Four Years, Eight Tons: Radium Isolation and Persistent Chemistry

0.1 Grams from 8 Tons

The pitchblende arrived from Jáchymov in residue form—eight tons of ore already stripped of its commercially valuable uranium, discarded as waste. Yet my measurements showed this waste more radioactive than pure uranium itself. The conclusion was inescapable: an unknown element, present in minute quantities, must be responsible. But recognizing its existence and isolating it were entirely different problems.

Radium and barium share the same column in the periodic table—both alkaline earth metals with identical charge, similar size, nearly indistinguishable chemistry. Every precipitation, every acid treatment, every solvent extraction brought both elements down together. The only difference: a slight variation in solubility. Radium chloride dissolves marginally less readily than barium chloride in water. This infinitesimal difference—perhaps one part in a hundred at each step—became the entire basis for separation.

Fractional crystallization exploits this narrow gap. Dissolve the mixed chlorides, evaporate slowly, collect the first crystals that form. These contain slightly more radium. Redissolve, repeat. Each cycle enriches the sample by a tiny fraction—an enrichment factor of perhaps 1.001 to 1.01 per iteration. To achieve pure radium from ore containing one part in a hundred million requires hundreds of such cycles. The mathematics are straightforward; the labor is not.

Four Years in a Leaky Shed

We worked in a converted dissection room with a leaking roof and no ventilation. The process demanded enormous batches—twenty kilograms of solution at a time, heated in vats, stirred for hours with an iron rod as tall as I am. No assistants. Pierre helped evenings after his professorship duties. Minimal funding meant using personal finances, eventually selling prize medals to continue.

Each fractional crystallization required precise attention: dissolve ore in acid, precipitate the barium-radium fraction, crystallize, measure radioactivity in each sub-fraction to track the enrichment, select the most active portion, repeat. The measurements guided everything—activity increasing cycle by cycle confirmed we were concentrating the unknown element, not chasing experimental error. Backbreaking physical work: stirring boiling liquid for hours, transferring heavy vessels, lifting containers without mechanical assistance.

Yet this methodical repetition—what some might view as tedious—I experienced as disciplined seeing. Like observing every stamen, every petal of a sunflower, the repeated crystallizations revealed patterns invisible to casual inspection. Each cycle was a question asked of nature; each measurement, nature’s answer. The discipline was not to tire of asking.

Persistence Through Poison

We handled radium compounds bare-handed. Radiation hazards were unknown—indeed, our work was revealing them for the first time. Clothes became contaminated, skin developed burns, we breathed radioactive dust daily. The beautiful blue-green glow in the dark, the warmth radiating from the concentrated sample—these aesthetic wonders masked biological devastation occurring at the atomic level.

After four years: 0.1 gram of pure radium chloride from eight tons of ore. White crystals emitting that characteristic glow. Measured atomic weight 226, matching theoretical predictions. Spectroscopic lines confirmed a new element definitively. The concentration factor: eighty million to one.

The process embodied an alchemical principle: solve et coagula—dissolve and rebind. Each crystallization dissolved rigid mineral structures, examined their hidden contents through radioactivity measurements, then reformed them at higher purity. Not dissolution into chaos, but methodical reformation guided by empirical evidence. Hundreds of cycles, each dissolving and rebinding at incrementally higher order.

Why persist through such difficulty? The question itself reveals a misunderstanding. There was no “decision” to persist in the conventional sense—rather, each measurement showed progress, each crystallization brought us closer to isolation, each data point confirmed the hypothesis. The path revealed itself step by systematic step. To abandon the work would have required abandoning the logic of the evidence itself.

The 1911 Nobel Prize in Chemistry cited “services to the advancement of chemistry by the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element.” The isolation—those four years of fractional crystallization—received equal recognition with the initial discovery. The methodical work mattered as much as the insight.