382 UNSUSPECTED RADIATIONS. 



which thoy come into contact. The o-old leaflets of a charged electro 

 scope dro[) at the contact with them.' Rut Hec«|uci-(>1 was not satisfied 

 with mei"cly statin^:' this tact: lie iimncdiatclv dcxised a very delicate 

 instruinent for measuiinii- the activity of ditlerent rays e-iven up by 

 various l)odies. P(n"hai)s he did not realize that he was thus endowing 

 .science with a new method of analysis, which would lead, like spec- 

 trum analysis, to the discovery of new elements; but in the hands of 

 M. Curie and Madame Sklodowska-Curie this method really led to 

 the discovery of at least one element, radium, and perhaps two more — 

 polonium and actinium. 



From the very outset it ])ecam(> evident that compounds of uranium, 

 and especially the metjil itself, prepared in a pure stiite b^^ Moissan, in 

 his electric furnace, were possessed of the greatest radio-actiAMty. 

 Thoriiun. with its compounds, came next. As to th(> other elements, 

 nearly all of which were examined by Mme. Sklodowska, they were 

 all much inferior to these two. It was also noticed during these 

 researches that, as a rule, the compounds were inferior to the pure 

 metals thenjselves. One miniM'al. however, the Bohemian pit<'hblende, 

 as also two others of less importance — all compounds of uranium — 

 proved to be nmch more radio-active than pure uraniuu) itself, and M. 

 and Mme. CUirie, suspecting that the pit<'hblende must contain some 

 new substaiice more active than uranium, ])egan a most painstaking 

 laboratory work in order to isolate that special substance. They 

 obtained at last a metal identical as to its chemical properti<>s with 

 bisnmth. l)ut far more radio-active, and they named it polonium, in 

 honor of Madame Sklodowska's fatherland. Then, begimiing once 

 more, in company with (t. Bemont, the whole research from the 

 beginning, in order to hunt for another very radio-active su])stance of 

 which they had suspected the existence, they obtained another metal 

 similar to l)ariuin ])y its chemical properties. Imt still more radio- 

 active, which they named radium." And finalh', A. Debierne has dis- 

 covered lately, by the same method, a third element named actinium 

 and chemically similar to titanium.'' Mr. Crookes, while disagreeing 

 with the Curies as regards their new elements, came also, after a long 

 research, to some new element, or at least to some new Aariety of 

 uranium, which he named ""UrX,'' and which in his opinion is neither 

 polonium nor radium.* The new method of '"radiation analysis" had 

 thus completed its proofs. 



Of course, so long as these new elements have not been separated 



^ Ttiis fundamental property of the Becquerel rays was announced on the very 

 same day by Becquerel at Paris (Comptes Rendus, 1897, Vol. CXXIV, j). 438), and 

 by Lord Kelvin, J. C. Beattie, and Sinoluchowski Smolan at Edinburgh, l)efore the 

 Edinburgh Royal Society (Natiire, 1897, Vol. XLV, p. 447). 



■^Comptes Rendus, 1899, Vol. CXXVII, p. 1215. 



•Ubid., 1900, Vol. CXXX, p. 906. 



*Proceednigs of the Royal Society, tlie 10th ..f May, 1900. 



