Electricity for Boys Part 14

The X-ray will pa.s.s through the water without being changed from a straight line. The foregoing being the case, it was but a simple step to conclude that if it were possible to find a means whereby the human eye could see within the ultra-violet beam, it would be possible to see through opaque substances.

From the discovery so important and far reaching it was not long until it was found that if the ultra-violet rays, thus propagated, were transmitted through certain substances, their rates of vibration would be brought down to the speeds which send forth the visible rays, and now the eye is able to see, in a measure at least, what the actinic rays show.

This discovery was but the forerunner of a still more important development, namely, the discovery of _radium_. The actual finding of the metal was preceded by the knowledge that certain minerals, and water, as well, possessed the property of radio-activity.

Radio-activity is a word used to express that quality in metals or other material by means of which obscure rays are emitted, that have the capacity of discharging electrified bodies, and the power to ionize gases, as well as to actually affect photograph plates.

Certain metals had this property to a remarkable degree, particularly uranium, thorium, polonium, actinium, and others, and in 1898 the Curies, husband and wife, French chemists, isolated an element, very ductile in its character, which was a white metal, and had a most brilliant l.u.s.ter.

Pitchblende, the base metal from which this was extracted, was discovered to be highly radio-active, and on making tests of the product taken from it, they were surprised to find that it emitted a form of energy that far exceeded in calculations any computations made on the basis of radio-activity in the metals. .h.i.therto examined.

But this was not the most remarkable part of the developments. The energy, whatever it was, had the power to change many other substances if brought into close proximity. It darkens the color of diamonds, quartz, mica, and gla.s.s. It changes some of the latter in color, some kinds being turned to brown and others into violet or purple tinges.

Radium has the capacity to redden the skin, and affect the flesh of persons, even at some considerable distance, and it is a most powerful germicide, destroying bacteria, and has been found also to produce some remarkable cures in diseases of a cancerous nature.

The remarkable similarity of the rays propagated by this substance, with the X-rays, lead many to believe that they are electrical in their character, and the whole scientific world is now striving to use this substance, as well as the more familiar light waves of the Roentgen tube, in the healing of diseases.

It is not at all remarkable that this use of it should first be considered, as it has been the history of the electrical developments, from the earliest times, that each successive stage should find advocates who would urge its virtues to heal the sick.

It was so when the dynamo was invented, when the high tension current was produced; and electrical therapeutics became a leading theme when transmission by induction became recognized as a scientific fact.

It is not many years since the X-rays were discovered, and the first announcement was concerning its wonderful healing powers.

This was particularly true in the case of radium, but for some reason, after the first tests, all experimenters were thwarted in their theories, because the science, like all others, required infinite patience and experience. It was discovered, in the case of the X-ray, that it must be used in a modified form, and accordingly, various modifications of the waves were introduced, called the _m_ and the _n_ rays, as well as many others, each having some peculiar qualification.

In time, no doubt, the investigators will find the right quality for each disease, and learn how to apply it. Thus, electricity, that most alluring thing which, in itself, cannot be seen, and is of such a character that it cannot even be defined in terms which will suit the exact scientific mind, is daily bringing new wonders for our investigation and use.

It is, indeed, a study which is so broad that it has no limitations, and a field which never will be exhausted.

THE END

GLOSSARY OF WORDS USED IN TEXT OF THIS VOLUME

Acid. Acc.u.mulator material is sulphuric acid, diluted with water.

Active That part of the material in acc.u.mulator plates Material. which is acted upon by the electric current.

Acc.u.mulator. A cell, generally known as a storage battery, which while it initially receives a charge of electricity, is nevertheless, of such a character, owing to the active material of which it is made, that it acc.u.mulates, or, as it were, generates electricity.

Aerial Wire, The wire which, in wireless telegraphy, is carried or Conductor. up into the air to connect the antennae with the receiving and sending apparatus.

Alarm, Burglar. A circulating system in a building, connected up with a bell or other signaling means.

Alloy. A mixture of two or more metals; as copper and zinc to make bra.s.s; nickel and zinc to form German silver.

Alternating Current. A current which goes back and forth in opposite directions, unlike a direct current which flows continuously in one direction over a wire.

Alternation. The term applied to a change in the direction of an alternating current, the frequency of the alternations ranging up to 20,000 or more vibrations per second.

Amber. A resin, yellow in color, which when rubbed with a cloth, becomes excited and gives forth negative electricity.

Ammeter. An instrument for measuring the quant.i.ty or flow of electricity.

Ampere. The unit of current; the term in which strength of the current is measured. An ampere is an electromotive force of one volt through a resistance of one ohm.

Annunciator. A device which indicates or signals a call given from some distant point.

Anode. The positive terminal in a conducting circuit, like the terminal of the carbon plate in a battery. It is a plate in an electroplating bath from which the current goes over to the cathode or negative plate or terminal.

Arc. A term employed to designate the gap, or the current which flows across between the conductors, like the s.p.a.ce between the two carbons of an arc lamp, which gives the light.

Armature. A body of iron, or other suitable metal, which is in the magnetic field of a magnet.

Armature Bar. The piece which holds the armature. Also one of a series of bars which form the conductors in armature windings.

Armature Coil. The winding around an armature, or around the core of an armature.

Armature Core. The part in a dynamo or motor which revolves, and on which the wire coils are wound.

Astatic (Galvanometer). That which has no magnetic action to direct or divert anything exterior to it.

Atom. The ultimate particle of an elementary substance.

Attraction. That property of matter which causes particles to adhere, or cohere, to each other. It is known under a variety of terms, such as gravitation, chemical affinity, electro-magnetism and dynamic attraction.

Automatic Cut-out. A device which acts through the operation of the mechanism with which it is connected. It is usually applied to a device which cuts out a current when it overcharges or overloads the wire.

Bath. In electroplating, the vessel or tank which holds the electroplating solution.

Battery. A combination of two or more cells.

Battery, Dry. A primary battery in which the electrolyte is made in a solid form.

Battery, Galvanic. A battery which is better known by the name of the Voltaic Pile, made up of zinc and copper plates which alternate, and with a layer of acidulated paper between each pair of plates.

Battery, Storage. A battery which acc.u.mulates electricity generated by a primary battery or a generator.

Brush. A term applied to the conducting medium that bears against the cylindrical surface of a commutator.

Buzzer. An electric call produced by a rapidly moving armature of an electro-magnet.

Cable. A number of wires or conductors a.s.sembled in one strand.

Candle-power. The amount of light given by the legal-standard candle. This standard is a sperm candle, which burns two grains a minute.