“Induced Radioactivity.”
Project Gutenberg EPUB3 edition
H. Stanley Redgrove
§ 91. Radium salts have the property of causing surrounding objects to become temporally radioactive. This “induced radioactivity,” as it may be called, is found to be due to the emanation, which is itself radioactive (it emits α-rays only), and is decomposed into minute traces of solid radioactive deposits. By examining the rate of decay of the activity of the deposit, it has been found that it is undergoing a series of sub-atomic changes, the products being termed Radium A, B, C, &c. It has been proved that all the β- and γ-rays emitted by radium salts are really due to certain of these secondary products. Radium F is thought to be identical with Polonium (§ 87). Another product is also obtained by these decompositions, with which we shall deal later (§ 94).