(7) Electrolytic. - This method consists in decomposing a solution of a salt of the metal by the electric current and weighing the metal deposited at the cathode.
In light Kundt's name is widely known for his inquiries in anomalous dispersion, not only in liquids and vapours, but even in metals, which he obtained in very thin films by means of a laborious process of electrolytic deposition upon platinized glass.
A third class of electric wave detector depends upon the power of electric oscillations to annul the electrolytic polarization of electrodes of small surface immersed in an electrolyte.
This increases the resistance of the electrolytic cell.
If, however, one electrode of this cell is connected to the earth and the other to a receiving antenna and electric waves allowed to fall on the antenna, the oscillations passing through the electrolytic cell will remove the polarization and L temporarily decrease the resistance of the cell.
Schloemilch 19 and others, and are known as electrolytic detectors.
The receiving arrangements comprised also an open or antenna circuit connected directly with a closed condenser-inductance circuit, but in place of the spark gap in the transmitter an electrolytic receiver was inserted, having in connexion with it as indicator a voltaic cell and telephone.
At the receiving station the differences in these systems depend chiefly upon variations in the actual form of the oscillation detector used, whether it be a loose contact or a thermal, electrolytic or magnetic detector.
Klaproth in 1799, is obtained when pure carbon (graphite or charcoal) is oxidized by alkaline permanganate, or when carbon forms the positive pole in an electrolytic cell (Ber., 1883, 16, p. 1209).
Wolcott Gibbs worked out the electrolytic separation of copper in 1865.
(5) Colorimetric. - This method is adopted when it is necessary to determine minute traces (as in the liquid obtained in the electrolytic separation of copper) of substances which afford well-defined colour reactions.
The first exact quantitative study of electrolytic phenomena was made about 1830 by Michael Faraday (Experimental Researches, 1833).
1) through two branches containing the two electrolytic cells A and B.
Kohlrausch formulated a theory of electrolytic conduction based on the idea that, under the action of the electric forces, the oppositely charged ions moved in opposite directions through the liquid, carrying their charges with them.
Again, water, the best electrolytic solvent known, is also the body of the highest specific inductive capacity (dielectric constant), and this property, to whatever cause it may be due, will reduce the forces between electric charges in the neighbourhood, and may therefore enable two ions to separate.
This view of the nature of electrolytic solutions at once explains many well-known phenomena.
An interesting relation appears when the electrolytic conductivity of solutions is compared with their chemical activity.
Moreover, a study of the chemical relations of electrolytes indicates that it is always the electrolytic ions that are concerned in their reactions.
Arrhenius has pointed out that the coefficient of affinity of an acid is proportional to its electrolytic ionization.
We may take it, then, that only that portion of these bodies is chemically active which is electrolytically active - that ionization is necessary for such chemical activity as we are dealing with here, just as it is necessary for electrolytic conductivity.
But the ions of an electrolytic solution can move independently through the liquid, even when no current flows, as the consequences of Ohm's law indicate.
C. Jones, The Theory of Electrolytic Dissociation (New York, 1900); N.
Some of the more important papers on the subject have been reprinted for Harper's Series of Scientific Memoirs in Electrolytic Conduction (1899) and the Modern Theory of Solution (1899).
The electrolytic reduction of the aromatic nitro compounds gives rise to substituted hydroxylamines which are immediately transformed into aminophenols or amines.
The earliest is that of Quincke, who coated a glass grating with a chemical silver deposit, subsequently thickened with copper in an electrolytic bath.
It is best to commence the electrolytic thickening in a silver acetate bath.
In the absence of metallic tin there is no visible change; but, as soon as the metal is introduced, an electrolytic action sets in and the articles get coated over with a firmly adhering film of tin.
Borchers, trace it to the presence of oxide, produced, for example, either by the use of a solution containing a trace of basic salt of zinc (to prevent which the bath should be kept just - almost imperceptibly - acid), or by the presence of a more electro-negative metal, which, being co-deposited, sets up local action at the expense of the zinc. Many processes have been patented, the ore being acted upon by acid, and the resulting solution treated, by either chemical or electrolytic means, for the successive removal of the other heavy metals.
30) obtained potassium by the electrolysis of a mixture of potassium and calcium chlorides fused over a lamp. There are here foreshadowed two types of electrolytic furnace-operations: (a) those in which external heating maintains the electrolyte in the fused condition, and (b) those in which a currentdensity is applied sufficiently high to develop the heat necessary to effect this object unaided.
In ordinary electrolytic work only the continuous current may of course be used, but in electrothermal work an alternating current is equally available.
It was found in practice (in 1889) that the expenditure of energy per pound of reduced aluminium was about 23 H.P.-hours, a number considerably in excess of that required at the present time for the production of pure aluminium by the electrolytic process described in the article Aluminium.
Since that date other processes have been devised and the electrolytic processes have entirely replaced the older methods of reduction with sodium.
Methods have also been discovered for the electrolytic manufacture of calcium, which have had the effect of converting a laboratory curiosity into a product of commercial importance.
The principle usually followed in the electrolytic refining of metals is to cast the impure metal into plates, which are exposed as anodes in a suitable solvent, commonly a salt of the metal under treatment.
Similarly, the formation of organic halogen products may be effected by electrolytic chlorine, as, for example, in the production of chloral by the gradual introduction of alcohol into an anode cell in which the electrolyte is a strong solution of potassium chloride.
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.
Peters has found that with these methods the best results are obtained when ozone is employed in addition to electrolytic oxygen.
(Leipzig, 1900); Gore, The Art of Electrolytic Separation of Metals (London, 1890); Blount, Practical Electro-Chemistry (London, 1906); G.
A group of bodies may, however, be yet discovered between alloys and electrolytes in which evidence may be found of some gradual change from wholly metallic to electrolytic conduction.
For electrolytic precipitation the solution may contain up to 0.1% KCN.
In the Transvaal the operation occupies 32 to 4 days for fine sands, and up to 14 days for coarse sands; the quantity of cyanide per ton of tailings varies from 0.26 to 0.28 lb, for electrolytic precipitation, and o 5 lb for zinc precipitation.
- The electrolytic separation of the gold from cyanide solutions was first practised in the Transvaal.
Many variations of the electrolytic process as above outlined have been suggested.
The methods of parting can be classified into "dry," "wet" and electrolytic methods.
In the " dry " methods the silver is converted into sulphide or chloride, the gold remaining unaltered; in the " wet " methods the silver is dissolved by nitric acid or boiling sulphuric acid; and in the electrolytic processes advantage is taken of the fact that under certain current densities and other circumstances silver passes from an anode composed of a gold-silver alloy to the cathode more readily than gold.
Miller's chlorine process is of any importance, this method, and the wet process of refining by sulphuric acid, together with the electrolytic process, being the only ones now practised.
It is especially suitable to gold containing little silver and base metals - a character of Australian gold - but it yields to the sulphuric acid and electrolytic methods in point of economy.
It is applicable to any alloy, and is the best method for parting gold with the exception of the electrolytic method.
The electrolytic parting of gold and silver has been shown to be more economical and free from the objections - such as the poisonous fumes - of the sulphuric acid process.
von Riemsdijk) and 270.5° (C. C. Person); commercial bismuth melts at 260° (Ledebur), and electrolytic bismuth at 264° (Classen).
Electrolytic or ionic dissociation is the separation of a substance in solution into ions.
whether continuous current or alternating current, and if the latter, whether monophase or polyphase; (ii) according to whether they record intermittently or continuously; (iii) according to the principle of their action, whether mechanical or electrolytic; (iv) according to the nature of the measurement, whether quantity or energy meters.
Most of the practical meters in use at the present time may be classified under the following five heads: electrolytic meters, motor meters, clock meters, intermittent registering meters and induction meters.
Electrolytic Meters are exclusively ampere-hour meters, measuring electric quantity directly and electric energy only indirectly, on the assumption that the pressure of the supply is constant.
The first electrolytic house meter in connexion with public electric supply was described by St.
It consisted of a glass vessel, containing a solution of sulphate of zinc, in which were placed two plates of pure amalgamated zinc. These plates were connected by means of a german-silver shunt, their size and the distance between them being so adjusted that about ii 0 - 0 - part of the current passing through the meter travelled through the electrolytic cell and -j o i j of the current passed through the shunt.
The shunted voltameter was then inserted in series with the electric supply mains leading to the house or building taking electric energy, and the current which passed dissolved the zinc from one plate and deposited it upon the other, so that after a certain interval of time had elapsed the altered weight of the plates enabled the quantity of electricity to be determined from the known fact that an electric current of one ampere, flowing for one hour, removes 1.2533 grammes of zinc from a solution of sulphate of zinc. Hence the quantity in amperehours passing through the electrolytic cell being known and the fraction of the whole quantity taken by the cell being known, the quantity supplied to the house was determined.
To prevent temperature from affecting the shunt ratio, Edison joined in series with the electrolytic cell a copper coil the resistance of which increased with a rise of temperature by the same amount that the electrolyte decreased.
The whole current supplied to the house flows through an electrolytic cell consisting of a glass tube containing two platinum electrodes; the electrolyte is dilute sulphuric acid covered with a thin layer of oil to prevent evaporation.
A third electrolytic meter of the shunted voltameter type is that of A.
In the Long-Schattner electrolytic meter a solution of sulphate of copper is electrolyzed.
In the Long-Schattner electrolytic meter, the insertion of the coin depresses a copper plate or plates into an electrolytic cell containing a solution of sulphate of copper; the passage of the current dissolves the copper off one of the plates, the loss in weight being determined by the quantity of the electricity passed.
The electrolytic isolation of calcium has been carefully investigated, and this is the method followed for the commercial production of the metal.
- Calcium hydride, obtained by heating electrolytic calcium in a current of hydrogen, appears in commerce under the name hydrolite.
The U-shaped electrolytic vessel and the electrodes are made of an alloy of platinum-iridium, the limbs of the tube being closed by stoppers made of fluor-spar, and fitted with two lateral exit tubes for carrying off the gases evolved.
In 1886, however, Castner replaced the carbonate by caustic soda, and materially cheapened the cost of production; but this method was discarded for an electrolytic one, patented by Castner in 1890.
Electrolytic processes had, in fact, been considered since 1851, when Charles Watt patented his method for the production of sodium and potassium from fused chlorides.
Electrolytic processes have also been devised.
It may also be prepared by heating a mixture of carbon, oxide of iron and magnesite to bright redness; and by heating a mixture of magnesium ferrocyanide and sodium carbonate, the double cyanide formed being then decomposed by heating it with metallic zinc. Electrolytic methods have entirely superseded the older methods.
During his first period of discovery, besides the induction of electric currents, Faraday established the identity of the electrification produced in different ways; the law of the definite electrolytic action of the current; and the fact, upon which he laid great stress, that every unit of positive electrification is related in a definite manner to a unit of negative electrification, so that it is impossible to produce what Faraday called "an absolute charge of electricity" of one kind not related to an equal charge of the opposite kind.
Now measurements of osmotic properties of these solutions show that their osmotic pressures are abnormally great and that, at extreme dilution, the ratio of their osmotic pressures to that of equivalent solutions of non-electrolytes is equal to the number of ions indicated by the electrolytic properties.
From the osmotic side also, then, electrolytic dissociation is indicated, and indeed, it was from this side that the idea was first suggested by S.
In 1808 Sir Humphry Davy, fresh from the electrolytic isolation of potassium and sodium, attempted to decompose alumina by heating it with potash in a platinum crucible and submitting the mixture to a current of electricity; in 1809, with a more powerful battery, he raised iron wire to a red heat in contact with alumina, and obtained distinct evidence of the production of an iron-aluminium alloy.
His attention was at first divided between two processes - the chemical method of reducing the chloride with potassium, and an electrolytic method of decomposing it with a carbon anode and a platinum cathode, which was simultaneously imagined by himself and R.
It was soon discovered that the faculty of inducing dissociation possessed by the current might now be utilized with some hope of pecuniary success, but as electrolytic currents are of lower voltage than those required in electric furnaces, molten alumina again became impossible.
Pechiney till the advent of the present electrolytic process rendered it no longer profitable.
Cratzel patented a useless electrolytic process with fused cryolite or the double chloride as the raw material, and in 1886 Dr E.
Commercial electrolytic aluminium of the best quality contains as the average of a large number of tests, 0.48% of silicon and 0.46% of iron, the residue being essentially aluminium itself.
It must be remembered, too, that electrolytic aluminium only became known during the last decade of the 19th century.
Much has yet to be learnt about the practical qualities of the electrolytic product, and although every day's experience serves to place the metal in a firmer industrial position, a final verdict can only be passed after the lapse of time.
The potassium salt, KMnO 4, may be prepared by passing chlorine or carbon dioxide through an aqueous solution of potassium manganate, or by the electrolytic oxidation of the manganate at the anode [German patent 101710 (1898)].
the Leblanc, the ammonia-soda, and the electrolytic processes.
- In this place we speak only of the preparation of chlorine from hydrochloric acid by chemical processes; the electrolytic processes will be treated hereafter.
It is true that all the chlorine combined with the sodium is lost partly as NaC1 and partly as CaC1 2; none of the innumerable attempts at recovering the chlorine from the waste liquor has been made to pay, and success is less likely than ever since the perfection of the electrolytic processes.
It stands to reason that the electrolytic processes have been principally developed in localities where the electric current can be produced in the cheapest possible manner by means of water power, but this is not the only condition to be considered, as the question of freight to a centre of consumption and other circumstances may also play an important part.
The products of its electrolytic reduction vary with the conditions: in sulphuric acid solution it yields para-aminophenol (L.
For an electrolytic method of treating mattes, see T.
More recently, owing to the production of caustic soda by electrolytic methods, much chlorine has consequently been produced in the same manner (see Alkali Manufacture).
Sodium hypochlorite can be prepared by the electrolysis of brine solution in the presence of carbon electrodes, having no diaphragm in the electrolytic cell, and mixing the anode and cathode products by agitating the liquid.
The modern process consists in the electrolysis of a hot solution of potassium chloride, or, preferably, the formation of sodium chlorate by the electrolytic method and its subsequent decomposition by potassium chloride.
Sodium chlorate, NaC10 3, is prepared by the electrolytic process; by passing chlorine into milk of lime and decomposing the calcium chlorate formed by sodium sulphate; or by the action of chlorine on sodium carbonate at low temperature (not above 35° C.).
In 1806 Davy communicated to the Royal Society of London a celebrated paper on some " Chemical Agencies of Electricity," and after providing himself at the Royal Institution of London with a battery of several hundred cells, he announced in 1807 his great discovery of the electrolytic decomposition of the alkalis, potash and soda, obtaining therefrom the metals potassium and sodium.
In the 7th series (1834) he defines a number of new terms, such as electrolyte, electrolysis, anode and cathode, &c., in connexion with electrolytic phenomena, which were immediately adopted into the vocabulary of science.
2% of silver, it is still treated by the Ziervogel wet method of extraction, the management dreading the loss which might occur in the Bessemer process of concentration, applied as preliminary to electrolytic separation.
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.
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.
Siemens and Halske introduced a combined process in which the ore, after being part-roasted, is leached by solutions from a previous electrolytic operation, and the resulting copper solution electrolysed.
The recovery of these valuable metals has contributed in no small degree to the expansion of electrolytic refining.
Rickard, Pyrite Smelting (1905); for wet methods, see Eissler, Hydrometallurgy of Copper (London, 1902); and for electrolytic methods, see T.
The fire assay for copper ores was abandoned years ago and the electrolytic method took its place; this in turn is now largely replaced by volumetric methods.
In the electrolytic method from o 5 to 5 grammes of ore are treated in a flask or beaker, with a mixture of io cc. of nitric and ro cc. of sulphuric acid, until thoroughly decomposed.
On this foil the copper in the solution is all precipitated by electrolytic action in a few minutes, and the aluminium is dissolved by the addition of an excess of sulphuric acid.
To eliminate these impurities, electrolytic methods have been devised; of these that of Moebius is the most important and will be described in detail.
Acidified copper nitrate solution is run into this cell, copper is deposited, and the more or less spent solution then passes through the linen partition, and, taking up metal from the anodes by electrolytic solution, is run out of the trough through a series of vessels filled with copper by which the silver is precipitated by simple exchange; after acidification the resulting silver-free copper solution is returned to the cathode cell for the deposition of the copper, the solution being employed again and again until too impure for use.
A year after this paper, which gained him from the French Institute the medal offered by Napoleon for the best experiment made each year on galvanism, he described in his second Bakerian lecture the electrolytic preparation of potassium and sodium, effected in October 1807 by the aid of his battery.
Ostwald, among other chemists, in support of the hypothesis of electrolytic dissociation in solutions.
The alternating current is generally used, the action not being electrolytic. One of the special advantages of the electrical over the older process is that the distilling vessels have a longer life, owing to the fact that they are not externally heated, and so subjected to a relatively high temperature when in contact with the corrosive slag formed in the process.
Medellin, the capital of Antioquia, is provided with an electrolytic refining establishment, several assaying laboratories, and a mint.
Cyclo-hexanone, C 6 H 10 0, is obtained by the distillation of calcium pimelate, and by the electrolytic reduction of phenol, using an alternating current.
By the electrolytic reduction of pseudopelletierine, N-methyl granatanine is obtained, and this by exhaustive methylation is converted into A O des-dimethyl granatanine.
Chem., 1902, 31, p. 289) patented an electrolytic process, wherein 50% sulphuric acid is treated in a divided cell provided with a cathode of amalgamated lead, 50% nitric acid being gradually run into the cathode compartment.
It also appears as an intermediate product in the electrolytic reduction of nitrobenzene in sulphuric acid solution.
Many complex derivatives are known, such, for example, as phosphor-vanadates, arsenio-vanadates, tungsto-vanadates, molybdovanadates, &c. For the use of this oxide in the electrolytic oxidation and reduction of organic compounds, see German Patents 172654 (1903) and 183022 (1905).
This would necessitate chemical action at the junction when a current passed through it, as in an electrolytic cell, whereas the action appears to be purely thermal, and leads to a consistent theory on that hypothesis.
Others have considered conduction in a metal to be analogous to electrolytic conduction, and the observed effects to be due to " migration of the ions."
In Electrolytic cleaning, the metal is made the anode or cathode and is submerged into an electrolytic acid solution.
A bad hum usually means that the main electrolytic capacitors have come to the end of the road.
Spray given off from vessels at which an electrolytic chromium process is carried on, except trivalent chromium.
dissolved copper enriched solution is circulated to the machine and a current is connected to form an electrolytic cell.
One process involves the electrolytic deposition of tin on to ferrous materials.
The electrolytic extraction of sodium Sodium, like many reactive metals, can be extracted by electrolysis of its molten chloride.
electrolytic capacitors have come to the end of the road.
electrolytic deposition of nickel to forma corrosion barrier or to reclaim a worn part.
electrolytic cell by Edmond Becquerel in 1839.
electrolytic action is not required in this process.
electrolytic dissociation of water molecules to hydrogen and oxygen with membrane separation.
Roithner, Monats., 1896, 17, p. 172); by the fusion of 0-aminopropionic acid with urea; by the electrolytic reduction of barbituric acid (J.
Arrhenius is specially associated with the development of the theory of electrolytic dissociation, and his great paper on the subject, Recherches sur la conductibilite galvanique des electrolytes - (1) conductibilite galvanique des solutions aqueuses extremement diluees, (2) theorie chimique des electrolytes, was presented to the Stockholm Academy of Sciences in 1883.
He was subsequently continuously engaged in extending the applications of the doctrine of electrolytic conduction in relation not only to the problems of chemical action but also, on the supposition that in certain conditions the air conducts electrolytically, to the phenomena of atmospheric electricity.
If in a vessel of nitric acid are placed a large platinum plate and a platinum electrode of very small surface such as that produced when an extremely fine platinum wire is slightly immersed in the liquid, and if a current from a single voltaic cell is passed through the electrolytic cell so that the fine wire is the anode or positive pole, then the small surface will be polarized or covered with a film of gas due to electrolysis (fig.
This may be detected by putting a telephone in series with the electrolytic cell, and then on the impact of the electric waves a sound is heard in the telephone due to the sudden increase in the current through it.
This has been achieved by employing a microphone transmitter at the sending end to vary the amplitude but not the wave-length of the emitted waves, and at the receiving end using an electrolytic receiver, which proves to be not merely a qualitative but also a quantitative instrument, to make these variations audible on a telephone.
Chem., 1891, I, p. 364), by the electrolytic reduction of cadmium oxide in potassium cyanide solution, obtained as a mean value 112.055.
This conclusion is supported also by the evidence supplied by the phenomena of electrolytic conduction (see Conduction, Electric, § Ii.).
Mag., 1894, 38, 488) used a little spiral of the pure electrolytic bismuth wire prepared by Hartmann and Braun; this was placed between the pole-pieces of an electromagnet and subjected to fields of various strengths up to nearly 39,000 units.
solely as a heating agent; these are termed electrothermal, as distinguished from electrolytic. In certain electrothermal processes (e.g.
It is obvious that electrolytic iodine and bromine, and oxygen compounds of these elements, may be produced by methods similar to those applied to chlorides (see Alkali Manufacture and Chlorates), and Kellner and others have patented processes with this end in view.
von Riemsdijk) and 270.5Ã‚° (C. C. Person); commercial bismuth melts at 260Ã‚° (Ledebur), and electrolytic bismuth at 264Ã‚° (Classen).
Electrolytic or ionic dissociation is the separation of a substance in solution into ions (see Electrolysis; Solution).
A more modern type of electrolytic meter is that due to C. O.
Elektrochem., 1895, 2, P. 394) recommends the electrolytic preparation from carnallite; the mineral should be freed from water and sulphates.
In the case of electrolytes we can go further, and calculate the diffusion constant itself from the theory of electrolytic dissociation (see Electric conduction, § In Liquids).
Sodium chlorate, NaC10 3, is prepared by the electrolytic process; by passing chlorine into milk of lime and decomposing the calcium chlorate formed by sodium sulphate; or by the action of chlorine on sodium carbonate at low temperature (not above 35Ã‚° C.).
Ferric sulphate is only used as an auxiliary to the weathering process and in an electrolytic process.
This increase in value permits of copper with not over £2 or $to worth of the precious metals being profitably subjected to electrolytic treatment.
Electrolytic methods, in which a solution of antimony sulphide in sodium sulphide is used as the electrolyte, have been proposed (see German Patent 67973, and also Borcher's Electro-Metallurgie), but do not yet appear to have been used on the large scale.
It is also produced in the electrolytic oxidation of N-nitroso piperidine in sulphuric acid solution (F.
Heathcote and others regard the passivity as invariably due to electrolytic action (see papers in the Zeit.
Quantitative methods are divided into four groups, which we now pass on to consider in the following sequence: (a) gravimetric, (0) volumetric, (7) electrolytic, (5) colorimetric.
Hall, by devising the electrolytic method now in use, inaugurated the present era of industrial electrolysis.
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