ABSTRACT
Henri Becquercl in early 1896. Unfortunately the discovery came hard on the heels of the announcement of x-rays by 'Nilhelm Rontgen, and Becquerel's rays were greeted as a.'1ticlimactic in the wake of the uproar surrounding those of Rontgen. At the British Association meeting of 1896 in Liverpool, J J Thomson devoted fully five pages in his address to xrays, and scarcely five lines to Becquerel's rays. One reason radioactivity was dismissed as a largely obscure curiosity was feebleness of its photographic in contrast to the startling obtained with x-rays. Moreover, about considered Becquerel rays be a mixture of primary and secondary x-rays of unknown origin [13-1]. This was most definitely the opinion of Rutherford, who announced in his seminal paper of 1899 that the rays of uranium and its salts consist of at least two components: a-rays (the 'secondary' rays), that are readily absorbed in matter (and ionize a gas rather well),. and (primary) rays of much greater penetrating power which are less effective ionizers).
