Ampere Apparatus

Throughout his life Pasch was interested in using chemical knowledge for practical purposes. He owned an acetic acid factory, and was involved in many minor projects that can be characterized as applied chemistry. His scientific interest was manifested in the purchase of an Ampere apparatus for electromagnetic research at the Vetenskapsakademien, and in experimenting with a Faraday apparatus. When he did pure science he did physics, when he did applied science he did chemistry. 

Based on the general scenario provided above, the analytical method to determine transference or transport numbers has been devised and is carried out in an apparatus which can essentially be regarded as an improvement over the Hittorf apparatus. This consists of two vertical tubes connected together with a U-tube in the middle all three tubes are provided with stop-cocks at the bottom. The U-tube is also provided with stop-cocks at the top by closing these, the solutions in the cathode and anode limbs can be isolated. The silver anode is sealed in a glass tube as shown, and the cathode is a piece of freshly silvered silver foil. The apparatus is filled up with a standard solution of silver nitrate and a steady current of about 0.01 ampere is passed for 2-3 hours. In order to avoid the occurrence of too large a change in concentration it is necessary to pass the current only for a short duration. The... 

The apparatus for this preparation consists of a narrow glass beaker, or a wide-mouthed bottle. The beaker is corked, and an efficient glass stirrer passing through the centre is attached to a small turbine or motor. Pour electrodes are fixed in position so that they are clear of the stirrer. Two anodes, each of sheet platinum of about 1 sq. dcm. surface, are placed diametrically opposite one another, while the two cathodes, spirals of platinum wife and each of 2 cms. surface, are placed between them near the sides of the beaker. 50 gms. toluene, 200 c.cs. of 10% sulphuric acid and 250 c.cs. of acetone are placed in the cell, which is surrounded by cold water. The current density should be 1-5—2 amperes, the E.M.F. 5—6 volts, and the temperature at 15°—20°. The stirring must be vigorous to keep the mixture in a thorough emulsion. 

The current may be drawn from a commercially available battery charger (Note 4) or from a storage battery, each capable of operating at about 6 volts. Experiment has shown that the considerable ripple in the output of the charger has no adverse effect on the reduction. A transformer in the input to the charger, or a variable resistance in the battery circuit, and a 0-3 ampere range d.c. ammeter complete the apparatus. 

The anode compartment is filled and the cathode compartment partially filled with pure dilute sulphuric add (1 8) and a current of about 3-5 amperes passed for about 5 minutes to expel all the air from the apparatus, which is best kept cool by standing in a fairly large vessel of water. The... 

The coulomb (C) is the standard unit of quantity of electric charge. It is defined as the quantity of electricity transported in one second by a current of one ampere. It corresponds to the amount of electricity that will deposit 0.00111798 gof silver in an apparatus set up for plating silver. 

Figure E38-2. Apparatus for this experiment. (A) cover plate. (B) electrode. (C) baffles. (D) acetate strip. (E) agarose layer. (F) sample spot. (G) electrode plugin. (H) buffer. (I) leveling screws. (J) electrical connections. (K) power supply. (L) amperes. (M) volts. (N) coarse adjust. (O) fine adjust. (P) main switch. (Q,S) output plugs. (R) pilot light. (T) polarity switch.

Faraday in his diary says Ampere, Clement, and Desormes came this morning [23 November 1813] to show Sir H. Davy a new substance, discovered, about two years ago, by M. Courtois, saltpetre manufacturer. The process by which it is obtained is not yet publicly known. It is said to be procured from a very common substance, and in considerable quantities . Very little information would seem to have been given to Davy, who at first (says Faraday) thought it was a compound of chlorine and an unknown body, although the entry for the same day says Davy now thinks it contains no chlorine . On I December, Faraday says, Davy had made many experiments on it with his travelling apparatus M. Clement has lately read a paper on it... in which he says it is procured from the ashes of sea-weeds by lixiviation and treatment with sulphuric acid. He conceives it to be a new supporter of combustion. On 3 December, Davy was working on it in Chevreul s laboratory and on ii December he concluded that as yet it must be considered as a simple body . 

The mineral fluorspar had been used as a flux since the middle ages (the name comes from the Latin meaning yZow), and in the Traite Lavoisier had included the fluoric radical as a simple substance (element) as yet unknown. Scheele obtained hydrofluoric acid in 1771. In 1813 Ampere pointed out the many similarities between the fluoric and muriatic (chlorine) compounds. He suggested the unknown element be called fluorine, and in the same year Humphry Davy tried to prepare it by the electrolysis of hydrofluoric acid. The corrosive nature of the acid presented insuperable problems, and it was to be another 73 years before the isolation of the element was achieved. During that time the toxic nature of fluorine compounds was to be responsible for the deaths of at least two chemists and was to ruin the health of many more. Success was finally achieved by Henri Moissan (1852-1907), who electrolysed potassium fluoride dissolved in anhydrous hydrofluoric acid using platinum apparatus. 

For an electrical current (measured in amperes) to flow in a circuit it requires pressure (measured in voltage). As it flows it encounters resistance from the circuit and apparatus and this characteristic is measured in ohms. 

Apparatus.—The Working Cell.—As working cell A, one must employ a cell with a greater e.m.f. than is to be measured. Since in all cases to be studied here, the e.m.f. is less than 2 volts, the most convenient working cell to use is a lead accumulator, which, when fully charged, has an e.m.f. of somewhat over 2 volts. In order that the cell shall not nm down too rapidly, and the e.m.f. therefore, fell, an accumulator of fairly large capacity should be employed. Where large fixed cells are not available, a portable accumulator of 30 to 40 ampere-hours capacity is very suitable. 

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