Chemistry and Physics. 235 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Radio-active Lead. — Those substances that emit the remark- 

 able rays discovered by Becquerel have heretofore been found 

 associated with the uranium, thorium, barium, bismuth and tita- 

 nium extracted from minerals containing uranium and thorium. 

 Hofmann and Strauss have recently found active properties in 

 lead salts obtained from such minerals, viz., pitchblende, cleveite, 

 broggerite, uranium mica, samarskite and euxenite, and they 

 believe that they have evidence of the existence of a new element 

 which resembles lead in many ways, but is quite different from 

 that metal in other respects. The substance, like lead, gives a sul- 

 phide which is insoluble in dilute acids and in ammonium sulphide, 

 and a sulphate insoluble in dilute sulphuric acid. The chloride is 

 more readily soluble than lead chloride in pure water. In the 

 spark spectrum occurs a violet line which does not belong to lead. 

 The equivalent weight of the substance is very different from 

 that of lead, and the valency seems to be higher, since the sul- 

 phate liberates iodine from an acidified solution of potassium 

 iodide. The authors think it probable that the element in ques- 

 tion is bivalent and quadrivalent and has an atomic weight of 

 over 260. The chloride and especially the sulphate fluoresce 

 under the action of cathode rays, and they thus acquire the 

 property of acting upon the photographic plate in the dark. It is 

 only after some months that they lose this activity, which 

 approaches in intensity that of the most active thorium or ura- 

 nium preparations. The present communication is merely a pre- 

 liminary notice, and further publications promised for the near 

 future will be awaited with interest. — Berichte, xxxiv, 8. 



h. l. w. 



2. Physiological Action of Radium Pays. — It has been noticed 

 by Walkhoff that the rays of radio-active barium produce 

 inflammation of the skin, similarly to Rontgen rays. This fact has 

 been confirmed by Giesel. The latter placed a double celluloid 

 capsule containing *27 g. of active barium bromide for two hours 

 in contact with the inner surface of the arm. At first there was 

 only a slight reddening of the skin, but after three or four weeks 

 a severe inflammation set in. Giesel found also that the radium 

 rays exert a similar action upon the leaves of plants ; the chloro- 

 phyl disappears, and the exposed part takes on the yellow or 

 brown color of autumn. — Berichte, xxxiii, 3569. h. l. w. 



3. Chlorine Heptoxide. — This new substance, C1 2 7 , which is 

 the anhydride of perchloric acid, has been prepared by JVJichael 

 and Conn by the action of phosphorus pentoxide upon pure per- 

 chloric aeid. The reaction is a dangerous one on account of the 

 explosive nature of the product, and must be carried out very 

 gradually at a temperature of — 10°. Chlorine heptoxide is a 



