Chemistry and Physics. 303 



SCIENTIFIC INTELLIGENCE. 



I. Chemistky and Physics. 



1. Radio-active Bismuth. — Polonium, the radio-active sub- 

 stance occurring with bismuth in pitchblende, was the first of 

 these substances discovered (by Mr. and Mrs. Curie). Subse- 

 quent investigations by Giesel led the latter to believe that 

 polonium was nothing more than bismuth made active by induc- 

 tion. Marckw^ald, however, has recently obtained results which 

 indicate that polonium is a distinct element. From a by-product 

 obtained from pitchblende, by the usual methods, bismuth oxy- 

 chloride was prepared which was strongly radio-active, and 

 which showed no decrease in activity after several months. 

 Upon subjecting a solution of this substance to electrolysis, it 

 was found that the metal which was deposited at first displayed 

 much greater activity than the final product. This result led to 

 the attempt to precipitate polonium, from hydrochloric acid solu- 

 tions of the oxychloride, by means of a polished stick of metallic 

 bismuth. As a result, the metal became coated immediately with 

 a fine black deposit, which gradually increased, and when it had 

 been removed from the solution and washed, it showed a surpris- 

 ingly strong effect on the electroscope. At the distance of a 

 decimeter the leaves of the charged electroscope collapsed in a 

 moment, and even a gutta-percha rod which had been well rubbed 

 with fur was immediately discharged upon the approach of the 

 bismuth stick. The important fact was noticed that metallic 

 bismuth is thus able to remove practically all of the active 

 material from a solution. The powder could be scraped from 

 the bismuth rod, and the amount thus obtained from 8^ of bis- 

 muth oxychloride was about 5™?. From this result it was calcu- 

 lated that a ton of pitchblende would contain not more than one 

 gram of the substance. The powder was found not to be a pure 

 metal, but to contain some chlorine. Upon heating, a small por- 

 tion volatilized, probably as chloride, and the residue fused to a 

 white, exceedingly brittle, metallic bead. This was soluble in 

 nitric acid, and the solution, as far as it could be tested, gave 

 reactions for bismuth. The salts are as strongly active as the 

 metal, and the rays are characteristically different from those of 

 radium in being unable to penetrate any intervening substance. 

 Even a piece of filter-paper wrapped around a stick of bismuth 

 coated with the active metal causes it to lose all its effect. The 

 experiments are to be continued with larger quantities of material, 

 and it is hoped that an atomic weight determination may be 

 made. — Berichte, xxxv, 365. h. l. w. 



2. A Thermochemical Constant. — F. W. Claeke, in a pre- 

 liminary paper, has made a generalization from a consideration 

 of Thomsen's work on the heats of combustion of certain organic 

 compounds. In the first place, he has re-calculated Thomsen's 



