Rediscovering the Elements

During the past 25 years, chemistry professor James L. Marshall of the University of North Texas, Denton, has collected pure samples of nearly all the elements from hydrogen through uranium. In addition, he has collected a variety of mineral samples representing all the elements and many objects made from each element that are used in commercial applications.

That's impressive enough, but there's more: During the past six years, Marshall and his wife, Virginia (Jenny), have managed to obtain mineral samples for each element from the original site where the element is known to have been discovered. Finding these "discovery" samples has required much sleuthing in museums, archives, personal papers, and the chemical literature, as well as a lot of travel to collecting sites about the globe.

The Marshalls call their effort "Rediscovery of the Elements," and they are in the process of writing a book and accompanying CD to share with the chemical community their unique knowledge of the history of the elements.

Early on, the Marshalls' element and mineral collection attracted the attention of neurologist Oliver Sacks, who visited them in 2000 [J. Chem. Educ., 80, 879 (2003)]. The visit came about a year before publication of Sacks's well-received book "Uncle Tungsten: Memories of a Chemical Boyhood."

Sacks recalls the excitement he felt on seeing the original minerals from which the elements were obtained. "I sensed a huge richness--an immediate warmth--in examining the collection," he tells C&EN. "There's a museum-like quality about it, but a highly personal quality as well. Equally wonderful are the stories of the places and people, the excursions into history and the geography. The details of how they have rediscovered the elements will make for a quite beautiful book."

Jim Marshall began collecting elements in earnest in the early 1980s when he was head of Motorola's Manufacturing Technology Group in Fort Worth. Previously, he had been a chemistry professor at the University of North Texas, where he had developed a research program involving conformational analysis of organic compounds using ¹³C nuclear magnetic resonance coupling constants. At Motorola, the focus was on materials science, and as part of his job, Marshall spent a lot of time traveling. He started picking up interesting samples of materials from different Motorola sites and from various vendors.

In 1987, he returned to the university to help organize and head up a new materials science center that later became a university department. This change provided him with new opportunities to collect elements. Eventually, Marshall realized he had pure samples and minerals of most of the elements as well as objects used in commercial applications for each element.

MARSHALL BEGAN to share the wealth of knowledge and materials he had collected. He developed a wall display for the chemistry department, in the shape of a periodic table, in which he included samples of the pure elements and objects made from the elements. The display contains samples of all the elements from hydrogen to uranium that can be handled without special precautions [J. Chem. Educ., 77, 979 (2000)].

He also has been involved with the American Chemical Society's Speaker Service since 1996, traveling to ACS local sections across much of the South and Midwest to speak about the history of the elements and give demonstrations. Marshall has given numerous talks to high schools and community groups as well. He put together a collection of elements in a small portable display to take on these trips.

In addition, Marshall wrote a book, appropriately titled "Discovery of the Elements," which provides a history of the elements written at the high school or introductory college level. He further developed a "Walking Tour of the Elements," available on a CD, which is a virtual tour of the elements. The CD features hundreds of images of elements, minerals, and man-made objects from the collection, along with information from the book.

In a few cases, the Marshalls have had to stretch reality a bit in claiming to have samples of each element in pure form and a sample of each discovery mineral.

For the so-called ancient elements--mercury, lead, copper, iron, and tin--it's not clear who discovered them, Jim Marshall notes. Historical records, though, indicate the region in which each element probably was used first. The Marshalls are taking photos of famous ancient mining sites to include with the collection.

In the complete collection, which is kept in their home, promethium (a radioactive rare earth) is included in the form of a promethium chloride solution. The gases are all held in 1-L globes, with the exception of fluorine, which reacts with the silica in glass. It is represented by fluorite (CaF₂). For the display at the university, empty glass globes tinted yellow and faint green represent fluorine and chlorine; for the traveling exhibit, empty vials stand in for all the gases. Air-sensitive elements, such as alkali metals, are stored under oil.

The couple has samples of all the discovery minerals except fluorite, from which fluorine was discovered. It's known that the discovery fluorite came from an old mine in Sweden, he says, but there are no mineralogical specimens known from this mine, which has long been exhausted and abandoned.

The collection doesn't include pure samples of protactinium, actinium, francium, or astatine. As a substitute, there is a sample of pitchblende, a principal uranium mineral, where at any time there will be a small amount of each of those elements present in the radioactive decay chain. The couple considered trying to collect elements beyond uranium, but federal restrictions on possessing and displaying those elements and the cost made this impractical.

The Marshalls were married in 1998, and the rediscovery project kicked off when they went to Europe on their honeymoon. Jenny Marshall spent 23 years teaching computer science to middle school students in Denton before retiring in May 2003. Her background in computers and photography has turned out to be invaluable to the project, her husband says.

On their first trip, they visited several sites, including Pierre and Marie Curie's lab in Paris, where several elements were discovered; Strontian in Scotland, where strontium was discovered; and an old mine in Romania where tellurium was discovered. "We bit off a lot that first year, but it was exciting," he says. "Then we realized we still had about 80 elements to go."

Since then, the couple has traveled to more than 20 countries in Europe and North America to complete their task. On their most recent trip, in May and June of this year, they found out that Swedish chemist Carl W. Scheele probably discovered oxygen at a pharmacy in Malmö--not in Uppsala, as previously thought. As Jim Marshall points out, Scheele recognized oxygen before Joseph Priestley, although Priestley was first to publish and has generally been credited as the discoverer of oxygen.

One interesting feature of the rediscovery project is the use of the satellite-based Global Positioning System to obtain coordinates for the discovery sites. "This is important in our publications to allow others to find the sites again without having to rely on landmarks such as a house or other building that is gone or trying to find a mine site that is overgrown," he says.

WITH THEIR last trip, the Marshalls believe they have visited all the sites they need to complete the rediscovery project. Now they are left with finishing the literature searches and writing up the story of each element. So far, they have written up more than 20 of the elements, and they have published papers on a few of them.

They are currently exploring potential publishers for the book, and they hope to have it in print by 2006. The CD would include the information in the book and more, as well as some 1,000 photographs. The Marshalls may produce the CDs themselves.

So which element is their favorite? "That's easy," Jim Marshall responds. "For both of us, it's radium."

The reason is that the element "has such a beautiful story behind it," he says. "Pierre and Marie Curie worked hard to discover it. Their work with radium shows what it takes to make a scientific discovery. It's a story about all the hopes, the fears, the aspirations, the disappointments, and the exhilaration and hard work before one finally makes a discovery. It's a very human story."

Radium also has special meaning for the Marshalls, since it was one of the first elements they sought to track down on their rediscovery project. In doing so, they spent a great deal of time exploring and falling in love with Paris. "To us, radium symbolizes what there is to see about Paris," he says. "It taught us that there is always something new to discover."