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  Lionel Chem-Lab - Chapter 17

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NOTE:  This book was published in 1942 as a manual to accompany several Lionel Chemistry sets of the time.  While some of the experiments and activities here may be safely done as written, a number of them use chemicals and methods no longer considered safe.  In addition, much of the information contained in this book about chemistry and other subjects is outdated and some of it is inaccurate.  Therefore, this book is probably best appreciated for its historical value rather than as a source for current information and good experiments.  If you try anything here, please understand that you do so at your own risk.  See our Terms of Use.
Pages 198 - 200

CHAPTER XVII

THE PRECIOUS METALS

Gold, silver and platinum are commonly referred to as the precious metals. Gold is found in practically every part of the world, usually in veins with quartz, or in alluvial deposits. When found with quartz, it can be separated by quarrying, crushing and by treatment with mercury. In alluvial deposits it is extracted by the washing operation known as placer mining.

As it is one of the heaviest of the metals and not easily tarnished by exposure to the air, it is quite suitable for use in coins. It is exceedingly ductile and malleable. For example, gold not only can be beaten into extremely thin leaf but a single grain of gold can be drawn into a wire five hundred feet long.

SILVER

Silver is a heavy, soft, white metal, similar to gold in that it is very ductile and malleable.

Silver has often been called the metal that makes photography possible and about one hundred and fifty tons are used annually in making photographic supplies. It is also used in this country for making silver coins which contain 90% silver and 10% copper. Silverware or tableware when made of sterling silver contains 92% silver and 8% copper. Some silver is also used in the manufacture of mirrors and electrical devices. Many ornamental articles are made of cheaper metals plated with silver.

EXPERIMENT No. 480 How to Oxidize Silver 

(CL-11, CL-22, CL-33, CL-44, CL-55, CL-66, CL-77)

APPARATUS: Potassium nitrate, test tube, candle or alcohol lamp, bright silver coin. 

PROCEDURE: Put three measures of potassium nitrate in a test tube and heat until crystals melt. Drop the coin in the test tube. Reheat test tube for about a minute. Remove coin and note the formation of silver oxide.

EXPERIMENT No. 481 Silver Sulfide

(CL-44, CL-55, CL-66, CL-77)

APPARATUS: Sodium thiosulfate, alcohol lamp, bright silver coin,
 

198


LIONEL CHEM-LAB 199

gold dredging

U. S. Bureau Of Mines

This gold dredge with a fifteen cubic foot capacity is a far cry from the pans of the 19th century prospector.


test tube holder.

PROCEDURE: Put one measure of sodium thiosulfate on a silver coin. Hold coin with your test tube holder and heat carefully until the surface of the coin darkens. Rinse the coin.

SUMMARY: Heat causes the sodium thiosulfate to decompose liberating sulfur which combines with silver to form black silver sulfide.

EXPERIMENT No. 482 Preparation Of Silver Chloride

(CL-44, CL-55, CL-66, CL-77)

APPARATUS: Hydrochloric acid, silver coin and eye dropper.

PROCEDURE: Place a drop of hydrochloric acid on a silver coin. Set aside for one hour. After an hour, note the black stain which has formed.

SUMMARY: The silver coin is stained black because silver chloride, formed in the reaction between hydrochloric acid and silver, decomposes upon exposure to sunlight.

PLATINUM

Platinum, the third of our precious metals, is grayish-white and may be polished to a high luster. Like gold, it is found in alluvial deposits.

Because platinum is a very inactive element chemically and is not attacked by any of the common acids, the dentist and the chemist find platinum


200 PRECIOUS METALS

instruments and containers invaluable in their laboratories.

A good proportion of the demand for platinum is found in the jewelry business where its attractive appearance, its non-tarnishing features and its high cost make it desirable.


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