Letter from Pierre Curie

Curie discusses technical and economic problems of extracting radium, actinium, polonium and radioactive lead in the factory. He mentions suppliers and compares factory methods with small-scale laboratory techniques. Curie states that he and Mme. Curie have perfected a laboratory assay method for radium, using radium emanation from dissolved salts. The letter is probably written to G.D. Liveing.