158 AN EXPERIMENTAL STUDY OF RADIO-ACTIVE SUBSTANCES. 



iiiduccd activity iiicasuivd 1 to 50 times that of uranium; the substances 

 exaiiiiiied were zinc, ahimijuun, brass foil, h^ad, platiiuun, bismuth, 

 nickel, paper, barium carbonate, and bismuth sultid. Her experiments 

 showed that a true induction of radiant ener^}^ is effected, and the 

 eneio-y imparted to metallic plates is not removed by washinu- with 

 water, althouo-h the radium chlorid ('"chlorure dc barimn raditeic"") 

 is soluble. The activity induced by Becquerel rays persists while 

 that caused by Rontgen rays ceases suddenly on removal of the ayent. 

 (C. R. 129, 714, November ♦>. 1899.) 



The actinic power of the rays is shown by exposinj»' the salts to 

 sensiti\e plates; with the relatively pure material obtained by Madame 

 Curie an exposure of one-half minute sufKced to get an impression. 

 The peculiar power of ROntgen rays is seen by using a barium-platino- 

 cyanid fluoroscope, the rays exciting fluorescence through alumiiuun, 

 vulcanite, etc. (C. R. 12<j, IKtl. 189S; (J. R. 127, 1215, DecemlxM- 26, 

 1898.) 



^ladame Curie rec-ords ()l)taining good •* i)lioto-inipr(>s,si()iis" with 

 uranium, uranousoxid, ])iti-hl)len(le.clialc(dite, etc., through glass, air, 

 and aluminum. 



The spontaneous huninosity of radium compomids Avas announced by 

 Madame Curie to the Physical Society of Paris in :\Iarch, 1899 (Rev. 

 chim. pure et appliquee, July. 1899), and in November of that year 

 she published her discovery that the wonderful rays exert chemical 

 action. They transform oxygen into ozone. This was tirst noticed by 

 the odor of the air in a flask in which radium compounds were confint'd, 

 and was confirmed by the usual test witii potassium iodid starch paper. 

 The rays also produce a certain coloration in glass, changing it to violet; 

 and the}' transform barium platino-cyanid from yellow to brown, in 

 which state it is less fluorescent, but this can l)e revived by insolation. 

 (C. R. 129, 828, November 30, 1899.) 



At the suggestion of Madame and Monsieur Curie, Monsieur A. 

 Debierne, working in the laboratory of the Sorbonne, examined pitch- 

 blende for other radio-active bodies, especially the portion precipitated 

 from solution by ammonia and ammonium sulfid, after separafion of 

 the uranium. In October, 1899, he found associated with titanium a 

 substance exhibiting 100,000 times more radiant power than uranium, 

 and having chemical properties distinct from radium and polonium. 

 The rays emitted by this bod}'-, named actinium, have the same mani- 

 fold action as the other substances, with the exception that it is not 

 self-luminous. (C. R. 129, 593, 1899.) 



In a more recent paper (C. R. 130, April 12, 1900) Monsieur Debierne 

 finds that actinium is allied to thorium, and suggests that the radio- 

 activity^ of the latter is due to admixture of the new substance. 



To complete this review of the radio-active bodies, brief notice must 



