368 Boltioood — Ionium, a New Radio-active Element. 



ated, a conclusion which was not justified, as was shown later 

 by the work of Dadourian, McCoy, Eve, and Bolt wood. 



These excerpts from the literature have been given because 

 the} 7 have an interesting bearing on the experiments, which 

 will now be described. 



Early Experiments. 



In the spring of 1899, Mr. Clifford Langley, one of my 

 students in the Sheffield Scientific School, with which I was at 

 that time connected, undertook to repeat under my direction 

 the interesting experiments of M. and Mme. Curie on the 

 separation from pitchblende of the active substances polonium 

 and radium. The work was carried out with about thirty 

 grams of pitchblende, and the products separated were tested 

 for radio-activity in a sheet metal box containing an insulated 

 electrode connected with a quadrant electrometer. Precip- 

 itates containing polonium and radium were obtained without 

 difficulty, but on applying the radio-active test to the material 

 from which these substances had been separated we found that 

 the activity of this was apparently greater than was to be ex- 

 pected for the uranium only. After the removal of the ura- 

 nium by treatment with ammonium sulphide and ammonium 

 carbonate, a small residue remained which proved to be highly 

 active. From a hydrochloric acid solution of this residue the 

 active material was not removed by further treatment with 

 hydrogen sulphide and was not precipitated when the solution 

 was treated with sulphuric acid. On adding an excess of 

 ammonia, a precipitate consisting chiefly of ferric hydroxide 

 wasformed. The total active substance present was separated 

 with this precipitate. 



The main conclusion reached from these experiments was 

 stated as follows in a thesis presented by Mr. Langley as a 

 candidate for honors in chemistry in June, 1899 : " This 

 investigation shows the possibility of the presence of another 

 active element not precipitated by hydrogen sulphide or by 

 sulphuric acid, but which is precipitated by ammonium sul- 

 phide and ammonium hydroxide, thus differing from polonium 

 and radium." 



Owing to various causes the work was not continued further, 

 until after the announcement by Debierne, in the following 

 October, of the discovery of a new radio-active element which 

 was separated with the iron group and which had chemical 

 properties similar to those of thorium. I then found that the 

 active substance which we had obtained was almost completely 

 precipitated from a dilute hydrochloric acid solution on the 

 addition of an excess of oxalic acid. Further experiments 



