Outlines of Electrical Engineering |
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acid alternating current ammeter ampere turns armature arrangement back E.M.F. battery brake brush busbars cable carbon carried cast cell cent centimetre circuit coil commutator conductor connected continuous current copper core curve density diagram diameter direction disc dynamo eddy currents effect electric employed flux force galvanometer give given heat hence hysteresis inch induction motor instrument insulation iron kilowatts lamp length load loss machine magnetic field magnetising magnetomotive force material means measured metal meter method mould obtained ohms operation ordinary phase placed plaster plates plug pole position potential pressure resistance result revolutions per minute ring rotor secondary self-induction shown in Fig shunt single-phase slip rings slots solution speed spring stator steel strip sulphate supply surface switch temperature terminals three-phase tion torque transformer tube voltage voltmeter volts wattmeter watts winding wire wound zinc
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Page 60 - O5 cm. thick to fit the tube; at one side of the cork bore a hole through which the zinc rod can pass tightly; at the other side bore another hole for the glass tube which covers the platinum wire; at the edge of the cork cut a nick through which the air can pass when the cork is pushed into the tube.
Page 60 - Sulphate. — Take mercurous sulphate, purchased as pure, mix with it a small quantity of pure mercury, and wash the whole thoroughly with cold distilled water by agitation in a bottle ; drain off the water, and repeat the process at least twice. After the last washing, drain off as much of the water as possible.
Page 60 - ... to neutralise any free acid. The crystals should be dissolved with the aid of gentle heat, but the temperature to which the solution is raised should not exceed 30° C. Mercurous sulphate treated as described in 3 should be added in the proportion of about 12 per cent, by weight of the zinc sulphate crystals to neutralise any free zinc oxide remaining, and the solution filtered, while still warm, into a stock bottle.
Page 60 - Prepare a neutral saturated solution of pure (" pure re-crystallised ") zinc sulphate by mixing in a flask distilled water with nearly twice its weight of crystals of pure zinc sulphate, and adding zinc oxide in the proportion of about 2 per cent, by weight of the zinc sulphate crystals to neutralise any free acid.
Page 60 - Contact is made with the mercury by means of a platinum wire about No. 22 gauge. This is protected from contact with the other materials of the cell by being sealed into a glass tube. The ends of the wire project from the ends of the glass tube ; one end forms the terminal, the other end and a portion of the glass tube dip into the mercury.
Page 60 - Then insert the cork and zinc rod, passing the glass tube through the hole prepared for it. Push the cork gently down until its lower surface is nearly in contact with the liquid. The air will thus be nearly all expelled, and the cell should be left in this condition for at least 24 hours before sealing, which should be done as follows : — Melt some marine glue until it is fluid enough to pour by its own weight, and pour it into the test tube above the cork, using sufficient to cover completely...
Page 60 - ... saturation, and a small quantity of pure mercury. Shake these up well together to form a paste of the consistence of cream. Heat the paste, but not above a temperature of 30° C. Keep the paste for an hour at this temperature, agitating it from time to time, then allow it to cool ; continue to shake it occasionally while it is cooling. Crystals of zinc sulphate should then be distinctly visible, and should be distributed throughout the mass ; if this is not the case, add more crystals from the...
Page 61 - ... hours before sealing, which should be done as follows. Melt some marine glue until it is fluid enough to pour by its own weight, and pour it into the test-tube above the cork, using sufficient to cover completely the zinc and soldering. The glass tube containing the platinum wire should project some way above the top of the marine glue. The cell may be sealed in a more permanent manner by coating the marine glue, when it is set...
Page 59 - To secure purity it should be first treated with acid in the usual manner and subsequently distilled in vacua. 2. The Zinc. — Take a portion of a rod of pure redistilled zinc, solder to one end a piece of copper wire, clean the whole with glass paper, carefully removing any loose pieces of the zinc. Just before making up the cell dip the zinc into dilute sulphuric acid, wash with distilled water, and dry with a clean cloth or filter paper. 3. The Zinc Sulphate Solution. — Prepare a saturated...
Page 61 - The glass tube containing the platinum wire should project some way above the top of the marine glue. The cell thus set up may be mounted in any desirable manner. It is convenient to arrange the mounting so that the cell may be immersed in a water bath up to the level of, say, the upper surface of the cork. Its temperature can then be determined more accurately than is possible when the cell is in air.