CHAPTER XIX. MISCELLANEOUS EXPERIMENTS AND APPARATUS.

ELECTROLYSIS.

Liquid which will conduct a current of electricity is called an *electrolyte*. All electrolytes are compounds, that is, they consist of more than one substance. When an electric current passes through a liquid it decomposes it. This process of decomposition is called *electrolysis*.

Pure water is not a conductor of electricity. If sulphuric acid is added to water, the mixture become an electrolyte and will conduct. If an electric current is passed through water containing sulphuric acid, it will decompose the water.

Water is composed of oxygen and hydrogen and so bubbles of oxygen and hydrogen gas will rise from the liquid.

Figure 185 illustrates a very simple arrangement for decomposing acidulated water into oxygen and hydrogen gases.

It consists of a bottle with the bottom broken out, and provided with a cork fitted snugly into the neck. Two glass tubes pass through the cork. A small piece of platinum wire is sealed into the inside end of each glass tube. The platinum wires are connected to copper wires leading out of the lower ends of the tubes.

If the bottle is inverted and filled with a dilute solution of sulphuric acid, the current from two or three dry cells will decompose the water. The battery should be connected to the wires running through the glass tubes.

Bubbles of gas will rise from the platinum wires. Oxygen gas will rise from the positive wire or electrode and hydrogen gas from the negative electrode.

If two test tubes are filled with acidulated water and then inverted over the wires, the tubes will collect the gas. In a few minutes it will be noticed twice as much hydrogen as oxygen has been generated.

If copper or brass electrodes &re used the acid will attack the positive one and a chemical action will take place which will prevent the liberation of any appreciable amount of oxygen, unless an excessive amount of current is passed through.

ELECTROPLATING.

Electroplating consists of coating bodies with metal by means of an electric current.

The proper chemicals, a small tank and a suitable source of current are the only apparatus required. The process may be outlined as follows: Thoroughly clean the article to be electroplated so as to remove all grease and dirt. Attach it to the negative pole of the battery and suspend it in an electrolyte composed of some chemical salt of the metal to be deposited. In order to maintain the strength of the solution, a piece of metal of the kind to be deposited is attached to the positive electrode.

A tank for plating small articles such as keys, rings, knives, etc., may be made out of a square glass battery jar by providing it with a wooden moulding fitted around the top edge to support the conductor rods. The rods are made of brass or copper and are threaded at one end so as to be provided with binding posts. The centre rod is the one from which the articles to be plated are suspended. They should be attached to it by means of a thin copper wire. The two outside rods support the anodes. The anodes are sheets of metal of the kind to be deposited which, in the case of copper plating, would be copper, in a case of silver plating silver, nickel for nickel plating, etc.

Objects which are to be plated must be free from all traces of dirt or grease or the plating will not be uniform because it will not stick to the dirty spots.

Articles made of plaster, wax, etc., which are not conductors of electricity can be plated by first covering with powdered graphite. Articles of iron, steel, zinc and tin cannot be silver or gold plated unless first covered with a thin coating of copper.

A single storage cell is an excellent source of current for electroplating. A rheostat should be placed in the circuit so that the current can be regulated. The negative pole should be connected to the centre rod from which the articles are suspended. The positive pole is connected to the rods supporting the anodes.

The tank should be filled with electrolyte to within about an inch of the top. The articles to be plated and also the anodes should be completely submerged.

The electrolyte used for copper plating is simply a solution of copper sulphate in water. The electrolyte for nickel plating is composed of one part of nickel sulphate dissolved in twenty parts of water to which one part of sodium bisulphate is added.

Articles which have been electroplated must be buffed to give them a bright polish.

ELECTRIC CURRENT GENERATED BY HEAT.

If the point of contact between two dissimilar metals is heated, a current of electricity will be generated.

This principle was discovered nearly one hundred years ago by a scientist named Seebeck, and has resulted in many attempts on the part of inventors to utilize the heat of the sun’s rays in producing electricity.

An interesting experiment illustrating the production of electricity by heat can be easily performed with very simple apparatus. An alcohol lamp, candle or source of heat, a piece of copper, a steel needle and a galvanometer or a telephone receiver are all that are necessary.

The galvanometer or the telephone receiver, whichever is used, is for the purpose of detecting the electric current.

Connect the needle and the piece of copper, which should preferably be a small sheet, to the galvanometer or telephone receiver. Hold the copper sheet over the flame of the alcohol lamp until it is quite hot and then touch the hottest portion with the point of the needle. Enough current will be generated to produce a click In the telephone receiver or to cause the galvanometer needle to move. The needle should be pressed against the copper tightly enough so that the point cuts through the scale or oxide on the surface and makes a good electrical contact with the metal underneath.

Various devices for the production of electricity consisting of a large number of strips of dissimilar metals in contact with one another and arranged so that they can be easily heated have been invented. They are called "thermopiles."

A HANDY LIGHT.

Figure 188 shows a simple and handy form of light which utilizes the current from a home made primary cell. It consists of a glass fruit jar, fitted with a tight wooden top. A miniature porcelain socket and a 1.5 volt tungsten lamp are mounted on top.

The battery is arranged so that the zinc element can be drawn up out of the solution when the light is not in use and any waste thereby prevented. The zinc electrode consists of a strip of that metal fastened onto the lower end of a brass rod by means of two threaded nuts. The upper end of the rod passes through a small metal collar on the top of the cover, provided with a thumb-screw so that when the electrode is lifted up out of the solution it may be clamped firmly in that position.

The zinc strip should not be so long that it will not clear the solution when raised up if the jar is about half filled.

The positive electrode is a battery carbon mounted on the lower end of a brass rod. The brass rod in this case is not movable because the carbon can remain in the solution indefinitely without any waste.

The joint between the brass rods and the electrode should be coated with paraffine so that the chemicals in the solution will not cause any corrosion. The rods should be connected to the lamp socket. When the zinc is lowered into the solution, the lamp will be lighted by the current generated.

The electrolyte should be that described as the "bichromate" solution on page 34 of Vol. I of this book.

AN EXPERIMENTAL ARC LAMP.

An arc lamp is operated by causing an electric current to pass between two carbon rods. If the voltage is high enough, carbon vapor will form between the rods when they are separated a short distance. It requires an E. M. F. of approximately fifty volts to produce and maintain an arc.

A six volt storage battery will heat a pair of sharp pointed carbons to incandescence and produce a light somewhat similar to the electric arc.

Ordinary carbon rods such as those used in flashlight batteries will serve very nicely for a "battery arc lamp." The ends should be filed to sharp points. Figure 189 shows a simple method of mounting the carbons. The lower one is soldered to a piece of brass strip by taking advantage of the brass cap pressed over the upper end of flashlight battery carbons.

The upper carbon is mounted on the forward end of a brass lever which is pivoted near the back end so that an adjustable counterweight may be used to regulate the pressure on the point of contact between the two carbons.

If the carbons are touching lightly and are connected to a strong battery of six volts or more, the point of contact will be heated to incandescence and will produce a dazzling white light.

A real arc lamp for operation on the 110 volt current, in series with a bank of lamps, may be constructed on this same scheme by using larger carbons and eliminating the counterweight. The upper arm should be pivoted in the same manner but should move stiffly so that it will remain in any position in which it is set.

If the 110 volt current is used, the carbons should be brought together and then separated a short distance. The current will continue to flow across and will form an arc producing a very powerful purplish white light. The arc will consume the carbons quite rapidly and also generate a great deal of heat. Therefore if it is intended to use the light for any length of time it is advisable to fasten the carbons by means of a clamp so that they may be easily replaced.

A MAGNETIC DIVER.

This is a mystifying piece of apparatus to those who do not know its secret. The little diver apparently travels up and down from the bottom of a jar full of water to the surface at a word of command.

The diver consists of a small glass test tube about two inches long having the figure of a man painted upon it. The lower end is closed by a very small cork through which is pushed a large iron tack with the head on the outside. The test tube contains just enough water to float head up even with the surface of the water. The exact amount of water required to just permit enough buoyancy for the diver to rise again to the surface after he has been to the top will have to be determined by careful experiment.

The jar containing the diver should be set on a table having a drawer in which a pair of powerful electromagnets can be placed directly under the jar. The electro-magnets are connected to a strong battery and a switch located under the rug or carpet and so arranged that it may be closed by stepping on it lightly and without attracting attention. If the diver does not have too much bouyancy the attraction between the tack and the electro-magnets when the switch is closed should be sufficient to cause him to descend to the bottom of the jar. When the current is turned off the diver should rise again.

THE MAGNETIC FISH.

The same sort of a scheme employed in the Magnetic Diver may be used for producing a magnetic fish which will swim around and around a pan of water.

It consists of a small wooden fish having a magnetised sewing needle attached to the under side. The fish is placed in a bowl of water on a table having a drawer in which a pair of electro-magnets mounted on a rotating wooden arm may be placed so that they swing around directly underneath. A piece of strong twine wrapped around an empty spool and attached to the centre of the arm makes it possible to rotate the magnets by pulling on the string. When the magnets are connected to a battery they will exert a strong magnetic pull upon the needle fastened to the fish and if slowly rotated will cause the latter to follow slowly around the bowl.

A MAGNETIC CLOWN.

Small figures of men or animals cut out of sheet iron will perform many amusing acrobatic feats when under the influence of a magnet.

Such figures are easily cut out of an old tin cracker box with a pair of snips or strong shears. A realistic appearance may be secured with the aid of a little paint.

A tin clown having a sharply pointed hat, hands and feet will do all sorts of stunts when hanging from the poles of a horseshoe magnet. If several clowns are made they can be caused to hold hands, stand on each others heads, jump up in the air, etc.

AN ELECTRIC BREEZE.

If a sewing needle is connected to one of the discharge rods of a static machine and the point of the needle is presented to the flame of the candle while the machine is in operation, the flame will be repelled just as if a breeze or current of air were issuing from the needle. This is caused by the "brush" discharge which takes place whenever high voltage electricity has a chance to escape from a sharp point or edge. The brush discharge will be much more marked if the condensers or Leyden Jars are not connected to the discharge rods. The "electric breeze" can be felt if the point of the needle is brought near to the side of the face. It is necessary that the needle and the wire connecting it to the static machine be very carefully insulated from all surrounding objects which might dissipate the electricity before it has an opportunity to escape from the needle point.

A STATIC MOTOR.

This is a motor operated by the electricity from a static machine. It does not possess any appreciable amount of power and must be very carefully built and balanced in order to operate.

It consists of four celluloid "ping-pong" balls, B, B, B, B, covered with tinfoil and mounted on opposite ends of two wooden spokes. The balls should be at right angles to each other as shown in the illustration. The spokes pass through a cork. The cork is mounted on a wire spoke or knitting needle passing through its centre and supported in small notches in the top of two upright wooden bearings. The device must be very carefully balanced so that the slightest impulse will cause it to spin and so that there will not be any dead centre.

The upright bearings are mounted on a wooden base. Two other tinfoil covered balls A, A, are supported on glass or rubber insulating rods at opposite ends of the base on a level with the axle and in such a position that the balls B, B, B, B, almost touch A and A as they swing past.

Connect A and A each to one discharger rod on the Wimshurst machine. Start the machine and give the axle of the static motor a twist. As the balls B, B go past A and A they will receive a charge of electricity which will cause them to repel each other until they have swung past the other ball on the opposite side and discharge their electricity in return for a charge of the opposite sign.

Any of the Following

Practical Books

*will be sent At Once, Post-paid on receipt of price.*

_There is very little danger of losing currency in a letter if the following directions are observed:_

Cut a circular hole the diameter of

the coin in a piece of cardboard, of

sufficient size to fit closely in the

envelope. The cardboard should

be no thicker than the coin.

Insert the coin in the hole and paste

a piece of paper on both sides of

the cardboard to prevent the coin

from falling out.

COLE & MORGAN

Publishers of the Arts and Sciences Series

P.O. Box 473 New York, N. Y.

*The Boy Electrician*

Practical Plans for Electrical Toys and Apparatus, with an Explanation

of the Principles of Everyday Electricity.

*By ALFRED P. MORGAN.*

Author of "Wireless Telegraph Construction for Amateurs" and "Wireless

Telegraphy and Telephony," etc.

*With full-page Illustrations and 324 Working Drawings and Diagrams*

*by the author. 8vo., Cloth, Net Price, $2.00.*

This is the age of electricity. The most fascinating of all books for a boy must therefore be one dealing with the mystery of this ancient force and modern wonder, even a mere list of whose services is impossible. The best qualified of experts to instruct boys, Alfred P. Morgan, has in a book far superior to any other of its kind told not only how to make all kinds of motors, telegraphs, telephones, batteries, etc., and to do so economically, but has explained the principles upon which these depend for operation, and how the same thing is done in the every-day world be well presented and so attractive is this really great book that it will be an education for any bright boy to have it, as well as the best kind of a moral safeguard, by leaving no time or thought for evil, and a means of future benefit beyond the power of any one to reckon. Glancing over the pages of this book, one cannot but be impressed by the excellent illustrations, clearness of expression and the large number of subjects that are covered. It is beyond doubt the best book in this line that has ever been written or published. It is a book that will delight every boy who has a leaning towards electrical experiments. The author writes in a clear and chatty style and while he has a thorough technical knowledge of his subject he has succeeded in treating it in a simple manner so that it is readily intelligible to his young readers.

*Among the Chapter Headings and Contents are:*

Magnets and Magnetism—Static Electricity—Static Electric Machines—Cells and Batteries—Electro-Magnetism and Magnetic Induction—Electrical Units—Electrical Appurtenances—Electrical Measuring Instruments—Bells, Alarms and Annunciators—Electric Telegraphs—Microphones and Telephones—Induction Coils—Transformers—Wireless Telegraphy—Wireless Telephony—Electric Motors—Dynamos—An Electric Railway—Miniature Lighting—Miscellaneous Electrical Apparatus.

*READ WHAT HAS BEEN SAID OF IT.*

"Even a casual glance through the many pages of the book does not fail to emphasize the fact that Mr. Alfred P. Morgan has indeed succeeded well in giving the juvenile electricians a work that has long been sought."—Popular Electricity.

"We have no hesitation in commending the book to the attention of the juvenile audience for which it is intended."—Boston Post.

"A great book for enterprising boys. Bright boys will highly appreciate it and feel like thanking the wideawake publishers for putting such a reliable and interesting work in the field."—New Haven Journal.

"The book covers the subject of electricity thoroughly in all its phases and is a splendid acquisition to any boy’s library."—Detroit Times.

"In this age of electricity a book like the present one is both fascinating and valuable especially to boys. The book is attractive with its many illustrations and will prove of much educational value for any bright boy."—Zion’s Herald.

"This is an admirably complete and explicit handbook for young boys who fall under the spell of tinkering with electrical apparatus."—Boston Transcript.

"Well presented and attractive this book will be a source of great benefit and delight for any bright boy."—New Orleans Times-Picayune.

*Price, $2.00, Postpaid*

COUNTLESS OTHER MAGAZINES, NEWSPAPERS AND LIBRARIES HAVE

ENDORSED THIS GREAT BOOK. SEND FOR A COPY NOW.

*If you are interested in this great book, write for our 8-page special*

*descriptive circular.*

*Experimental Wireless Construction*

*EIGHTY-SIX PAGES NINETY-THREE ILLUSTRATIONS*

*Only 25 Cents, Postpaid*

Here at last is the book which every young experimenter interested in constructing his own wireless apparatus has been looking for.

A book which tells how to build apparatus which anyone would be proud to own. It is a more advanced book than "Wireless Construction and Installation for Beginners," and describes apparatus which is much more elaborate and sensitive. The instruments have all been the subject of considerable experimental work and study. All the apparatus has been put to practical test and carefully improved by clever experts. By purchasing this book you get the benefit of vast knowledge and experience and are enabled to build far better instruments than by following your own designs and haphazard methods.

THE TREMENDOUS POPULARITY OF THIS VALUABLE LITTLE BOOK IS ONLY AN INDICATION OF ITS GREAT WORTH.

It has only been on the market a short time, yet the sales will undoubtedly soon reach a point which would indicate that experimenters unquestionably consider, that in proportion to its size, it is the best book on the market.

It does not describe any old or obsolete forms of wireless apparatus but only the latest types of aerials, spark coils, keys, gaps, condensers, helixes, oscillation transformers, loose couplers, tuning coils, detectors, loading coils, variable condensers, aerial switches, etc.

IT IS ONE OF THE MOST DETAILED AND THOROUGH BOOKS EVER PUBLISHED.

The information is all intensely practical. Complete directions and dimensions are given. Nothing is left to be guessed at. The book must really be seen to be appreciated.

*Partial Contents*