide, the white is processed arsenic oxide and the yellow-brown in the background is arsenic sulfide ore.
lead arsenate is an inorganic compound of arsenic and found to be useful in the purpose of killing pests.
Tube wells drilled into the ground to provide drinking water safe from cholera were later found to contain naturally occurring arsenic.
The green paint of this period invariably contains arsenic.
It draws gold out of the rocks but also brings out toxic substances including arsenic.
Scientists have modified a plant in the mustard family to remove arsenic from contaminated soils and store it in its leaves for easy disposal.
He investigated the death of one of Mary Ann's stepsons and found arsenic in the boy's stomach.
A market basket survey of inorganic arsenic in food.
Conversely, vegetarians may have lower dietary exposures to chemicals which are more prevalent in meat and fish (e.g. arsenic ).
JECFA has also set a PTWI for inorganic arsenic (but not for organic or for total arsenic ).
Shown a sample of yellow arsenic, he took it in his hand and swallowed it.
arsenic trioxide above.
arsenic poisoning could be confused with cholera.
arsenic contamination cannot properly be laid at their door.
arsenic mitigation project to deal with the issue.
arsenic compounds become well established.
arsenic in food.
arsenic in drinking water.
arsenic in air.
arsenic in rural areas throughout the UK.
arsenic in the diet is fish.
In the first instance the study will be confined to the heavy metals cadmium, lead, arsenic and zinc.
contaminated with arsenic, copper and zinc.
The gender impacts of arsenic contamination of drinking water This document is a collection of three articles addressing the arsenic crisis in Bangladesh.
A cigarette butt contains up to 4,000 chemicals, including hydrogen cyanide and arsenic.
This estimate is somewhat higher than the high-level adult dietary intake of arsenic of 0.42 mg/day estimated from the 1994 TDS.
This estimate is somewhat higher than the high-level adult dietary intake of arsenic of 0.42 mg/day estimated from the 1994 TDS.
The COT considered the implications for human health of arsenic in food in 1995.
We grow layers of crystals containing indium, phosphorus, gallium and arsenic on wafers of indium phosphide.
inorganic arsenic in food.
melodic, rhythmically deft electronica with arsenic.
metalloid arsenic are phytotoxic to plants as well as injurious to human health.
And the white lines on her fingernails are the telltale sign of her killer's modus operandi: arsenic poisoning.
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