Part 53 (1/2)

If a piece of zinc and copper joined by a wire be dipped in a liquid--generally weak sulphuric acid--which will act cheement is called a couple, or cell If many cells are connected, then it is called a battery

What is Thermo-electricity?

If two bars of any unlike ether at one end, and the other ends be connected by a wire and then the soldered end heated, a current will flow

What effects are produced by currents?

They produce heat, light, decomposition and combination in liquid chenetism, and in the animal body excite movements of thebattery produces heat in such a degree that all ht is produced in flashes, or if the end of the leading wires are connected with two pencils of hard carbon, and brought very near together, then a brilliant light, or arc, called the voltaic arc, is produced This is the dazzling bright light which we call electric light The che compound substances is called electrolysis In this ater can be decoen; copper sulphate into sulphur andadherent films of metal on the surface of any conductor; for if the article to be coated be attached to the negative electrode of a battery, and dipped into a solution of the metal hich we desire to coat the article, say copper or silver, and the positive electrode be attached to a plate of copper and also dipped into a liquid, when the current passes, the metal will be decomposed and deposited in a uniforative electrode This process is called _electro-plating_

What is Electrotyping?

It is the process of copying raved copper and steel plates, etc, by , from the ordinarybooks

Describe the process

The article to be copied is first covered with black-lead, and then a utta-percha This mould is placed in a solution of sulphate of copper, and attached to the negative pole of the battery, while a plate of copper is hung from the positive pole

The electric current decomposes the copper, which is deposited in a thin fil backed withand Stereotyping?

In stereotyping, a plaster of Paris mould is taken from the types, and upon this mould melted type-metal is poured, which, when hardened, makes a solid plate

Is there any other ?

Yes; that known as the paper process A uniforether sheets of thin, tough tissue paper The types are oiled, and the soft, moist sheet is placed on them and beaten doith a stiff brush until it receives an ih a press, and on being taken out the paper is found to form a perfect mould Into this mould the type-metal is poured and the plate fornetic effects of the current?

All conductors becoh thenet There are bodies which are natural nets Those which becoe of a current are called electro-nets?

They are ereat variety of electrical apparatus, principally in telegraphy

When was the first telegraph established?