This was written by Francis Crick, co-discoverer of DNA, about a year after they figured out it was a double-helix. In fact, in the article it’s still a bit of a hypothesis that DNA is a double-helix, they haven’t proved it yet.
The Structure of the Hereditary Material
An account of the investigations which have Led to the formulation of an understandable structure for DNA. The chemical reactions of this material within the nucleus govern the process of reproduction
by F. H. C. Crick
Viewed under a microscope, the process of mitosis, by which one cell divides and becomes two, is one of the most fascinating spectacles in the whole of biology. No one who watches the event unfold in speeded-up motion pictures can fail to be excited and awed. As a demonstration of the powers of dynamic organization possessed by living matter, the act of division is impressive enough, but even more stirring is the appearance of two identical sets of chromosomes where only one existed before. Here lies biology’s greatest challenge: How are these fundamental bodies duplicated? Unhappily the copying process is beyond the resolving power of microscopes, but much is being learned about it in other ways.
One approach is the study of the nature and behavior of whole living cells; another is the investigation of substances extracted from them. This article will discuss only the second approach, but both are indispensable if we are ever to solve the problem; indeed some of the most exciting results are being obtained by what might loosely be described as a combination of the two methods.
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If you are thinking of making this, keep in mind that 21 new elements have been discovered since it was printed. You can find out more at http://www.webelements.com/.
Building Blocks of Science
By HOWARD W. BLAKESLEE
Science Editor, The Associated Press
THE periodic table of the elements—the 96 metals, nonmetals and gases that form everything in the material universe— is the blueprint of the atomic future.
This table states a very simple fact: Everything material is made of three kinds of particles; namely, neutrons, protons and electrons. The difference between any two elements, iron and oxygen, for example, is in the number of particles.
On a map, specific places are always at specific points. The periodic table is like that. It tells facts about the elements that never change.
Although the table does not show where to look for uranium, it indicates the likely mineral formations. It shows that the kind of chain reaction that makes uranium bombs cannot be achieved without uranium’s aid. It also gives the limits of the uranium reaction and guarantees that it will not explode the earth.
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Firefly Chemistry
HOME-LABORATORY STUNTS WITH LUMINOUS SUBSTANCES
By Raymond B. Wailes
AMONG the most mysterious and beautiful of chemical experimerits are those producing substances that glow in the dark. With the aid of your home laboratory, you can make any number of common household products self-luminous. Coffee, tea, pepper, chili powder, mustard, cocoa, ginger, and many other groceries will produce a really visible light in a dark room, after you have treated them with the proper chemicals. You may even be able to make a flower from your garden emit enough illumination to allow you to read a few letters of print, and you will find that oil of bergamot, an ingredient of inexpensive perfumes, gives an especially strong glow.
All that you will need to produce these strange effects is a little grain or J denatured alcohol, a common alkali such as lye, hydrogen peroxide from the drug store, and one of the newer, “made with electricity” bleaching liquids and laundry whiteners. There are several of these liquids, widely advertised and obtainable at any grocery store. They are solutions of sodium hypochlorite, and you will find that this statement appears on the labels of the bottles.
Suppose you start in by purchasing about an ounce of oil of bergamot at the drug store. Add half a teaspoonful of it to an ounce of grain alcohol, rubbing alcohol, or radiator alcohol. Also dissolve in the liquid several pieces of solid sodium hydroxide (ordinary household lye will do), or potassium hydroxide. Now add about half a teaspoonful or so of drug-store hydrogen peroxide, and a like amount of the sodium hypochlorite solution. Darken the room, or take the mixture into a dark closet.
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Chemistry Spins a Yarn
By Kenneth M. Swezey
TRANSFORMATION of tree fibers or cotton linters into rayon fabrics is one of the greatest achievements of modern industrial chemistry. Chemically, rayon is almost pure cellulose, the same as cotton and linen. But instead of using cellulose as found in nature, the rayon chemist starts with cheap and plentiful spruce and hemlock trees, or the fuzz that clings to cotton seed after it has been ginned. He chops these up, dissolves them, and then causes the cellulose to reappear in silky filaments that may be spun, twisted, knit, or woven into forms that compete successfully with cotton, silk, linen, or wool.
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Mercury … THE LIQUID METAL
Important Alike to Science, Medicine, and Industry, This Fluid Element Is So Heavy That Iron Floats in It
By KENNETH M. SWEZEY
MERCURY, the only metal that is liquid at ordinary temperatures, solidifying at its freezing point of —39 deg. C, is one of the most fascinating elements. Because of its wide distribution and the simplicity of its metallurgy, it was known to the ancients. It was the principal substance the alchemists believed could be changed into gold and silver. Since then it has found wide use in medicine and in the arts.
Both the common term “quicksilver” and the Latin chemical name hydrargyrum, “water of silver,” eloquently describe the elusive liquid metal that does not wet glass and that is so heavy that iron nuts, bolts, and washers float in it like corks. Because of its weight, mercury is an ideal liquid for barometers and suction pumps. Its high boiling point (357 deg. C.) and even thermal expansion make it a fine fluid for thermometers. Although mercury actually can be changed into gold now by the miracle of atom smashing, the transmutation will never make anyone rich, for the cost far exceeds the value of the final product.
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Silver
. . . most useful precious metal, it is prized for coins, jewelry, plate, photography, and medicine.
By KENNETH M. SWEZEY
OF THE precious metals, gold, silver, and platinum, silver is both the most common and the most useful. Beauty, malleability, sonorousness, and resistance to atmospheric oxygen have put it in demand for coins, jewelry, tableware, ornaments, and bells since the beginning of history. Because it has the highest electric conductivity of any substance, it is prized in electric equipment. Silver nitrate, its most common salt, is used in making indelible ink and hair dyes, in photography and silver plating, and in medicine as an antiseptic and germicide taken both internally and externally.
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ZINC
From brazen helmet and warrior’s shield of the ancient world to the modern flashlight cell and galvan-ized steel plate, zinc has worked in the service of man.
By KENNETH M. SWEZEY
THOUGH it seldom makes headlines, humble zinc ranks with iron, copper, and lead as one of the most widely used metals in the world. Hundreds of thousands of tons of zinc are used annually as a molten dip to coat iron and steel pipes, tanks, and roofing for protection against corrosion. The process is known as galvanizing.
Brass is made of about 30 percent zinc and 70 percent copper. Granular zinc and zinc dust are used in the laboratory to release hydrogen from acids, to recover gold and silver from solutions, and in organic synthesis. More than 500,000,000 zinc cases for use in electrical dry cells are manufactured every year.
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UPDATE: Somone on digg pointed out that if you look closely at the picture of the father and son filling a model Zeppelin on page two you can see that it says “Hindenburg” on the side.
HOME EXPERIMENTS WITH HYDROGEN
by VERNON TRACEY
HYDROGEN, the lightest of chemical elements forms a very interesting field of experiment for the home chemist. It can be produced easily in several ways for experimental purposes; one of the most common of which consists of the action of sulphuric acid on zinc.
A flask into which is dropped a few grams of zinc scraps is fitted with a rubber stopper, thistle-tube and delivery-tube as shown in the photo. The thistle-tube is fitted into the stopper so the end will be about 1/8″ from the bottom of the flask. The end of the delivery-tube is near the top of the flask. Dilute sulphuric acid is poured down the thistle-funnel and hydrogen is produced when it comes in contact with the zinc. The top of the thistle-funnel is covered with a piece of glass to prevent the hydrogen from escaping. The hydrogen flows out through the delivery-tube and is collected in a bottle over the pneumatic trough.
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Table-Top Oil Refinery FOR THE HOME CHEMIST
By RAYMOND B. WAILES
Mechanized Armies Make Oil Supply Vital,” “Shortage of Fats Imperils Nation at War”—headlines like these spotlight what used to be routine items in a country’s shopping list, and give them new interest for home-laboratory experimenters.
Envious eyes the world over turn toward our vast forests of oil derricks, and the rivers of crude oil that refineries turn into gasoline for vehicles of war and peace. What makes their enormous production possible is the modern “cracking” process for extracting gasoline. Once the crude oil was simply distilled to separate, in turn, the gasoline and other substances it contained. Today, in addition, by-products of the distillation are “cracked” or broken down into gasoline, doubling the total yield.
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Tin
From the Bronze Age to World War II, this metal has been useful to man.
By KENNETH M. SWEZEY
WHEN you next speak of tin, be sure it’s with respect. For tin is not only one of the most useful of the common base metals, but it is by far also the most expensive. At a price of 52 cents a pound, this erroneously maligned metal is more than three times as costly as aluminum, is four times as dear as copper, and is 40 times as expensive as iron. What’s more, its important contribution to everyday living and to industry makes it worth the price.
Tin is one of the most ancient and honorable of metals. Alloyed with copper to make bronze, it has been used to fashion weapons, utensils, and tools since prehistoric time. In this alloy, tin makes the copper harder and more resistant to atmosphere and gives it a lower melting point. The tin mines of Cornwall, England, now supplying tin for the Allies’ war effort, have been in almost continuous operation since the Bronze Age.
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In the 1940’s practically every issue of Popular Science had a detailed chemistry article with experiments for teens to perform. I’m going to begin posting them in the new Chemistry category.
Learn About SULPHURIC ACID - No. 1 War Chemical
WARNING
NEVER pour water into concentrated sulphuric acid. They will boil and spatter over the room. This is caused by the acid’s great affinity for water. The only safe way is to pour the acid into the water, stirring constantly. Likewise, concentrated sulphuric acid will draw water out of the skin, leaving a dangerous burn.
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The basic message of the letter to all the readers of the magazine is: buy a Chemcraft outfit or your big brother will be killed by Japs and Nazis. Also, it will help you find a job after the war.
CHEMCRAFT
Dear Jack,
It was swell to get your V-mail letter. Hope it won’t be long before I am back home with you. I’m glad to hear that you are interested in my Chemcraft Outfit. Now I realize how important chemistry is and what a vital part it plays in our war effort. And after the war chemistry will be more important than ever. So the more you and I can learn about chemistry the better our future chances of success. Our Chemcraft Outfit will help you get a good start. So stick to it. All my love to you, Mom and Dad.
Your loving brother,
Dick
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