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authornfenwick <nfenwick@pglaf.org>2025-01-22 18:47:00 -0800
committernfenwick <nfenwick@pglaf.org>2025-01-22 18:47:00 -0800
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-
-<div style='text-align:center; font-size:1.2em; font-weight:bold'>The Project Gutenberg eBook of The Mysterious Box, by Bernard Keisch</div>
-
-<div style='display:block; margin:1em 0'>
-This eBook is for the use of anyone anywhere in the United States and
-most other parts of the world at no cost and with almost no restrictions
-whatsoever. You may copy it, give it away or re-use it under the terms
-of the Project Gutenberg License included with this eBook or online
-at <a href="https://www.gutenberg.org">www.gutenberg.org</a>. If you
-are not located in the United States, you will have to check the laws of the
-country where you are located before using this eBook.
-</div>
-
-<p style='display:block; margin-top:1em; margin-bottom:0; margin-left:2em; text-indent:-2em'>Title: The Mysterious Box</p>
-<p style='display:block; margin-top:0; margin-bottom:1em; margin-left:2em; text-indent:0;'>Nuclear Science and Art</p>
-
-<div style='display:block; margin-top:1em; margin-bottom:1em; margin-left:2em; text-indent:-2em'>Author: Bernard Keisch</div>
-
-<div style='display:block; margin:1em 0'>Release Date: August 18, 2021 [eBook #66082]</div>
-
-<div style='display:block; margin:1em 0'>Language: English</div>
-
-<div style='display:block; margin:1em 0'>Character set encoding: UTF-8</div>
-
-<div style='display:block; margin-left:2em; text-indent:-2em'>Produced by: Stephen Hutcheson and the Online Distributed Proofreading Team at https://www.pgdp.net</div>
-
-<div style='margin-top:2em; margin-bottom:4em'>*** START OF THE PROJECT GUTENBERG EBOOK THE MYSTERIOUS BOX ***</div>
-<div id="cover" class="img">
-<img id="coverpage" src="images/cover.jpg" alt="The Mysterious Box: Nuclear Science and Art" width="1000" height="1551" />
-</div>
-<div class="box">
-<h1>THE MYSTERIOUS BOX:
-<br />Nuclear Science and Art</h1>
-<p class="center"><span class="ss"><span class="rubric">by
-<br />Bernard Keisch</span></span></p>
-</div>
-<h2 id="toc" class="center">Contents</h2>
-<dl class="toc">
-<dt><a href="#c1">The Mysterious Box</a> 2</dt>
-<dt><a href="#c2">How Old Is a Painting?</a> 11</dt>
-<dt><a href="#c3">Who Was the Artist?</a> 24</dt>
-<dt><a href="#c4">Other New Tools for Art Authentication</a> 36</dt>
-<dt><a href="#c5">One Mystery Solved</a> 42</dt>
-<dt><a href="#c6">Reading List</a> 44</dt>
-</dl>
-<p class="center smaller">United States Atomic Energy Commission
-<br />Office of Information Services
-<br />Library of Congress Catalog Card Number: 70-606040
-<br />1970; 1974 (rev.)</p>
-<div class="pb" id="Page_i">i</div>
-<h3>The Author</h3>
-<div class="img">
-<img src="images/p01.jpg" id="ncfig1" alt="Bernard Keisch" width="652" height="800" />
-</div>
-<p>Dr. Bernard Keisch received his B.S. degree from Rensselaer
-Polytechnic Institute and his Ph.D. from Washington University.
-He is a Senior Fellow with the Division of Sponsored
-Research of Carnegie-Mellon University in Pittsburgh. He is
-presently engaged in a project that deals with the applications
-of nuclear technology to art identification. This is jointly
-sponsored by the U. S. Atomic Energy Commission and the
-National Gallery of Art. Previously he was a nuclear research
-chemist with the Phillips Petroleum Company and senior
-scientist at the Nuclear Science and Engineering Corporation.
-He has contributed articles on art authentication to a number
-of journals. For the AEC, in addition to this booklet, he has
-written <i>The Atomic Fingerprint: Neutron Activation Analysis</i>,
-<i>Secrets of the Past: Nuclear Energy Applications in Art
-and Archaeology</i>, and <i>Lost Worlds: Nuclear Science and
-Archaeology</i>.</p>
-<div class="pb" id="Page_ii">ii</div>
-<div class="box">
-<p>Nuclear energy is playing a vital role in
-the life of every man, woman, and child in the
-United States today. In the years ahead it will
-affect increasingly all the peoples of the earth.
-It is essential that all Americans gain an
-understanding of this vital force if they are to
-discharge thoughtfully their responsibilities as
-citizens and if they are to realize fully the
-myriad benefits that nuclear energy offers
-them.</p>
-<p>The United States Atomic Energy Commission
-provides this booklet to help you
-achieve such understanding.</p>
-</div>
-<div class="box">
-<h3><a href="#cover">The Cover</a></h3>
-<p>This painting, originally believed to be the
-work of the Dutch artist Frans Hals
-(1580-1666), is a fake. Measurements of the
-naturally radioactive isotopes, polonium-210
-and radium-226, in lead white from the paint
-proved that it was no more than 50 years old.</p>
-</div>
-<div class="pb" id="Page_1">1</div>
-<div class="img" id="fig1">
-<img src="images/p02.jpg" alt="" width="758" height="1199" />
-<p class="pcap"><i>A Van Meegeren forgery of a Vermeer.</i></p>
-</div>
-<div class="pb" id="Page_2">2</div>
-<h2 id="c1"><span class="small">The Mysterious Box</span></h2>
-<p>The New Jersey sun was high overhead
-and the day was hot. The three boys walking
-along a deserted stretch of beach didn&rsquo;t mind
-because they were barefoot and in their
-swimsuits. Occasionally they would dash in
-and out of the surf to cool off.</p>
-<p>Suddenly Martin let out a yell as his toe
-hit something hard hidden in the sand at the
-water&rsquo;s edge. A moment later Bill and Harley
-were helping Martin dig out a large wooden
-case. It was heavy, well built, tightly sealed,
-and had foreign words written on it.</p>
-<p>&ldquo;Maybe it&rsquo;s a pirate treasure chest,&rdquo; said
-Martin, who was almost eight and had just
-read <i>Treasure Island</i> for the first time the
-week before.</p>
-<p>&ldquo;You&rsquo;re crazy,&rdquo; said Harley, who, nearly
-ten, was much older and wiser.</p>
-<p>Bill, going on twelve, thought aloud, &ldquo;It
-must be something worthwhile; maybe we can
-sell it and buy those model rockets we
-wanted.&rdquo;</p>
-<p>The three boys soon found that they
-couldn&rsquo;t open the box and that it was too
-heavy to drag along the sand easily.</p>
-<p>&ldquo;Martin,&rdquo; said Bill, &ldquo;get Dad while Harley
-and I stand guard.&rdquo;</p>
-<p>Two hours later the box was at their
-house and everyone in the family was trying
-to read what was written on it. About all that
-was readable was a large &ldquo;U&rdquo; followed
-by what appeared to be two numbers. Some
-<span class="pb" id="Page_3">3</span>
-of the other marks looked like old German
-script and there was a date, 1945.</p>
-<p>&ldquo;You know,&rdquo; said Bill, &ldquo;I bet that came
-from a World War II German submarine that
-our Coast Guard or Navy sank.&rdquo;</p>
-<p>&ldquo;Let&rsquo;s open it up!&rdquo; said Harley as Martin
-ran to get the screwdrivers.</p>
-<p>Inside they found a thoroughly waxed
-carton that they had to cut open. Everyone
-held their breath as their father lifted the top.</p>
-<p>&ldquo;Nothing but a bunch of pictures,&rdquo; said
-Martin who was still hoping for pirate treasure.</p>
-<p>&ldquo;Paintings can be worth a lot of money,&rdquo;
-said Dad, &ldquo;thousands or even millions of
-dollars.&rdquo;</p>
-<p>&ldquo;Well then we&rsquo;re rich!&rdquo; yelled Harley and
-Bill together.</p>
-<p>&ldquo;Not so fast,&rdquo; said Dad. &ldquo;First of all, we
-don&rsquo;t know if the paintings are really valuable.
-Also, it looks like these might be part of
-the art treasures that the Nazis stole from the
-countries they conquered in World War II.
-Maybe someone was trying to get them by
-submarine to a neutral country, like Argentina,
-just before the end of the war, and the
-sub was sunk. If they are real and stolen,
-they&rsquo;ll have to go back to their rightful
-owners. But cheer up, maybe there&rsquo;s a reward.&rdquo;</p>
-<p>&ldquo;How do we collect it?&rdquo; asked Bill. &ldquo;If
-the Nazis grabbed them, aren&rsquo;t they real for
-sure?&rdquo;</p>
-<p>&ldquo;Not necessarily,&rdquo; Dad continued. &ldquo;The
-Nazis were fooled sometimes by people who
-sold them fakes. There was one painting that
-<span class="pb" id="Page_4">4</span>
-Hitler&rsquo;s sidekick, G&ouml;ring, bought that was
-supposed to be a 17th century painting by
-Vermeer, a Dutch painter. Because Vermeer&rsquo;s
-work is so valuable, it&rsquo;s usually impossible to
-buy one for any amount of money.</p>
-<p>&ldquo;Vermeer is regarded as a national hero
-by the Dutch. The matter was investigated
-and the painting traced to Han Van
-Meegeren, a modern Dutch painter who had
-only a fair talent. When Van Meegeren realized
-he might be charged with treason by the
-Dutch for selling a Vermeer to the Nazis, he
-confessed that he had painted it himself. He
-also confessed that he had painted other
-forgeries that fooled some of the experts and
-were sold for a lot of money.</p>
-<p>&ldquo;Many people, however, thought Van
-Meegeren was only lying to save himself from
-the charge of treason, and the whole thing
-had to be decided by a committee of scientific
-art experts appointed by a court of law.
-Using the methods that were then available,
-the experts showed that Van Meegeren had
-done a remarkable job of forgery and they
-were convinced that he had been telling the
-truth about painting those pictures.</p>
-<p>&ldquo;At the time, the important ways the
-experts used to examine a painting included
-studying the work with X rays, which could
-show another painting underneath, analyzing
-the pigments (or coloring materials) used in
-the paint, and examining the painting for
-certain signs of old age.</p>
-<div class="pb" id="Page_5">5</div>
-<div class="img" id="fig2">
-<img src="images/p03.jpg" alt="" width="621" height="999" />
-<p class="pcap"><i>Han Van Meegeren listens to the evidence at his trial
-in Amsterdam. In the background is &ldquo;The Blessing of
-Jacob&rdquo;, which was sold in 1942 as the work of
-Vermeer.</i></p>
-</div>
-<div class="pb" id="Page_6">6</div>
-<div class="img" id="fig3">
-<img src="images/p04.jpg" alt="" width="800" height="914" />
-<p class="pcap"><i>An authentic Pieter de Hooch work, &ldquo;The Card Players&rdquo;, painted in the
-17th century.</i></p>
-</div>
-<div class="pb" id="Page_7">7</div>
-<div class="img" id="fig4">
-<img src="images/p04a.jpg" alt="" width="800" height="922" />
-<p class="pcap"><i>A forgery of a Pieter de Hooch picture painted in the 20th century by
-Han Van Meegeren.</i></p>
-</div>
-<div class="pb" id="Page_8">8</div>
-<div class="img" id="fig5">
-<img src="images/p05.jpg" alt="" width="455" height="600" />
-<p class="pcap"><i>&ldquo;Head of Christ&rdquo; by Van
-Meegeren.</i></p>
-</div>
-<p>&ldquo;Van Meegeren was well acquainted with
-these methods. He scraped the paint from old
-paintings that weren&rsquo;t worth much just to get
-the canvas and tried to use pigments that
-Vermeer would have used. He knew that old
-paint was very, very hard and impossible to
-dissolve; so he cleverly mixed a chemical
-(phenolformaldehyde) into his paint, and this
-hardened into Bakelite when he heated the
-finished painting in an oven.</p>
-<p>&ldquo;For some of the paintings, Van Meegeren
-became careless and the experts did find
-traces of a modern pigment (cobalt blue) in
-the paint. They also found the Bakelite. For
-one or more paintings, Van Meegeren did so
-well that, in spite of all this evidence, a few
-people still weren&rsquo;t convinced that these
-paintings were painted by Van Meegeren and
-not by Vermeer.&rdquo;</p>
-<p>Bill, who by this time was bursting with
-questions, interrupted, &ldquo;You mean they still
-aren&rsquo;t sure about some of those paintings
-after 25 years? Aren&rsquo;t there better ways of
-telling whether a painting is genuine or not?
-You&rsquo;re a scientist. Can&rsquo;t scientists like you do
-something about it now?&rdquo;</p>
-<p>&ldquo;Yes, recently a method was developed to
-settle just such a question. It&rsquo;s based on
-measurements of natural radioactivity in one
-pigment that all artists used hundreds of years
-ago. And the method was applied to some of
-the Van Meegeren paintings including the best
-one of them all.&rdquo;</p>
-<p>&ldquo;How did it come out?&rdquo; asked Martin.</p>
-<div class="pb" id="Page_9">9</div>
-<div class="img" id="fig6">
-<img src="images/p05b.jpg" alt="" width="622" height="800" />
-<p class="pcap"><i>An X ray of part of the Van Meegeren forgery, &ldquo;Christ and His
-Disciples at Emmaus&rdquo;. In the
-white circle are traces of paint from the original painting that Van
-Meegeren scraped off to obtain the old canvas. When the painting was
-believed to be a genuine Vermeer, it was sold for about $300,000.</i></p>
-</div>
-<div class="img" id="fig7">
-<img src="images/p05d.jpg" alt="" width="800" height="706" />
-<p class="pcap">The complete painting.</p>
-</div>
-<div class="pb" id="Page_10">10</div>
-<div class="img" id="fig8">
-<img src="images/p06.jpg" alt="" width="800" height="930" />
-<p class="pcap"><i>A Van Meegeren forgery of a Vermeer.</i></p>
-</div>
-<p>&ldquo;How does it work?&rdquo; asked Harley.</p>
-<p>&ldquo;You mean paintings are radioactive?&rdquo;
-exclaimed Bill.</p>
-<p>&ldquo;Can we do it to the paintings we
-found?&rdquo; asked all three together.</p>
-<div class="pb" id="Page_11">11</div>
-<h2 id="c2"><span class="small">How Old Is a Painting?</span></h2>
-<p>&ldquo;One question at a time. I&rsquo;ll tell you how
-the method works and what it does if you&rsquo;re
-really interested.&rdquo;</p>
-<p>&ldquo;We&rsquo;re interested! We&rsquo;re interested!&rdquo;
-chorused the boys.</p>
-<p>&ldquo;In the first place, this method works
-only in certain cases of suspected forgery.
-Over the last 50 or 100 years, a number of
-paintings have turned up that seemed, even
-to the best art experts, to be several hundred
-years old. Some of these were genuine, and
-some were painted by forgers who could not
-resist the high prices paid for works of art. The
-National Gallery of Art, in Washington, D. C.,
-thinking that there might be a way of
-detecting these forgeries, gave its support to a
-group of scientists who developed a method
-for this purpose.</p>
-<p>&ldquo;To understand how the method works,
-you need to know a little about how radioactive
-atoms disintegrate to form atoms of
-other elements. In this case we are interested
-in the natural radioactivity that occurs in
-certain rocks. As a matter of fact, in almost
-all rocks in the earth&rsquo;s crust there is a certain
-small quantity of uranium.&rdquo;</p>
-<p>&ldquo;I thought uranium was rare,&rdquo; interrupted
-Bill.</p>
-<p>&ldquo;It is, but we&rsquo;re talking about such small
-quantities that its difficult for scientists using
-the most sensitive equipment to detect it. The
-uranium in the rock decays to another radioactive
-element and that one decays to
-another, and another, and another, and so
-<span class="pb" id="Page_12">12</span>
-forth, in a series of elements that results in
-lead, which is not radioactive. In this series
-are two radioactive elements, radium and a
-radioactive isotope of lead, that help us to
-date paintings. To understand this, we must
-first understand how radioactive elements
-decay.</p>
-<p>&ldquo;All radioactive elements have what is
-known as a &lsquo;half-life&rsquo;; that is, in a certain
-period of time, half of the element disintegrates
-to another form. In another equal
-period of time, half of what is left
-disintegrates, and then half again, and so on.
-In the case of the uranium, which starts the
-series I am describing, the half-life is over
-4,000,000,000 years. Because of its long
-half-life there is plenty of uranium around
-and will be for a long, long time. On the other
-hand, radium, which I mentioned a moment
-ago, has a half-life of only 1600 years. In
-1600 years, half of it would be gone, and in
-another 1600 years half of that would be
-gone, and so on.</p>
-<p>&ldquo;The radioactive lead that we&rsquo;re interested
-in has a half-life of only 22 years. This
-means that if you start with a small quantity
-of this radioactive isotope of lead, which is
-called lead-210,<a class="fn" id="fr_1" href="#fn_1">[1]</a> then in only a few hundred
-years it would have disappeared. However, in
-rock, where there is uranium, the uranium
-keeps feeding the elements following it in the
-series, so that as fast as they decay they are
-reproduced by the element before them.&rdquo;</p>
-<div class="pb" id="Page_13">13</div>
-<div class="img" id="fig9">
-<img src="images/p07.jpg" alt="" width="1200" height="755" />
-<p class="pcap"><i>The Uranium Series. In this simplified diagram, the
-double vertical arrows represent alpha radioactivity
-and the single slanted arrows represent
-beta radioactivity. The times shown on the arrows
-are the half-lives for each step.</i></p>
-</div>
-<dl class="undent pcap"><dt>Uranium-238</dt>
-<dd class="t">&dArr;<sup>&alpha;</sup><span class="hst">4&frac12; billion years</span></dd>
-<dt>Thorium-234</dt>
-<dd class="t">&darr;<sup>&beta;</sup><span class="hst">24 days</span></dd>
-<dt>Protoactimum-234</dt>
-<dd class="t">&darr;<sup>&beta;</sup><span class="hst">1&#8533; minutes</span></dd>
-<dt>Uranium-234</dt>
-<dd class="t">&dArr;<sup>&alpha;</sup><span class="hst">&frac14; million years</span></dd>
-<dt>Thorium-230</dt>
-<dd class="t">&dArr;<sup>&alpha;</sup><span class="hst">80 thousand years</span></dd>
-<dt>Radium-226</dt>
-<dd class="t">&dArr;<sup>&alpha;</sup><span class="hst">1600 years</span></dd>
-<dt>Radon-222</dt>
-<dd class="t">&dArr;<sup>&alpha;</sup><span class="hst">3&#8536; days</span></dd>
-<dt>Polonium-218</dt>
-<dd class="t">&dArr;<sup>&alpha;</sup><span class="hst">3 minutes</span></dd>
-<dt>Lead-214</dt>
-<dd class="t">&darr;<sup>&beta;</sup><span class="hst">27 minutes</span></dd>
-<dt>Bismuth-214</dt>
-<dd class="t">&darr;<sup>&beta;</sup><span class="hst">20 minutes</span></dd>
-<dt>Polonium-214</dt>
-<dd class="t">&dArr;<sup>&alpha;</sup><span class="hst">less than one second</span></dd>
-<dt>Lead-210</dt>
-<dd class="t">&darr;<sup>&beta;</sup><span class="hst">22 years</span></dd>
-<dt>Bismuth-210</dt>
-<dd class="t">&darr;<sup>&beta;</sup><span class="hst">5 days</span></dd>
-<dt>Polonium-210</dt>
-<dd class="t">&dArr;<sup>&alpha;</sup><span class="hst">138 days</span></dd>
-<dt>Lead-206</dt>
-<dd class="t">(Not Radioactive)</dd></dl>
-<div class="pb" id="Page_14">14</div>
-<p>&ldquo;I don&rsquo;t quite understand how that
-works,&rdquo; said Harley. &ldquo;What do you mean &lsquo;it
-keeps feeding it&rsquo;?&rdquo;</p>
-<p>&ldquo;Well, think of a series of lakes connected
-by waterfalls. At the top, the highest lake has
-an enormous supply of water. Following the
-waterfall coming out of the lake you find a
-smaller lake and then maybe a medium-sized
-lake, and after another waterfall, a smaller
-lake, then a tiny lake, and so on.</p>
-<p>&ldquo;As long as that big lake on top is full or
-nearly full, all the other lakes, whether they
-are small or medium-sized, will still be getting
-water as fast as it pours out. But if you cut
-off the supply of water from the upper lake
-to the next lake, then the smaller lakes will in
-time run dry. The same thing works with the
-radioactivity. In this series headed by uranium,
-as long as uranium is present all the
-other elements below it are kept supplied so
-that they don&rsquo;t run out.&rdquo;</p>
-<p>&ldquo;I understand that,&rdquo; said Bill, &ldquo;but how
-do we use that to date a painting?&rdquo;</p>
-<p>&ldquo;One of the pigments used by artists for
-over 2000 years is known as lead white and it
-is made from lead metal. The lead metal in
-turn is extracted from a rock called lead ore,
-in a process called smelting. The radioactive
-lead, this lead-210 that I mentioned, behaves
-like ordinary lead metal and goes along with
-it.</p>
-<p>&ldquo;The radium, which has a fairly long
-half-life, doesn&rsquo;t follow the lead metal, but is
-removed with other waste products in a
-material called slag. Since the longer-lived
-ancestor of the lead-210 is removed, the
-<span class="pb" id="Page_15">15</span>
-supply of lead-210 is cut off. (Or we can say
-that one of the waterfalls is shut off.) The
-lead-210 will then decay with its 22-year
-half-life.&rdquo;</p>
-<div class="img" id="fig10">
-<img src="images/p08.jpg" alt="" width="800" height="587" />
-<p class="pcap"><i>The radioactive series that starts with uranium is like a series of lakes
-connected by waterfalls. As long as uranium, the big one on top, has
-water in it, the others will be full and the falls will keep flowing. But
-when the first waterfall is shut off, the small lakes below it will run dry.</i></p>
-</div>
-<p>&ldquo;I get it,&rdquo; said Bill. &ldquo;That means that
-when you take a sample of old lead white
-paint, there shouldn&rsquo;t be any radioactive
-lead-210 left.&rdquo;</p>
-<p>&ldquo;That&rsquo;s right. But that would only be true
-if you removed all the radium. Actually, in
-the smelting process it&rsquo;s more usual to remove
-only 90 or 95% of the radium. In that case,
-the lead-210 would decay only until the
-amount left would be equal to the small
-amount of radium that wasn&rsquo;t removed. In
-<span class="pb" id="Page_16">16</span>
-effect, this would be like shutting off only
-part of the waterfall.&rdquo;</p>
-<p>&ldquo;So what do you find,&rdquo; asked Harley, &ldquo;if
-you measure the radioactivity in a sample of
-lead white paint?&rdquo;</p>
-<p>&ldquo;We find that if the paint is old, compared
-to the 22-year half-life of the lead, let&rsquo;s
-say 100 years old or more, then the amount
-of radioactivity from the lead-210 in the
-sample of paint will be equal to the amount
-of radioactivity from the radium in the
-sample. But if the paint is modern, let&rsquo;s say
-only 20 years old or so, then the amount of
-radioactivity from the lead-210 will be greater
-than the amount of radioactivity from the
-radium.&rdquo;</p>
-<p>Martin, who had been quiet through all
-this explanation, finally spoke up. &ldquo;Well, was
-it finally tried out? How did it work?&rdquo;</p>
-<p>&ldquo;Hundreds of samples were analyzed.
-These samples were taken from paintings of
-all ages, from some over 300 years old right up
-to others only a couple of years old. The old
-samples always showed equal amounts of
-radioactivity from lead-210 and radium while
-the modern ones always showed larger
-amounts of radioactivity from lead-210 than
-from radium. That meant that scientists had a
-way of definitely telling if a lead white paint
-was modern or not.</p>
-<p>&ldquo;Eventually, the method was tried on a
-number of paintings believed to be by Van
-Meegeren. Sure enough, every one of them
-showed that the paint couldn&rsquo;t possibly have
-been more than 30 or 40 years old and that
-Van Meegeren probably was telling the truth
-<span class="pb" id="Page_17">17</span>
-when he said that he had painted them. The
-paintings certainly were not genuine Vermeers
-from the 17th century.&rdquo;</p>
-<p>&ldquo;Okay, Dad,&rdquo; said Martin, &ldquo;can we use
-the method on any of the paintings we
-found? Are any of these paintings supposed
-to be old enough so that we can use this
-test?&rdquo;</p>
-<p>&ldquo;Not so fast. To find that out we have to
-do a lot of checking first.&rdquo;</p>
-<p>&ldquo;How do we go about it?&rdquo; asked Bill.</p>
-<p>&ldquo;Let&rsquo;s see now. There are nine paintings
-in the box you found. The first thing we
-should do is take them down to a museum or
-gallery and let the art experts look at them.
-Since we have a few weeks of vacation time
-left, what do you say we take a trip down to
-Washington, D. C., and show them to some
-experts at the National Gallery of Art?&rdquo;</p>
-<p>Over the next few weeks quite a few
-things happened to the boys and their paintings.
-Three of them were discarded right away
-because they were immediately recognized as
-being copies of no value. Two were relatively
-modern paintings with the signature Alfred
-Sisley; if genuine, they were less than 100
-years old. The remaining four appeared to be
-very old paintings. Two of them seemed to
-correspond to paintings that disappeared during
-the Second World War. Photographs and X
-rays were taken and sent to the museum in
-Holland, which had owned the missing pictures,
-so that they could make a preliminary
-examination.</p>
-<div class="pb" id="Page_18">18</div>
-<div class="img">
-<img src="images/p09.jpg" id="ncfig2" alt="uncaptioned" width="800" height="1023" />
-</div>
-<dl class="undent pcap"><dt>Radioactivity of Lead-210</dt></dl>
-<p class="pcapc">Lead-210 decaying with a half-life
-of 22 years. When no radium is present
-there is almost none left after 6 half-lives
-or 132 years.</p>
-<dl class="undent pcap"><dt>Radioactivity of Radium-226</dt></dl>
-<p class="pcapc">Over the same period of time, a small amount of radium
-decays very little because its half-life is about 1600 years.</p>
-<dl class="undent pcap"><dt>Radioactivity of Radium 226</dt>
-<dt>Radioactivity of Lead-210</dt></dl>
-<p class="pcapc">But when lead-210 decays in the presence
-of radium-226, the radioactivity of the lead-210
-only decreases until it is equal to the radioactivity
-of the radium.</p>
-<p>That left two that could have been old
-but whose origins were unknown. A series of
-simple chemical tests were begun on these and
-the boys watched experts take very small
-samples of paint for examination under the
-microscope. After several months a list of the
-pigments present in the paintings was prepared.
-All the pigments found were typical of
-old paintings and the ordinary examinations
-and tests couldn&rsquo;t prove whether the works
-were old or not. Finally, it was decided that
-<span class="pb" id="Page_19">19</span>
-the only way to tell if these paintings were
-truly old was to apply the test that Dad had
-described to the boys.</p>
-<p>The boys watched a painting restorer
-remove samples of nearly white paint right at
-the edge of the paintings. He worked carefully,
-using a very sharp scalpel and a stereo-binocular
-microscope, through which objects
-appeared to be sixty times larger than they
-really were. The sample of paint weighed
-approximately twenty-thousandths of a gram.
-The boys and their father took the samples to
-a radiochemical laboratory where they
-watched a radiochemist do the required analysis
-for lead-210 and radium in the samples.</p>
-<p>First the chemist dissolved the paint in
-acetic acid. This removed the lead white from
-the oil and from the small amounts of other
-pigments in the paint. The solutions were
-then heated and stirred with a silver disc
-hanging in the liquid. After several hours the
-disc still looked clean, but the chemist said
-that a radioactive element, polonium-210, was
-now plated onto the silver. Polonium-210 is a
-member of the uranium series following the
-lead-210, and a measurement of its radioactivity
-would be an accurate measurement of
-the radioactivity of lead-210.</p>
-<p>The silver discs prepared from the two
-samples were each placed in an instrument
-called an alpha-particle spectrometer. This
-instrument is extremely sensitive and can
-measure the very small amounts of polonium-210
-prepared from the tiny sample of paint
-that they started with.</p>
-<div class="pb" id="Page_20">20</div>
-<p>While the instruments were making the
-measurements, which took a couple of days,
-the chemist turned to the remaining solutions
-and began the analyses for radium.</p>
-<div class="img" id="fig11">
-<img src="images/p10.jpg" alt="" width="677" height="800" />
-<p class="pcap"><i>A painting being sampled under a stereo-binocular microscope.</i></p>
-</div>
-<div class="img" id="fig12">
-<img src="images/p10a.jpg" alt="" width="500" height="441" />
-<p class="pcap"><i>Lead white weighing
-twenty-thousandths of a gram (20 milligrams). This is the amount
-needed to measure lead-210 and radium-226
-to determine if the lead white is old.</i></p>
-</div>
-<p>In a series of chemical steps, he purified
-the solutions, removing the lead and other
-materials so that finally he had a small
-amount of solution that contained little else
-but the original radium and a very small
-amount of barium (an element that he deliberately
-added and one which is very similar to
-radium in its chemical properties). By adding
-dilute sulfuric acid, he prepared an insoluble
-<span class="pb" id="Page_21">21</span>
-material, barium sulfate, which was barely
-visible suspended in the solution.</p>
-<div class="img" id="fig13">
-<img src="images/p10c.jpg" alt="" width="509" height="799" />
-<p class="pcap"><i>Polonium plating apparatus.
-A heated solution of lead
-white in acetic acid is stirred
-with silver discs for 4 to
-8 hours.</i></p>
-</div>
-<div class="img" id="fig14">
-<img src="images/p10d.jpg" alt="" width="600" height="655" />
-<p class="pcap"><i>The disc above appears
-clean after removal, but
-on its surface it retains a
-minute amount of polonium
-which can be measured.</i></p>
-</div>
-<p>By forcing the solution through a special
-thin plastic filter having tiny holes, the
-particles of barium sulfate together with the
-radium that had been in the solution were
-caught on the surface of the filter. This was
-mounted on a solid disc so that it too could
-be placed in the alpha-particle spectrometer
-for the measurement of radioactivity from the
-radium.</p>
-<p>Two weeks later the results were ready.
-Dad, the boys, and one of the experts from
-the museum met with the chemist to discuss
-them. For one of the two paintings, the
-<span class="pb" id="Page_22">22</span>
-polonium-210 radioactivity was about ten
-times that of the radium activity. The boys
-were disappointed because this meant that
-the painting could not have been 300 or 400
-years old as it first appeared to be.</p>
-<div class="img" id="fig15">
-<img src="images/p11.jpg" alt="" width="1000" height="790" />
-<p class="pcap"><i>An alpha-particle spectrometer is used to measure the radioactivity of the radium and
-polonium prepared from the lead white.</i></p>
-</div>
-<div class="img" id="fig16">
-<img src="images/p11a.jpg" alt="" width="534" height="800" />
-<p class="pcap"><i>A plastic disc on which is
-cemented a filter containing a nearly invisible deposit of barium sulfate (BaSO&#8324;) that
-&ldquo;carried&rdquo; the radium.</i></p>
-</div>
-<p>But in the second painting the radioactivity
-from the polonium-210 and from the
-radium-226 were just about equal. That
-meant that this painting was at least 100 years
-old and, from its appearance, probably more.
-The boys were excited.</p>
-<p>&ldquo;We have a really valuable painting!&rdquo; said
-Martin.</p>
-<p>&ldquo;Not so fast, boys,&rdquo; cautioned Dad. &ldquo;We
-don&rsquo;t know who painted it and we don&rsquo;t
-know exactly how old it is.&rdquo;</p>
-<p>The Gallery&rsquo;s expert was happy too. He
-believed that the second picture was a genuine
-Dutch painting from the 17th century. It was
-<span class="pb" id="Page_23">23</span>
-a landscape and the artist might have been
-Aelbert Cuyp.</p>
-<div class="img" id="fig17">
-<img src="images/p11c.jpg" alt="" width="800" height="553" />
-<p class="pcap"><i>&ldquo;The Maas at Dordrecht&rdquo;, a genuine painting by Aelbert Cuyp.</i></p>
-</div>
-<p>&ldquo;What do we do now?&rdquo; asked Harley.
-&ldquo;How can we prove that the painting was
-painted in Holland in the 17th century by
-Cuyp?&rdquo;</p>
-<p>&ldquo;There is a method now being developed,&rdquo;
-said Dad, &ldquo;that could give us that kind
-of information.&rdquo;</p>
-<p>&ldquo;How does it work?&rdquo; Martin asked.</p>
-<div class="pb" id="Page_24">24</div>
-<h2 id="c3"><span class="small">Who Was the Artist?</span></h2>
-<p>&ldquo;Do you know how criminals are caught
-by using fingerprints?&rdquo; asked Dad.</p>
-<p>&ldquo;Sure we do,&rdquo; said Martin. &ldquo;Each person
-has a set of fingerprints that is different from
-anyone else&rsquo;s.&rdquo;</p>
-<p>Harley spoke up. &ldquo;Did the artist leave his
-fingerprints on the paintings?&rdquo;</p>
-<p>&ldquo;Probably not,&rdquo; said Dad. &ldquo;Besides, they
-would have been wiped off long ago. Also,
-who knows what each artist&rsquo;s fingerprints
-were like?&rdquo;</p>
-<p>&ldquo;Then what do you mean?&rdquo; asked Bill.</p>
-<p>&ldquo;What I mean is, there is another kind of
-&lsquo;fingerprint&rsquo; that scientists are just now learning
-to use in all kinds of identification
-problems. It&rsquo;s not really a fingerprint, but it&rsquo;s
-just as distinctive as a real fingerprint.</p>
-<p>&ldquo;You see, in every material, no matter
-how pure you try to make it, there are always
-other substances contained in it in very, very
-small quantities, which are there only by
-chance. Usually the person making or using
-that material doesn&rsquo;t even know they are
-there, and the quantities are so small they
-don&rsquo;t do any harm. During the last several
-years, scientists have developed extremely
-sensitive methods of analysis, which have
-been applied to all kinds of problems.</p>
-<p>&ldquo;One such method is called neutron activation
-analysis. In this method these small
-amounts of impurities can be detected in tiny
-samples of material. This is quite important
-because only very small samples can be taken
-from a precious painting without damaging it.
-<span class="pb" id="Page_25">25</span>
-Normally, a scientist or an art restorer takes
-samples that are no bigger than the head of a
-pin.&rdquo;</p>
-<p>&ldquo;How can you do anything with a sample
-that small?&rdquo; asked Bill.</p>
-<div class="img">
-<img src="images/p12.jpg" id="ncfig3" alt="uncaptioned" width="800" height="579" />
-</div>
-<p>&ldquo;With neutron activation analysis you can
-do a great deal. To give you an example of
-how sensitive this method is, think of a
-bathtub containing 500 quarts of milk. Add 1
-drop of an acid containing a speck of gold
-dissolved in it. After you mix the acid and
-milk thoroughly, you won&rsquo;t be able to tell by
-looking at it that anything was added. But if
-you take a thimble full of liquid out of the
-bathtub, you can easily tell with neutron
-activation analysis that gold was added to the
-milk.</p>
-<p>&ldquo;Scientists call low concentrations of accidental
-impurities &lsquo;trace elements&rsquo;, and the
-amounts that are present are measured in
-parts per million rather than percent. One
-part per million is one ten-thousandth of a
-percent.&rdquo;</p>
-<p>Bill spoke up again. &ldquo;So how does that
-make a fingerprint, Dad?&rdquo;</p>
-<div class="pb" id="Page_26">26</div>
-<p>&ldquo;It works this way. Suppose an artist used
-lead white in several paintings. Now if the
-lead white were absolutely pure it would
-contain only lead, carbon, oxygen, and hydrogen.
-But the lead white the artist used would
-also contain very small quantities of other
-elements, these trace elements that I spoke of.
-In that particular batch of lead white, certain
-trace elements will be present in a certain
-quantity. The kind and amount of the trace
-elements will be present in that exact pattern
-only in that batch of lead white.</p>
-<p>&ldquo;Now suppose you analyze the lead white
-from several paintings that you know were
-painted by that particular artist, and you find
-that there is silver, mercury, antimony, tin,
-and barium in every one of the samples. Also,
-each of these elements is always present in a
-certain concentration. Suppose also, that you
-have a painting which looks like it was
-painted by that particular artist but you&rsquo;re
-not quite sure.</p>
-<p>&ldquo;Well, if you take a sample of lead white
-from that unknown painting and you find
-that the pattern of impurities is the same as in
-the paintings you knew were genuine, then
-the &lsquo;fingerprints&rsquo; match. The chances of duplicating
-impurities of this kind by pure
-accident are extremely small, just about as
-small as the chances of finding two people
-with the same fingerprints. That&rsquo;s why we call
-this a &lsquo;fingerprint method&rsquo;.&rdquo;</p>
-<p>&ldquo;That sounds like a good idea,&rdquo; said
-Harley. &ldquo;Who thought it up?&rdquo;</p>
-<div class="pb" id="Page_27">27</div>
-<table class="center">
-<tr class="th"><th colspan="6">x = one part per million (ppm)</th></tr>
-<tr class="th"><th class="l" colspan="6">A known Rembrandt.</th></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">silver </td><td class="c">chromium </td><td class="c">zinc </td><td class="c">manganese </td><td class="c">iron </td><td class="c">cobalt</td></tr>
-<tr><td colspan="6" class="c"><hr class="wide" /></td></tr>
-<tr class="th"><th class="l" colspan="6">Unknown painting A</th></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c">x </td><td class="c"> </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c">x </td><td class="c"> </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c"> </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">silver </td><td class="c">chromium </td><td class="c">zinc </td><td class="c">manganese </td><td class="c">iron </td><td class="c">cobalt</td></tr>
-<tr><td colspan="6" class="c"><hr class="wide" /></td></tr>
-<tr class="th"><th class="l" colspan="6">Unknown painting B</th></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c"> </td><td class="c">x </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c"> </td><td class="c">x </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">silver </td><td class="c">chromium </td><td class="c">zinc </td><td class="c">manganese </td><td class="c">iron </td><td class="c">cobalt</td></tr>
-<tr><td colspan="6" class="c"><hr class="wide" /></td></tr>
-<tr class="th"><th class="l" colspan="6">Known forgery</th></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c"> </td><td class="c"> </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c">x </td><td class="c"> </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c"> </td><td class="c">x </td><td class="c"> </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c"> </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x </td><td class="c">x</td></tr>
-<tr><td class="c">silver </td><td class="c">chromium </td><td class="c">zinc </td><td class="c">manganese </td><td class="c">iron </td><td class="c">cobalt</td></tr>
-</table>
-<p class="pcap"><i>Match the patterns of these lead white &ldquo;fingerprints&rdquo;. Unknown
-painting A is</i> <b>not</b> <i>a Rembrandt; it</i> <b>is</b> <i>by the same forger who painted the
-known forgery at the bottom. Unknown painting B is either by
-Rembrandt, one of his fellow citizens, or one of his students using the
-same paint.</i></p>
-<div class="pb" id="Page_28">28</div>
-<p>&ldquo;It was thought of many times by many
-people. But, it&rsquo;s never been used for identifying
-paintings. In 1964 in the Netherlands, two
-scientists, named Houtman and Turkstra,
-analyzed about 40 different samples of lead
-white, 20 of which came from Dutch and
-Flemish paintings. The rest were samples of
-lead white not taken from paintings but
-obtained directly from the manufacturers.
-They analyzed these samples for different
-elements. These included silver, mercury,
-chromium, manganese, tin, antimony, and a
-couple of others.</p>
-<p>&ldquo;They found that the concentrations of
-these elements in the lead white from all the
-old Dutch and Flemish paintings were very
-similar. And the trace element concentrations
-were quite different in the modern lead white
-samples analyzed in the same way. At the
-time, they presumed that it was because the
-lead white in the paintings was manufactured
-so long ago. They may have been right to a
-certain extent.</p>
-<p>&ldquo;For example, they found that in all the
-old paintings there were from 10 to 30 parts
-per million of silver in the lead white, while in
-the modern samples of this pigment there
-were generally less than 10 parts per million
-of silver. All of them had been painted before
-the 19th century, and all the samples of pure
-lead white were manufactured during the
-latter part of the 19th century or during the
-20th century. They believed that the reason
-the silver concentration was lower in the more
-modern material was because during the 19th
-century, lead refiners were doing a better job
-of removing all the valuable silver from lead.</p>
-<div class="pb" id="Page_29">29</div>
-<div class="img" id="fig18">
-<img src="images/p14.jpg" alt="" width="800" height="459" />
-<p class="pcap"><i>Silver concentrations in lead white. The concentrations generally
-decreased after the middle 1800s. Notice also how the concentrations
-were very similar for all the older paintings (before 1700) which were
-Dutch or Flemish.</i></p>
-</div>
-<p>&ldquo;However, in 1967 in Germany, two
-men, named Lux and Braunstein, discovered
-that in some old paintings produced
-in Italy, lead white also contained low quantities
-of silver just like modern material. They
-believed that the higher concentrations of
-silver in lead white were typical of Dutch and
-Flemish painters while the lower concentrations
-were typical of Italian paintings of
-about the same age.</p>
-<p>&ldquo;The whole case is still unsettled because
-not enough measurements have been made to
-show how reliable this method can be. That
-is, no one knows if samples of paint from
-several paintings by one artist would all have
-the same pattern of impurities in the same
-pigment. It may be that of the many pigments
-present in an artist&rsquo;s paintings only a few will
-<span class="pb" id="Page_30">30</span>
-be suitable for use in this &lsquo;fingerprinting&rsquo;
-method.&rdquo;</p>
-<div class="img" id="fig19">
-<img src="images/p15.jpg" alt="" width="559" height="800" />
-<p class="pcap"><i>Quartz vials (right) containing
-samples are sealed
-in the aluminum can on
-the left. They are then
-bombarded with neutrons
-in a reactor like the one in
-the picture below.</i></p>
-</div>
-<p>&ldquo;It sounds complicated,&rdquo; said Bill.</p>
-<p>&ldquo;It is, and it&rsquo;s going to take years of work
-before the method is proven, if it is at all. It
-may turn out that you can&rsquo;t tell one artist
-from another, but only groups of artists like
-17th century Dutch painters or 19th century
-English painters.&rdquo;</p>
-<p>&ldquo;Tell us something about neutron activation
-analysis,&rdquo; said Martin. &ldquo;How do you
-measure such small amounts of impurities?&rdquo;</p>
-<p>&ldquo;The best way to tell you how this works
-is to show you. How would you boys like to
-visit a laboratory where neutron activation
-analysis is being done?&rdquo;</p>
-<p>&ldquo;Do you have to ask?&rdquo; said Harley. &ldquo;Of
-course we would!&rdquo;</p>
-<p>A few weeks later it was all arranged. At a
-laboratory close by a nuclear reactor, the boys
-watched a radiochemist place a few specks of
-material inside small quartz tubes that were
-then sealed. The tubes were put in an aluminum
-can and placed in the nuclear reactor.
-The can was fastened on the end of a long
-pole that was then submerged in a deep pool
-of water. At the bottom of the pool the boys
-could see a bright blue glow.</p>
-<div class="img" id="fig20">
-<img src="images/p15b.jpg" alt="" width="580" height="800" />
-<p class="pcap"><i>This type of nuclear reactor
-is used for neutron
-activation analysis.</i></p>
-</div>
-<p>&ldquo;So that&rsquo;s what a nuclear reactor looks
-like!&rdquo; said Bill.</p>
-<p>&ldquo;Yes,&rdquo; said Dad. &ldquo;Where you see the blue
-glow you can also see rows of fuel elements.
-Each one contains slugs of uranium encased in
-aluminum. This is one of a number of
-different types of reactors. But every nuclear
-reactor is arranged so that the uranium atoms
-<span class="pb" id="Page_31">31</span>
-divide (or fission) many, many times each
-second.</p>
-<p>&ldquo;When this happens, heat is produced that
-is carried away by the water, and also many,
-many free neutrons are produced. Those
-samples, placed down next to the reactor in
-the bottom of the pool are being bombarded
-by the neutrons, and some of the elements in
-the samples absorb the neutrons and become
-radioactive.&rdquo;</p>
-<p>After a while the samples were removed
-and carried back to the laboratory in a lead
-box. A short while later, the radiochemist
-opened the aluminum can, broke open the
-quartz capsules, and removed the samples for
-analysis. The boys watched the chemist
-mount each sample on a card and take it to a
-room where there was equipment for measuring
-radioactivity.</p>
-<div class="img" id="fig21">
-<img src="images/p15c.jpg" alt="" width="800" height="376" />
-<p class="pcap"><i>Gamma-ray spectrometer. The sample to be measured is placed on a
-stand over a gamma-ray detector. The pulse-height analyzer is a device
-that sorts electrical impulses from the detector according to the energy
-of the gamma rays causing the impulses. The screen displays the
-gamma-ray spectrum and the electric typewriter automatically types
-out the data collected when the measurement is complete.</i></p>
-</div>
-<div class="pb" id="Page_32">32</div>
-<p>One by one the samples were placed
-inside a shield consisting of a big pile of lead
-bricks. When the heavy door was opened, the
-boys could see a metal can inside the shield,
-which housed a detector (called a lithium-drifted
-germanium detector) that measured
-the gamma rays emitted by the sample. As
-each sample was placed near the detector the
-chemist turned on a gamma-ray spectrometer
-to which the detector was connected.</p>
-<p class="pcapc">A tiny sample of lead white <img class="inline" src="images/x1.png" alt="sample" width="44" height="28" />
-is sealed in a quartz vial <img class="inline" src="images/x2.png" alt="vial" width="56" height="32" /> which
-is bombarded with neutrons in a reactor.</p>
-<div class="img">
-<img src="images/p16.jpg" id="ncfig4" alt="uncaptioned" width="333" height="234" />
-</div>
-<p class="pcapc">Many of the atoms become radioactive, emitting gamma rays.</p>
-<div class="img">
-<img src="images/p16c.jpg" id="ncfig5" alt="uncaptioned" width="700" height="331" />
-</div>
-<p class="pcapc">The sample is placed in a gamma-ray spectrometer and the gamma rays
-are separated according to their energy.</p>
-<div class="img">
-<img src="images/p16d.jpg" id="ncfig6" alt="uncaptioned" width="600" height="391" />
-</div>
-<dl class="undent pcap"><dt>Gamma-ray spectrum</dt>
-<dd>Copper</dd>
-<dd>Zinc</dd>
-<dd>Antimony</dd>
-<dd>Lead</dd>
-<dd>Silver</dd>
-<dd>Height</dd>
-<dd>Antimony</dd></dl>
-<p class="pcapc">The location (energy) of
-each peak indicates what
-is present and the height
-indicates how much!</p>
-<div class="pb" id="Page_33">33</div>
-<div class="img" id="fig22">
-<img src="images/p16e.jpg" alt="" width="1000" height="718" />
-<p class="pcap"><i>A gamma-ray spectrum as it appears on the screen of a pulse-height
-analyzer. The gamma-ray peaks are marked with the name of the
-element whose radioactive isotope emits the gamma ray; two for cobalt
-and zinc and one for cesium.</i></p>
-</div>
-<p>There, on what looked like a small television
-screen, flashes of light appeared that
-gradually formed a curve with many peaks
-and valleys. After a few minutes the spectrometer
-was stopped and an electric typewriter
-automatically typed out rows and
-columns of numbers.</p>
-<p>The chemist explained, &ldquo;This curve,
-which you see on the screen, is a gamma-ray
-spectrum and tells us what elements are in the
-sample. The typed-out data give us an accurate
-measure of the shape of the curve on
-the screen. By measuring the gamma-rays&rsquo;
-energies we know what elements in the
-sample were made radioactive. The height of
-<span class="pb" id="Page_34">34</span>
-each gamma-ray peak tells us how much of
-that element is present in the sample.</p>
-<p>&ldquo;That gives us the information we need to
-calculate the concentrations of the small
-quantities of materials in our samples. We can
-do this because at the same time I irradiated a
-set of standards. Standards are materials that
-are just like the samples except that they
-contain known amounts of the impurities I
-am trying to measure.&rdquo;</p>
-<p>As the boys were leaving the laboratory,
-the chemist apologized for not having enough
-time to explain the activation analysis procedure
-more thoroughly, but he did give the
-boys a list of books to read on the subject of
-radioactivity and radioisotopes.<a class="fn" id="fr_2" href="#fn_2">[2]</a> They
-thanked him for his help.</p>
-<p>During the ride home, they discussed the
-paintings that were still unproven.</p>
-<p>&ldquo;It&rsquo;s too bad that the method of activation
-analysis fingerprinting hasn&rsquo;t been fully
-developed yet,&rdquo; said Dad.</p>
-<p>&ldquo;Yes,&rdquo; said Bill. &ldquo;Then we could prove
-whether or not that last old painting was
-really by Aelbert Cuyp as the expert from the
-gallery believed. But what about those paintings
-that we found in the box that were not
-so old?&rdquo;</p>
-<p>&ldquo;Well,&rdquo; said Dad, &ldquo;if the activation analysis
-method were workable, we might be able
-to prove if they were painted by Alfred
-Sisley. Meanwhile, until the method is really
-developed we don&rsquo;t know if we can do it that
-way or not.&rdquo;</p>
-<div class="pb" id="Page_35">35</div>
-<p>&ldquo;So what do we do now?&rdquo; asked Martin.</p>
-<p>&ldquo;We&rsquo;ll have to wait until scientists can
-thoroughly investigate this method and
-several others that they&rsquo;re working on.&rdquo;</p>
-<p>&ldquo;Other methods!&rdquo; exclaimed Bill. &ldquo;What
-other methods?&rdquo;</p>
-<div class="img" id="fig23">
-<img src="images/p17.jpg" alt="" width="1200" height="956" />
-<p class="pcap"><i>&ldquo;The Banks of the Oise&rdquo;, a genuine painting by Alfred Sisley.</i></p>
-</div>
-<div class="pb" id="Page_36">36</div>
-<h2 id="c4"><span class="small">Other New Tools for Art Authentication</span></h2>
-<p>&ldquo;There are several new tools that scientists
-are working on now,&rdquo; said Dad. &ldquo;These
-involve methods that have been developed by
-scientists for other purposes, but are now
-being explored for use in authenticating
-works of art.</p>
-<p>&ldquo;For example, in Los Angeles, the county
-museum purchased an instrument known as a
-Spark Source Mass Spectrometer. Like activation
-analysis, this instrument will also measure
-small traces of impurities, but they have
-just set that up and it will take them years to
-explore the use of it for the type of problem
-we have been discussing.</p>
-<p>&ldquo;X-ray diffraction is another method that
-has been around for quite awhile but hasn&rsquo;t
-been used much for art identification until
-recently. With X-ray diffraction, samples of
-pigments can be identified by the pattern
-formed when X rays are bent by passing
-through the sample of pigment.&rdquo;</p>
-<p>&ldquo;How&rsquo;s that?&rdquo; asked Harley.</p>
-<p>&ldquo;There are 3 or 4 different compounds
-with about the same chemical composition as
-lead white. Chemically, they are almost impossible
-to distinguish. But with X-ray diffraction,
-a chemist can easily tell them apart. The
-hope is that the type of lead white will
-indicate how it was manufactured. Until the
-middle of the 19th century, lead white was
-produced mainly by packing strips of lead in
-clay pots with a little vinegar in the bottom.
-The clay pots were stacked in a large building
-with layers of decaying organic matter on the
-<span class="pb" id="Page_37">37</span>
-floor. The building was sealed for several
-weeks during which time the lead corroded in
-the fumes and became covered with a white
-substance. The white substance, lead white,
-was scraped off, ground, and washed to make
-the pigment.</p>
-<p>&ldquo;But, in the 19th century, when
-people began to learn more about chemistry,
-they looked for faster ways of
-making lead white and some of these
-methods produced a lead white of somewhat
-different composition. By using X-ray diffraction,
-chemists now hope that they can tell
-how the lead white was manufactured. This
-may provide another means of dating the lead
-white in a painting.&rdquo;</p>
-<p>&ldquo;Are there any other methods?&rdquo; asked
-Harley.</p>
-<div class="img" id="fig24">
-<img src="images/p18.jpg" alt="" width="694" height="800" />
-<p class="pcap"><i>The stack process for making
-lead white. Rows of
-clay pots containing lead
-and vinegar are packed to
-the ceiling of the building,
-and fermenting tanbark on
-the floor produces carbon
-dioxide and heat. The
-fumes of vinegar and the
-carbon dioxide corrode
-the lead in 2 to 4 months,
-and the corrosion is lead
-white.</i></p>
-</div>
-<p>&ldquo;Yes, isotope mass spectrometry is one.
-All lead consists of 4 different isotopes or
-atoms of different weights. Three of these 4
-<span class="pb" id="Page_38">38</span>
-are the end products of a radioactive decay
-chain. Depending upon the history of the
-rock formation in which the lead ore occurred,
-the relative amounts of the lead
-isotopes vary in a special way. In other words,
-if we know the different amounts of lead
-isotopes in the world&rsquo;s lead ore deposits, and
-we have a sample of lead white from a
-painting, we can tell from which deposit the
-lead, which formed the lead white, came. If,
-for example, we find that the isotope pattern
-in a sample from a painting is the same as in
-lead ore from Australia, then the painting
-can&rsquo;t be very old because lead white wasn&rsquo;t
-produced from lead mined in Australia until
-about 100 years ago.&rdquo;</p>
-<div class="img" id="fig25">
-<img src="images/p19.jpg" alt="" width="800" height="688" />
-<p class="pcap"><i>X-ray diffraction patterns from three different lead compounds that
-might occur in lead white. The middle one is the ideal lead white
-produced for over 2000 years. While some of the bottom compound
-may be found mixed with it, the compound shown at the top is only a
-20th-century invention.</i></p>
-</div>
-<dl class="undent pcap"><dt>4PbCO&#8323; &middot; 2PB(OH)&#8322; &middot; PbO</dt>
-<dt>2PbCO&#8323; &middot; PB(OH)&#8322;</dt>
-<dt>PbCO&#8323;</dt></dl>
-<div class="pb" id="Page_39">39</div>
-<p>&ldquo;How do you measure lead isotopes?&rdquo;
-asked Harley.</p>
-<p>&ldquo;With an instrument called a mass spectrometer.
-This instrument is capable of
-separating the lead isotopes. First, the atoms
-of lead in the sample are electrically charged
-and &lsquo;fired&rsquo; in a beam down the length of a
-tube between the poles of a strong magnet.
-There, the charged atoms (or ions) in the
-beam are deflected by different amounts
-according to how heavy they are. Thus the
-different isotopes are separated. This method
-is also still being studied and, although it
-shows great promise, it will be some time
-before it can solve problems of art identification.
-Also the study of the natural variation in
-isotopes of other elements, such as sulfur,
-is useful for identification of other pigments
-as well.</p>
-<div class="img" id="fig26">
-<img src="images/p19a.jpg" alt="" width="800" height="430" />
-<p class="pcap"><i>Diagram of a simple mass spectrometer. The ionized atoms of lead
-travel in a beam at the same speed. The heavier atoms bend less than
-the lighter ones when the beam passes the magnet. Thus two beams
-emerge instead of one. Actually there are four isotopes of lead so there
-will be four beams.</i></p>
-</div>
-<div class="pb" id="Page_40">40</div>
-<div class="img" id="fig27">
-<img src="images/p20.jpg" alt="" width="588" height="792" />
-<p class="pcap"><i>&ldquo;Agostina&rdquo;, a genuine
-painting by Jean Baptiste
-Camille Corot.</i></p>
-</div>
-<p>&ldquo;Another new method that shows great
-promise has been developed, but this one is
-not applicable to the paintings that you boys
-found in the box.&rdquo;</p>
-<p>&ldquo;Why not?&rdquo; asked Bill.</p>
-<p>&ldquo;Since the Second World War, the art
-forgery business has been growing rapidly.
-For example, it has been said that of the 2000
-pictures that Corot, a 19th century Frenchman,
-is known to have painted, more than
-5000 of them are in the United States. This
-may be only a humorous exaggeration, but a
-large number of forgeries have been produced
-in the last several years. These are usually
-supposed to be paintings that are less than
-100 years old. Present-day forgers like to
-forge paintings that aren&rsquo;t very old because
-it&rsquo;s easier to get away with. Now this new
-method, which will detect such recent forgeries,
-is based upon the presence of carbon-14, a
-radioactive isotope of carbon, in our atmosphere
-and in all things that grow on our
-planet.</p>
-<p>&ldquo;Ordinarily, carbon-14 is produced only
-by cosmic rays, and its concentrations in the
-atmosphere and in growing things would
-remain at a constant level. But since the
-middle of the 1950s the testing of nuclear
-weapons has increased the amount of radioactive
-carbon in our atmosphere by quite a
-bit. Many artist&rsquo;s materials, such as linseed oil,
-canvas, paper, and so on, come from plants or
-animals, and so will contain the same concentrations
-of carbon-14 as the atmosphere
-up to the time that the plant or animal dies.</p>
-<div class="pb" id="Page_41">41</div>
-<p>&ldquo;Therefore, linseed oil (from the flax
-plant), for example, produced during the last
-few years will have a much greater concentration
-of carbon-14 in it than linseed oil
-produced more than 20 years ago. Scientists
-at Carnegie-Mellon University have shown
-that this method will work. It is only a matter
-of making the measurements on the small
-samples available from presumably valuable
-paintings.&rdquo;</p>
-<div class="img" id="fig28">
-<img src="images/p20a.jpg" alt="" width="1000" height="928" />
-<p class="pcap"><i>The changing concentrations of carbon-14 in our atmosphere. High
-levels of carbon-14 in linseed oil and other painting materials will
-indicate that a work of art is only a few years old.</i></p>
-</div>
-<dl class="undent pcap"><dt>Carbon-14 radioactivity</dt>
-<dd>Older materials contain less as the carbon-14 decays away.</dd>
-<dd>In this period, decrease is due to the burning of large quantities of coal and oil as industry grew. This diluted the newly formed carbon-14.</dd>
-<dd>Increases due to testing of atomic weapons in the atmosphere.</dd>
-<dt>Carbon-14 produced by cosmic rays only</dt>
-<dd>Neutron &rarr; Nitrogen &rarr; Carbon-14 + proton</dd>
-<dd>Carried down by rain in carbon dioxide</dd></dl>
-<p>&ldquo;There are also a number of other
-methods being studied including the use of
-Messbauer Effect Spectroscopy to study pigments
-<span class="pb" id="Page_42">42</span>
-that contain iron, thermoluminescent
-dating of pottery and terra-cotta statuary,
-X-ray fluorescence analysis as a general tool,
-and neutron autoradiography as a means of
-studying the technique of artists. You can
-read all about them if you wish.&rdquo;<a class="fn" id="fr_3" href="#fn_3">[3]</a></p>
-<p>&ldquo;It sounds like forgers are going to have a
-tough time in the future,&rdquo; said Harley.</p>
-<p>&ldquo;That&rsquo;s right. It may even turn out that
-producing forgeries to pass all these new tests
-will be so difficult and expensive that forgers
-will stop trying.&rdquo;</p>
-<h2 id="c5"><span class="small">One Mystery Solved</span></h2>
-<p>A year later an important letter arrived at
-the boys&rsquo; house. Dad opened it, read it
-quickly, and said, &ldquo;Good news, boys! This
-letter is from the Dutch government. Remember
-those two paintings that we thought
-might have been stolen from a Dutch
-museum?&rdquo;</p>
-<p>&ldquo;Yes,&rdquo; said Bill.</p>
-<p>&ldquo;Well, it seems that after a year of
-studying them, the Dutch have decided that
-they really are the paintings that were
-stolen.&rdquo;</p>
-<p>&ldquo;That is good news,&rdquo; said Harley. &ldquo;At
-least we know that two of the paintings we
-found are genuine.&rdquo;</p>
-<p>&ldquo;What are they going to do with them?&rdquo;
-asked Martin.</p>
-<p>&ldquo;Of course, they have to go back to their
-original owners. But this letter says that the
-<span class="pb" id="Page_43">43</span>
-Dutch government wants us to come to
-Holland as their guests as a reward for finding
-those paintings.&rdquo;</p>
-<div class="img" id="fig29">
-<img src="images/p21.jpg" alt="" width="800" height="452" />
-<p class="pcap"><i>These two paintings &ldquo;The Lacemaker&rdquo; and &ldquo;The Smiling Girl&rdquo; were
-thought to have been by Vermeer. A series of tests, including some of
-those described in this booklet, showed that the paintings are fairly old.
-However, some of the materials used are not typical of Vermeer, and the
-pictures are now thought to have been painted by a follower of the artist.</i></p>
-</div>
-<p>&ldquo;That&rsquo;s great!&rdquo; said Bill. &ldquo;Looks like
-we&rsquo;re getting something out of finding that
-box after all.&rdquo;</p>
-<p>&ldquo;Yes,&rdquo; said Dad. &ldquo;And don&rsquo;t forget the
-other unidentified paintings may also be
-genuine. We&rsquo;ve proved that one is a fake, the
-experts believe that three of the others are
-copies, and then there are the two that might
-be Sisleys and are only waiting for a method
-to prove it. And we have one more that
-science managed to prove was really old. I&rsquo;m
-sure that in a few years methods will be
-developed to tell us exactly who painted it.</p>
-<p>&ldquo;And now let&rsquo;s make arrangements for
-our trip to Holland.&rdquo;</p>
-<div class="pb" id="Page_44">44</div>
-<h2 id="c6"><span class="small">Reading List</span></h2>
-<p class="revint"><i>About Atomic Power for People</i>, Edward and
-Ruth S. Radlauer, Childrens Press, Chicago,
-Illinois 60607, 1960, 47 pp., $2.50. Grades
-5-9.</p>
-<p class="revint"><i>All About the Atom</i>, Ira M. Freeman, Random
-House, Inc., New York 10022, 1955,
-146 pp., $2.50. Grades 4-6.</p>
-<p class="revint"><i>Atoms at Your Service</i>, Henry A. Dunlap and
-Hans N. Tuch, Harper and Row, Publishers,
-New York 10016, 1957, 167 pp., $4.00.
-Grades 7-9.</p>
-<p class="revint"><i>Carbon-14 and Other Science Methods that
-Date the Past</i>, Lynn and Gray Poole,
-McGraw-Hill Book Company, New York
-10036, 1961, 160 pp., $3.95. Grades 9-12.</p>
-<p class="revint"><i>Experiments with Atomics</i> (revised edition),
-Nelson F. Beeler and Franklyn M. Branley,
-Crowell Collier and Macmillan, Inc., New
-York 10022, 1965, 160 pp., $3.50. Grades
-5-8.</p>
-<p class="revint"><i>The Fabulous Isotopes: What They Are and
-What They Do</i>, Robin McKown, Holiday
-House, Inc., New York 10022, 1962,
-189 pp., $4.50. Grades 7-10.</p>
-<p class="revint"><i>Inside the Atom</i> (revised edition), Isaac
-Asimov, Abelard-Schuman, Ltd., New York
-10019, 1966, 197 pp., $4.00. Grades 7-10.</p>
-<p class="revint"><i>Introducing the Atom</i>, Roslyn Leeds, Harper
-and Row, Publishers, New York 10016,
-1967, 224 pp., $3.95. Grades 7-9.</p>
-<p class="revint"><i>Our Friend the Atom</i>, Heinz Haber, Golden
-Press, Inc., New York 10022, 1957,
-165 pp., $4.95 (out of print but available
-through libraries); $0.35 (paperback) from
-<span class="pb" id="Page_45">45</span>
-Dell Publishing Company, Inc., New York
-10017. Grades 7-9.</p>
-<p class="revint"><i>Radioisotopes</i>, John H. Woodburn, J. B.
-Lippincott Company, Philadelphia, Pennsylvania
-19105, 1962, 128 pp., $3.50. Grades
-7-10.</p>
-<p class="revint"><i>The Story of Atomic Energy</i>, Laura Fermi,
-Random House, Inc., New York 10022,
-1961, 184 pp., $1.95. Grades 7-11.</p>
-<p class="revint"><i>The Useful Atom</i>, William R. Anderson and
-Vernon Pizer, The World Publishing Company,
-New York 10022, 1966, 185 pp.,
-$5.75. Grades 7-12.</p>
-<p class="revint"><i>Working with Atoms</i>, Otto R. Frisch, Basic
-Books, Inc., Publishers, New York 10016,
-1965, 96 pp., $3.50. Grades 9-12.</p>
-<h3>Footnotes</h3>
-<div class="fnblock"><div class="fndef"><a class="fn" id="fn_1" href="#fr_1">[1]</a>It is called this because 210 is the total number of
-protons and neutrons in its nucleus.
-</div><div class="fndef"><a class="fn" id="fn_2" href="#fr_2">[2]</a>See the reading list on <a href="#Page_44">page 44</a>.
-</div><div class="fndef"><a class="fn" id="fn_3" href="#fr_3">[3]</a>See <i>Secrets of the Past: Nuclear Science and Archaeology</i>,
-which is listed on the <a href="#Page_47">inside back cover</a> of this booklet.
-</div>
-</div>
-<h3 id="c7">PHOTO CREDITS</h3>
-<p><a href="#cover">Cover</a> courtesy Groninger Museum voor stad en Lande</p>
-<div class="forcesf">
-<table class="center">
-<tr class="th"><th>Page</th></tr>
-<tr><td class="c"><a href="#Page_5">5</a> </td><td class="l">Yale Joel, <i>Life</i> magazine, copyright &copy; Time, Inc.</td></tr>
-<tr><td class="c"><a href="#Page_6">6</a> </td><td class="l">Her Majesty the Queen, copyright &copy; reserved</td></tr>
-<tr><td class="c"><a href="#Page_7">7</a> &amp; <a href="#Page_8">8</a> </td><td class="l">Ullstein Bilderdienst</td></tr>
-<tr><td class="c"><a href="#Page_10">10</a> </td><td class="l">Rijksmuseum, Amsterdam</td></tr>
-<tr><td class="c"><a href="#Page_23">23</a> </td><td class="l">National Gallery of Art, Washington, D. C., Andrew Mellon Collection</td></tr>
-<tr><td class="c"><a href="#Page_35">35</a> &amp; <a href="#Page_40">40</a> </td><td class="l">National Gallery of Art, Washington, D. C., Chester Dale Collection</td></tr>
-<tr><td class="c"><a href="#Page_43">43</a> </td><td class="l">National Gallery of Art, Washington, D. C., Andrew Mellon Collection</td></tr>
-</table>
-</div>
-<p class="jr1"><span class="ss"><span class="smallest">&#9733; U.S. GOVERNMENT PRINTING OFFICE: 1974&mdash;747-556/15</span></span></p>
-<div class="pb" id="Page_47">47</div>
-<hr class="dwide" />
-<p>The U. S. Atomic Energy Commission publishes this series of information
-booklets for the general public. The booklets are listed below by subject
-category.</p>
-<p>If you would like to have copies of these booklets, please write to the
-following address for a booklet price list:</p>
-<div class="verse">
-<p class="t0">USAEC&mdash;Technical Information Center</p>
-<p class="t0">P. O. Box 62</p>
-<p class="t0">Oak Ridge, Tennessee 37830</p>
-</div>
-<p>School and public libraries may obtain a complete set of the booklets
-without charge. These requests must be made on school or library stationery.</p>
-<table class="center">
-<tr class="th"><th class="l" colspan="2">Chemistry</th></tr>
-<tr><td class="l">IB-303 </td><td class="l">The Atomic Fingerprint: Neutron Activation Analysis</td></tr>
-<tr><td class="l">IB-301 </td><td class="l">The Chemistry of the Noble Gases</td></tr>
-<tr><td class="l">IB-302 </td><td class="l">Cryogenics: The Uncommon Cold</td></tr>
-<tr><td class="l">IB-304 </td><td class="l">Nuclear Clocks</td></tr>
-<tr><td class="l">IB-306 </td><td class="l">Radioisotopes in Industry</td></tr>
-<tr><td class="l">IB-307 </td><td class="l">Rare Earths: The Fraternal Fifteen</td></tr>
-<tr><td class="l">IB-308 </td><td class="l">Synthetic Transuranium Elements</td></tr>
-<tr class="th"><th class="l" colspan="2">Biology</th></tr>
-<tr><td class="l">IB-101 </td><td class="l">Animals in Atomic Research</td></tr>
-<tr><td class="l">IB-102 </td><td class="l">Atoms in Agriculture</td></tr>
-<tr><td class="l">IB-105 </td><td class="l">The Genetic Effects of Radiation</td></tr>
-<tr><td class="l">IB-110 </td><td class="l">Preserving Food with Atomic Energy</td></tr>
-<tr><td class="l">IB-106 </td><td class="l">Radioisotopes and Life Processes</td></tr>
-<tr><td class="l">IB-107 </td><td class="l">Radioisotopes in Medicine</td></tr>
-<tr><td class="l">IB-109 </td><td class="l">Your Body and Radiation</td></tr>
-<tr class="th"><th class="l" colspan="2">The Environment</th></tr>
-<tr><td class="l">IB-201 </td><td class="l">The Atom and the Ocean</td></tr>
-<tr><td class="l">IB-202 </td><td class="l">Atoms, Nature, and Man</td></tr>
-<tr><td class="l">IB-414 </td><td class="l">Nature&rsquo;s Invisible Rays</td></tr>
-<tr class="th"><th class="l" colspan="2">General Interest</th></tr>
-<tr><td class="l">IB-009 </td><td class="l">Atomic Energy and Your World</td></tr>
-<tr><td class="l">IB-010 </td><td class="l">Atomic Pioneers&mdash;Book 1: From Ancient Greece to the 19th Century</td></tr>
-<tr><td class="l">IB-011 </td><td class="l">Atomic Pioneers&mdash;Book 2: From the Mid-19th to the Early 20th Century</td></tr>
-<tr><td class="l">IB-012 </td><td class="l">Atomic Pioneers&mdash;Book 3: From the Late 19th to the Mid-20th Century</td></tr>
-<tr><td class="l">IB-002 </td><td class="l">A Bibliography of Basic Books on Atomic Energy</td></tr>
-<tr><td class="l">IB-004 </td><td class="l">Computers</td></tr>
-<tr><td class="l">IB-008 </td><td class="l">Electricity and Man</td></tr>
-<tr><td class="l">IB-005 </td><td class="l">Index to AEC Information Booklets</td></tr>
-<tr><td class="l">IB-310 </td><td class="l">Lost Worlds: Nuclear Science and Archeology</td></tr>
-<tr><td class="l">IB-309 </td><td class="l">The Mysterious Box: Science and Art</td></tr>
-<tr><td class="l">IB-006 </td><td class="l">Nuclear Terms: A Glossary</td></tr>
-<tr><td class="l">IB-013 </td><td class="l">Secrets of the Past: Nuclear Energy Applications in Art and Archaeology</td></tr>
-<tr><td class="l">IB-017 </td><td class="l">Teleoperators: Man&rsquo;s Machine Partners</td></tr>
-<tr><td class="l">IB-014, 015, &amp; 016 </td><td class="l">Worlds Within Worlds: The Story of Nuclear Energy Volumes 1, 2, and 3</td></tr>
-<tr class="th"><th class="l" colspan="2">Physics</th></tr>
-<tr><td class="l">IB-401 </td><td class="l">Accelerators</td></tr>
-<tr><td class="l">IB-402 </td><td class="l">Atomic Particle Detection</td></tr>
-<tr><td class="l">IB-403 </td><td class="l">Controlled Nuclear Fusion</td></tr>
-<tr><td class="l">IB-404 </td><td class="l">Direct Conversion of Energy</td></tr>
-<tr><td class="l">IB-410 </td><td class="l">The Electron</td></tr>
-<tr><td class="l">IB-405 </td><td class="l">The Elusive Neutrino</td></tr>
-<tr><td class="l">IB-416 </td><td class="l">Inner Space: The Structure of the Atom</td></tr>
-<tr><td class="l">IB-406 </td><td class="l">Lasers</td></tr>
-<tr><td class="l">IB-407 </td><td class="l">Microstructure of Matter</td></tr>
-<tr><td class="l">IB-415 </td><td class="l">The Mystery of Matter</td></tr>
-<tr><td class="l">IB-411 </td><td class="l">Power from Radioisotopes</td></tr>
-<tr><td class="l">IB-413 </td><td class="l">Spectroscopy</td></tr>
-<tr><td class="l">IB-412 </td><td class="l">Space Radiation</td></tr>
-<tr class="th"><th class="l" colspan="2">Nuclear Reactors</th></tr>
-<tr><td class="l">IB-501 </td><td class="l">Atomic Fuel</td></tr>
-<tr><td class="l">IB-502 </td><td class="l">Atomic Power Safety</td></tr>
-<tr><td class="l">IB-513 </td><td class="l">Breeder Reactors</td></tr>
-<tr><td class="l">IB-503 </td><td class="l">The First Reactor</td></tr>
-<tr><td class="l">IB-505 </td><td class="l">Nuclear Power Plants</td></tr>
-<tr><td class="l">IB-507 </td><td class="l">Nuclear Reactors</td></tr>
-<tr><td class="l">IB-510 </td><td class="l">Nuclear Reactors for Space Power</td></tr>
-<tr><td class="l">IB-508 </td><td class="l">Radioactive Wastes</td></tr>
-<tr><td class="l">IB-511 </td><td class="l">Sources of Nuclear Fuel</td></tr>
-<tr><td class="l">IB-512 </td><td class="l">Thorium and the Third Fuel</td></tr>
-</table>
-<div class="img">
-<img src="images/p30.jpg" id="ncfig7" alt="AEC logo" width="310" height="318" />
-</div>
-<p class="center"><span class="rubric ss">U. S. ATOMIC ENERGY COMMISSION
-<br />Office of Information Services</span></p>
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