Robert Abbe was not the only physician enthusiastic enough about radium to pay top dollar for the precious substance. The tremendous worldwide demand for radium led to the creation of a new mining and medical-products industry. Robert Abbe's papers offer some insight into the global scope of that industry. In December of 1913, Abbe received a sealed tube containing a radium isotope, mesothorium, from Hannover, Germany. In a hand-scrawled note at the top of the page, he noted that the sample remained "still active and apparently as powerful as ten years ago" in 1924, when Abbe tested it with an electroscope in his lab. The Curies' laboratory continued to supply some radium salts to researchers; note Marie Curie's signature at the bottom of the receipt below, received in 1914, on the eve of the First World War. The war significantly disrupted the worldwide radium network, but it proved lucrative for U.S. radium producers. The largest of these was Standard Chemical, based in Pittsburgh, Pennsylvania. Tubes of radium from Standard came with flashy certificates of authenticity, like the one pictured below.