Bell Hangers' Hand-book

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Electrician Publishing Company, 1889 - Electric alarms - 105 pages

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Page 5 - No single battery fulfills all these conditions, however, and, as we have already intimated, some batteries are better for one purpose and some for another. Thus, for telegraphing through a long line of wire, a considerable internal resistance is of no great consequence, as it is but a small fraction of the total resistance in circuit. For electric gas lighting or other low resistance circuits, on the other hand, much internal resistance would be, if not absolutely fatal, certainly a positive disadvantage.
Page 17 - Instead of employing a porous cell to keep the two liquids separate, it is possible, where one of the liquids is heavier than the other, to arrange that the heavier liquid shall form a stratum at the bottom of the cell, the lighter floating upon it.
Page 2 - It shirts from the positive zinc plate, flows through the fluid to the copper plate, and through the external circuit and back to the zinc plate. The copper strip, whence the current starts on its journey through . the external circuit, is called the positive pole [ + ] and the zinc strip is called the negative pole [ — ]. When the external circuit is broken no current flows, but still the wire connected to the positive pole (copper plate) is called the positive wire, and the wire connected to...
Page 18 - Blue vitriol should be dropped into the jar as it is consumed, care being taken that it goes to the bottom and not on the zinc. The need of the blue vitriol is shown by the fading of the blue color, which should be kept at least as high as the top of the copper, but it should never reach the zinc. There should always be some bluestone crystals in the bottom of the jar. After the battery has been started...
Page 4 - Fig. 7. or cloth may be used to rub them, so as to reach all points of the surface. Where a large quantity is to be amalgamated, the following will be found to be a good method:• Dissolve eight ounces of mercury in a mixture consisting of two pounds of hydrochloric and one pound of nitric acid; when the solution is complete, add three pounds more of hydrochloric acid.
Page 43 - It usually consists of a cylindrical knob of ivory or porcelain capable of moving loosely through a hole in a circular support of porcelain or wood, and which, when pressed, forces a platinum-tipped spring against a metal pin, and so makes electrical contact between the two parts of the interrupted...
Page 39 - Figure 148), is used. The induction coil consists of a cylindrical bobbin having a central iron core surrounded by a short inner or "primary" coil of stout wire, and by an outer "secondary" coil made up of many thousand turns of very fine wire, which is carefully insulated between its different parts.
Page 37 - strength" of a magnet is the "strength" of its poles. The " strength " of a magnet pole must be measured by the magnetic force which it exerts.
Page 13 - ... water. The zinc should be lifted out occasionally and the sulphate washed off. Keep a supply of mercury in the porous cell so as to have the zinc always well amalgamated.

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