Electrical Engineering Testing: A Practical Work for Second and Third Year Students, Engineers and Others

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Chapman and Hall, 1902 - Electric engineering - 474 pages

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Page 322 - 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 twenty-four hours before sealing, which should be done as follows.
Page 320 - Prepare a neutral saturated solution of pure ("pure recrystallised ") 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. 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.
Page 321 - O'5 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 321 - ... taking care that the whole of the exposed platinum is covered. Shake up the paste and introduce it without contact with the upper part of the walls of the test tube, filling the tube above the mercury to a depth of rather more than 1 centimetre.
Page 320 - ... 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 mercurous sulphate.
Page 354 - ... scale shows, approximately enough for most purposes, the strength of the current ; the notches in the top of the aluminium scale show the precise position of the weight corresponding to each of the numbered divisions on the fixed scale, which practically annuls error of parallax due to the position of the eye. When the pointer is not exactly below one of the notches corresponding to integral divisions of the inspectional scale, the proportion of the space on each side to the space between two...
Page 415 - The whole instrument, as said above, rests on three vulcanite legs attached to the base plate of system A ; and two terminals are provided, one, i, on the base of system A, and the other, j, on the end of one of the corner bolts of system B. The air leyden which has been thus described is used as a standard of electrostatic capacity.
Page 320 - Take mercurous sulphate, purchased as pure, and wash it thoroughly with cold distilled water by agitation in a bottle ; drain off the water, and repeat the process at least twice.
Page 321 - 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 stock bottle, and repeat the whole process. This method ensures the formation of a saturated solution of zinc and mercurous sulphates in water.
Page 366 - ... plates and situated midway between them. The upper end of this movable plate has a fine prolongation which serves as a pointer for indicating the deflections on the scale of the instrument, and at its lower end is fixed a knife edge having its length perpendicular to the plane in which the plate moves. When the fixed and movable plates are connected respectively to two points of an electric circuit between which there exists a difference of potential, the movable plate tends to move so as to...

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