JBoltwood — Ionium, a New Radio-active Element. 375 



After correcting the activities for the amounts of thorium and 

 thorium products present, it was found that the amount of 

 radium produced in each solution was quite closely propor- 

 tional to the activity of the other material present. From 

 these results it appeared highly probable that the substance 

 from which radium was produced was an element emitting an 

 a radiation. To further test the properties of the active sub- 

 stance the following experiments were performed. Some 

 thorium had been separated from a quantity of uraninite about 

 six months before and had been carefully purified by the well 

 known method of dissolving the oxalate in an excess of 

 ammonium oxalate. The oxalate had been later ignited at a low 

 beat to form the oxide. The activity of this oxide was high and 

 it contained an amount of the new body having an activity 

 about equal to that of five grams of pure uranium. The oxide, 

 weighing 0'4 gram, was placed in a glass tube between plugs of 

 cotton wool, and a strong current of air was drawn through the 

 tube and into a sensitive electroscope. The only emanation 

 which could be detected was that due to thorium. 



The greater part of solution 3, described above, was then 

 taken, diluted to a volume of about 800 oc and, after heating to 

 boiling, an excess of ammonia was added. The hydroxides 

 were filtered oft: and the residue obtained on evaporating the 

 filtrate to dryness was examined. The activity of this residue 

 was slight and appeared to be due entirely to thorium X. 

 The hydroxides were dissolved in an excess of hydrochloric 

 acid and a small quantity of sodium thiosulphate was added. 

 The solution was boiled and the separated sulphur was filtered 

 ■off. It was ignited and the activity of the very slight residue 

 was tested and found to be one one-thousandth of that 

 of the total active material in the solution. Some sulphuric 

 acid followed by barium chloride was added to the solution 

 and the precipitate of barium sulphate which formed was 

 removed. The activity of this was tested and was found to be 

 less than the activity of the residue left from the sulphur. It 

 was evident that the active substance in the solution was not 

 actinium, for if it had been the treatment with ammonia would 

 have separated actinium X*, and the treatment with sodium 

 thiosulphate and barium sulphate would have separated radio- 

 actinium, t 



A more active preparation of the new substance was then 

 obtained in the following manner: To the solution procured 

 by treating about one kilogram of carnotite ore with dilute 

 hydrochloric acid there was added a few milligrams of thorium 



* Giesel, Ber. d. chein. Ges., xxxYiii, 775,1905; Godlewski, Phil. Mag.. 

 x, 35, 1905. 

 f Hahn, Phil. Mag., xiii, 165, 1907. 



