As we returned to the laboratory I remarked that the quantity of radium in the various tubes I had seen was very small.
"Of course it is small," he sighed; "there is very little radium in the world. I mean very little that has been taken from the earth and purified."
He thought a moment. "We have about one gramme (one-third of an ounce) in France, Germany may have one gramme, America has less than one gramme, and the rest of the world may perhaps have half a gramme. Four grammes in all would be an outside estimate; you could heap it all in a tablespoon."
I suggested to M. Curie the possibility that some philanthropist might be inspired on reading his words to help the new cause. And I remarked that great things could doubtless be accomplished with some substantial quantity of radium, say a pound or two.
He gave me an amused look and asked if I had any idea what a pound or two of radium, say a kilogramme (two and one-fifth pounds), would cost.
"Why, no," said I, "no exact idea; but----"
"A kilogramme of radium would cost"--he figured rapidly on a sheet of paper--"with the very cheapest methods that we have of purifying the crude material it would cost about ten million francs (£400,000). Under existing conditions radium is worth about three thousand times its weight in pure gold."
"And yet there may be tons of it in the earth?"
M. Curie was not so sure of this. "It is doubtful," said he, "if there is very much radium in the earth, and what there is is so thinly scattered in the surrounding ore--mere traces of radium for tons of worthless rock--that the cost of extracting it is almost prohibitive. You will realize this when you visit our works at Ivry."
These works I visited the next day, and found myself outside the walls of Paris, near the old Ivry Cemetery, where some unpretentious sheds serve for this important business of radium extraction. One of the head men met me and explained, step by step, how they obtain this strange and elusive metal. First he showed me a lumpy reddish powder, sacks of it, brought from Bohemia by the ton, and constituting the raw material from which the radium is extracted. This powder is the refuse from uranium mines at Jachimsthal; that is, what remains of the original uranite ore, _pitchblende_, after the uranium has been removed. For years this refuse was regarded as worthless, and was left to accumulate in heaps, tons of it, quite at the disposal of whoever chose to cart it away. Now that it is known to contain the rarest, and most precious substance in the world, it goes without saying that the owners have begun to put a price on it.