Selimo Romeo Bottone

“ If we immerse a strip of ordinary commercial sheet zinc in dilute acid (say sulphuric acid 1 part by measure, water 16 parts by measure [4] ) , we shall find that the zinc is immediately acted on by the acid, being rapidly corroded and dissolved, while at the same time a quantity of bubbles of gas are seen to collect around, and finally to be evolved at the surface of the fluid in contact with the plate. Accompanying this chemical action, and varying in a degree proportionate to the intensity of the action of the acid on the zinc, we find a marked development of heat and electricity. ”

“ If, however, we now connect the two plates together by means of any conductor, say a copper wire, then the strain to which the carbon plate is subjected finds its exit along the wire and the zinc plate, which is continually losing its strain under the influence of the acid, being thus at a lower potential (electrical level, strain) than the carbon, can and does actually take in and pass on the electric vibrations. It is therefore evident that no true "current" can pass unless the two elements of a battery are connected up by a conductor. ”

“ An electric bell is an arrangement of a cylindrical soft iron core, or cores, surrounded by coils of insulated copper wire. On causing a current of electricity to flow round these coils, the iron becomes, for the time being, powerfully magnetic (see § 13) . A piece of soft iron (known as the armature) , supported by a spring, faces the magnet thus produced. This armature carries at its free extremity a rod with a bob, clapper or hammer, which strikes a bell, or gong, when the armature, under the influence of the pull of the magnet, is drawn towards it. ”

“ In the first place, it must be borne in mind that a cell or battery, when at work, is continually setting up electric undulations, somewhat in the same way that an organ pipe, when actuated by a pressure of air, sets up a continuous sound wave. ”

“ As the property which zinc possesses of causing the extrication of gas (under the above circumstances) has a considerable influence on the efficiency of a battery, it is well to understand thoroughly what chemical action takes place which gives rise to this evolution of gas.
§ 18. All acids may be conveniently regarded as being built up of two essential portions, viz.: firstly, a strongly electro-negative portion, which may either be a single body, such as chlorine, iodine, bromine, etc., or a compound radical, such as cyanogen; secondly, the strongly electro-positive body hydrogen. ”

“ It is found that if a body be moved before the poles of a magnet in such a direction as to cut the lines of force, electricity is excited in that body, and also around the magnet. The ordinary magneto-electric machines of the shops are illustrations of the application of this property of magnets. They consist essentially in a horse-shoe [Pg 15] magnet, in front of which is caused to rotate, by means of appropriate gearing, or wheel and band, an iron bobbin, or pair of bobbins, coiled with wire. ”

“ Whenever possible, the wiring of a house, etc., for bell work, should be done as soon as the walls are up and the roof is on. The shortest and straightest convenient route from bell to battery, etc., should always be chosen where practicable to facilitate drawing the wire through and to avoid the loss of current which the resistance of long lengths of wire inevitably entails. The wires should be run in light zinc tubes nailed to the wall. ”

“ It is better to rivet the platinum than to solder it, as the platinum is very apt to absorb the solder, in which case it rusts quickly, and the goodness of the contact is soon spoiled, when the bell ceases to ring. To rivet the platinum piece on to the spring, as shown at Fig. 26, it is only needful to procure a short length of No. 16 platinum wire, say 1⁄8 in., then, having drilled a corresponding hole at the desired spot in the contact spring, put the platinum wire half way through the hole, and give it one or two sharp blows on an anvil, with a smooth (pened) hammer. ”