Chemistry and Physics. 453 



SCIENTIFIC INTELLIGENCE 



I. Chemistry and Physics. 



1. Researches on Polonium. — This was the first of the new and 

 strongly radio-active bodies to be discovered, but it has not yet 

 been isolated and characterized as a chemical element. Accord- 

 ing to the theory of radio-active transformation the relative 

 proportions of the products are equal to the ratio of their mean 

 lives, and since polonium is regarded as a descendant of radium, 

 which has a life about 5300 times as long, a ton of pitchblende 

 containing about 0-2 g. of radium could contain only about "04 mg. 

 of polonium. Since polonium apparently represents the last 

 unstable body in the series derived from radium, it may be 

 expected that polonium will produce an inactive element, which 

 has been supposed to be lead, and a verification of this transforma- 

 tion would be an important support to the theory. Mdme. Cukie 

 and A. Debierne have recently undertaken a chemical research 

 with the view of preparing polonium in a concentrated state. 

 They employed several tons of residues from the uranium mineral, 

 first treating it with warm hydrochloric acid, which dissolved the 

 polonium almost completely. The solution which contained no 

 radium was submitted in a factory to a series of operations, the 

 details of which are reserved for future description, and which 

 yielded about 200 g. of a substance having a mean activity about 

 3500 times that of uranium, and containing chiefly copper, bis- 

 muth, uranium, lead and arsenic. This material was then treated 

 in the laboratory by various chemical methods in order to con- 

 centrate the polonium. Precipitation with hydrogen sulphide in 

 acid and alkaline solution and precipitation by stannous chloride 

 were found to be the most trustworthy reactions for the sub- 

 stance. When the product was reduced to a few milligrams it 

 was found by spectrum analysis to contain mercury, silver, tin, 

 gold, palladium, rhodium, platinum, lead, zinc, barium, calcium 

 and aluminium. Great difficulties were encountered in attempt- 

 ing to make a further concentration, but it was found that polo- 

 nium can be deposited completely by electrolysis from an acid 

 solution, although other metals, such as gold, platinum, mercury, 

 etc., are deposited at the same time. After many experiments 

 the activity was concentrated in about 2 mg. of matter. From 

 the activity of this product it was calculated that it contained 

 about 0'1 mg. of polonium. A portion of it was sacrificed for 

 the study of the spark-spectrum, and several lines were obtained 

 which may be attributed reasonably to polonium. The authors 

 propose to examine the spectrum lines again after the polonium 

 has disappeared, in order to make certain of the lines belonging 

 to it. They hope to see also the spectrum of the element formed 

 at the expense of polonium, which, according to theory, should be 



Am. Joub. Sci.— Fourth Series, Vol. XXXI, No. 185. — May, 1911. 

 31 



