Magnesium the BANTAMWEIGHT METAL (Aug, 1946)

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Magnesium the BANTAMWEIGHT METAL

How Chemists Have Put It to Work as a Jack-of-All-Trades.

By KENNETH M. SWEZEY

DURING the war magnesium was extensively used as a lightweight structural metal for aircraft parts and as pyrotechnic material for star shells, signal flares, tracer bullets, and flash and incendiary bombs. Strong, silvery white, and only two thirds as heavy as aluminum, it is the lightest of all construction metals. In the form of powder, thin sheets, or wire, it burns with a dazzling flame that water or even carbon dioxide will not put out. Never found alone in nature, magnesium is made on a tremendous scale by the electrolysis of its compounds. These compounds are among the most plentiful substances in the crust of the earth. Whole mountain ranges consist of dolomite, a double carbonate of magnesium and calcium. Asbestos, talc, and meerschaum are magnesium silicates. Epsom salts, named after the springs at Epsom, England, where they were first isolated in 1695, are magnesium sulphate. In the form of its chloride, there are nearly 6,000,000 tons of magnesium in every cubic mile of-the sea, a vast storehouse of supply.

Less spectacular, perhaps, than the metal, the compounds of magnesium are just as important. Asbestos and magnesium oxide are among our most valuable insulators against heat. Magnesium oxychloride forms a superior artificial stone and flooring material. Magnesium carbonate is used for insulation and for making dentifrices, talcum powder, other magnesium chemicals, and Pyrex glass. Epsom, salts, citrate of magnesia, and milk of magnesia are three of the many magnesium compounds that are employed in medicine.

With only a box of Epsom salts as a starting material, you can make many of these compounds in your home laboratory. With a few inches of magnesium ribbon, you can likewise test some of the exciting properties of the metal itself.

One property that helps make the metal such an important incendiary material for wartime use is its ability to steal oxygen from such ordinarily stable compounds as water and carbon dioxide. During the war, magnesium fires generally were extinguished by smothering with sand. Water helped only when applied in quantities sufficient to cool the metal below the point of combustion. This was rarely possible.

As a demonstration of magnesium as an oxygen grabber, boil some water in a flask, and then with tongs lower a short length of lighted magnesium ribbon into the steam.

(Put away the rest of the ribbon before lighting the piece, and always handle with caution.) Instead of going out, the magnesium continues to burn brightly, getting oxygen by decomposing the steam.

Carbon dioxide, usually one of the best fire-extinguishing materials, is as helpless as steam against burning magnesium. Fill a beaker with this gas by pouring 1/2″ of water into it and adding a little baking soda (sodium bicarbonate) and vinegar or other common acid. As soon as the bubbling has stopped, test for carbon dioxide by lowering a lighted match into the beaker. The match will go out at once. Now lower a piece of burning magnesium into the glass and see the difference. The metal continues to burn furiously. In the process, it changes into magnesium oxide, and black specks of carbon, wrested from the carbon dioxide gas, are flung to the sides and bottom of the beaker.

Even nitrogen, which ordinarily is one of the most inert gases, will unite with hot magnesium when conditions are right, forming magnesium nitride. To show this, put a few short pieces of magnesium ribbon on the center of an upturned can cover and heat the cover over a gas flame until the metal catches fire. Then remove the cover from the flame and allow it to cool until you can touch it with your hand. Now put several drops of water on the warm substance that remains and hold a bit of cotton wool moistened with hydrochloric acid above it. White smoke of ammonium chloride immediately rises. On burning, the magnesium united with oxygen and nitrogen from the air, forming the oxide and nitride. When water was added, the nitride decomposed into ammonia gas and magnesium hydroxide.

Most magnesium compounds can be produced from the carbonate or the hydroxide. The carbonate occurs naturally as magnesite and, mixed with calcium carbonate, in certain forms of marble and limestone. It can be made artificially by mixing hot solutions of magnesium sulphate (Epsom salts) and sodium carbonate (washing soda). Since the carbonate is not soluble in water, it is precipitated as a fine white powder. When dried, it can be used as a polishing agent and for heat insulation.

Magnesium hydroxide also is made by precipitation. Again you can start with your Epsom salts, this time adding a solution of sodium hydroxide (ordinary lye). When dissolved, both of these solids produce clear solutions. Mixed together, they form a white precipitate. A suspension of this, in pure form, is the drug-store “milk of magnesia.” By strongly heating either your hydroxide or carbonate, you produce magnesium oxide (magnesia), used widely for heat insulating, for the lining of high-temperature furnaces, and for making oxychloride cement, widely used for flooring and imitative stone.

By dissolving either the carbonate or hydroxide in hydrochloric acid you get magnesium chloride, the compound found in sea water from which magnesium metal is made in vast quantities. To obtain crystals of this chemical, evaporate the solution over a water bath until nearly dry. Then complete the drying in a warm dry place in the open air.

If the heating is continued too long, the crystals will lose some of their water content and partly decompose, giving up hydrochloric acid.

This decomposition of magnesium chloride by heat provides one method for the manufacture of hydrochloric acid. As a demonstration, put some crystals of magnesium chloride in a test tube and fit the tube with a stopper having a glass delivery tube long enough to reach the bottom of a second test tube, which is half filled with water. Now gently heat the crystals. They will first melt, and then vapors will go through the delivery tube and bubble up through the water. Part will be water vapor and part hydrogen chloride. The latter will dissolve in the water, changing it into hydrochloric acid.

7 comments
  1. » Magnesium the BANTAMWEIGHT METAL says: May 21, 200712:28 pm

    [...] material for star shells, signal flares, tracer bullets, and flash and incendiary bombs source: Magnesium the BANTAMWEIGHT METAL, Modern [...]

  2. Elizabeth Bodtke says: November 15, 20074:40 am

    I stumbled upon this photo while searching for old cigarette ads from the early forties as my father was a Chesterfield model at that time. I was appalled to discover his photo here with the incredibly disrespectful title of Ronnie the Gay Riveter. The gentleman in your photograph, my dear father, served in the United States Navy for over 30 years as a Civil Engineer. He retired a Commander and worked with the Seebees in Vietnam. He also was in WWII, Korea and Vietnam. He is now buried at Arlington National Cemetary and died from mesothelioma cancer he got from exposure to asbestos while in the navy. I would appreciate your respectfully removing his photo from your blog. Thank you, Elizabeth Bodtke

  3. Warfie says: December 12, 20075:24 pm

    Well, I have nothing to do with this site, but, I am quite the fan, and to be honest, I don’t see what a Chesterfield Advert has to do with a Magnesium article… if you mean the next article, the Chesterfield Advert, well… I would be sorly disappointed if they removed the ad simply because someone was offended by a comment about it. The pages on this site are history, and when we start to ignore pieces of history because someone is offended, is when we start making the same mistakes all over again.

    They stopped teaching MacCarthyism and the Witch Hunts in schools, and look at the Patriot Act that’s been passed. A repeat of history.

    I personally enjoy all the old ads, and especially the older cigarette ads (I mean come on… Camel puts doctors through college backk in the day, just so the doctors would tout Camel Menthols as a belifit to your health… or the “doctor recomended ‘T-Zone’” in the old Camel ads)

    I’m a smoker, yes, but I don’t fool myself into thinking it’s a healthy habit… nor would I want to see such adverts from the past be deleted from our collective memory, simply because someone doesn’t like the advert as it’s presented today.

    Looking at the Chesterfield ad, and taking it into today’s context, there is nothing inappropriate about the commentary on it. Okay, the man in the ad is an American Hero, and your father, and the man fought in many wars… remember him for that, yes, and I do salute him for that… but, even though the picture in the ad may be a picture of him, I hardly think that the ad, or any comments about the ad, are a reflection upon him. Just like any other ad.

    Hell, I’ve seen ads, and billboards over the last few years talking about VD, and I know at least two of the people who have appeared in those ads, and know for a fact that they do not have VD… I’ve seen ads where the person as a parent, suggests a brand of detergent, or peanutbutter, and yet, I know for a fact that the person is neither married, nor a parent. Hell, Micheal Jackson’s deal with his Pepsi ads in the 80s, is that he never have to actually drink Pepsi, as he doesn’t drink soda at all… so I hardly see an image of one’s father in a cigarette ad, as being that person’s father. It’s just an image.

    But, what do I know? I’m just a guy who enjoys reading old magazines, and enjoys all the time, effort, and work that goes into a site like this. It can’t be easy to put up such a site, and yet, how many “thank yous” do the people who do this site get? Keep in mind, all this hard work and effort they do, they do for free as well. Just something to think about.

  4. bantamweight says: June 1, 20089:03 pm

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  5. jayessell says: December 2, 200812:17 pm

    Elisabeth, the meaning of some words has changed over the past decades.
    I’m sure everyone understands this ad is from an era when that word
    meant ‘happy’.

    (Charlie, I don’t see that ad. Did you cave?)

  6. Don says: December 2, 20083:28 pm

    It’s Charlie’s comment with “Gay Riveter” in it, not the ad, and I think it’s right to remove it.

  7. Charlie says: December 2, 200810:33 pm

    Jayessell: The post she’s referring to is below, she just commented on the wrong post. I’m not going to remove the comment, for a couple of reasons:
    1) I think it’s disingenuous to change my posts after the fact.
    2) I don’t delete user’s comments unless they are spam. If someone objects to what I say, they are more then welcome to give me crap about it. People insult me all the time on this site, that’s fine with me.
    3) Obviously in a staged advertisement for cigarettes of all things, my comment was not about the model but the image of the ad. I’m sure the models in all of the ridiculous ads we make fun of are nice people, that doesn’t mean we shouldn’t mock the ads.
    4) And finally, I thought my comment was pretty damn funny.

    http://blog.modernmecha…

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