142 REPORTS ON INVESTIGATIONS AND PROJECTS. 



was removed by long and continued digestion in solutions of caustic 

 potash. The silicon was removed by digestion in hydrofluoric acid. 

 In this manner excellent needle crystals of metallic thorium were 

 obtained which on analysis proved to be 99 per cent pure. 



The metal is steel gray in color, does not change in the air, does 

 not decompose in water, is not affected by cold or boiling water. It is 

 attacked slowly by concentrated nitric and hydrochloric acids ; is 

 attacked readily by dilute hydrofluoric acid, and dissolves readily in 

 dilute hydrochloric acid. At about 200 ° C. it burns in the air to 

 the white oxide. In the finely divided condition it gives brilliant 

 pyrotechnical display when sprinkled in the flame of the Bunsen 

 burner. It burns brightly in a current of oxygen. When heated 

 in ammonia gas it is converted into the hydride. There are appar- 

 ently two stages for this reaction : first, it assumes a beautiful bluish- 

 green iridescent color, and after treatment for five hours becomes 

 a dark brown. The product is not decomposed by water or acids, 

 but by fused caustic alkalies. These bodies will receive further 

 attention. 



The metal is converted into the nitride when heated in an atmos- 

 phere of dry nitrogen. At a low heat the metal combines readily 

 with chlorine, bromine, iodine, and the vapors of sulphur and phos- 

 phorus. The specific gravity of the purest compound obtained was 

 10.95 ; the specific gravity of the regulus was 4, varying with the 

 aluminum present. It is interesting to note that the metal possessed 

 practically the same radioactivity as the ordinary pure thorium oxide. 

 Having prepared 400 grams of this metal, it will be used for further 

 experimentation looking toward the complexity of thorium. A por- 

 tion of it has been utilized by Eberhard and Humphreys in obtaining 

 an accurate spectrum for subsequent comparisons. 



EXTRACTION OF INACTIVE THORIUM. 

 Charles Baskerviele with Stroud Jordan. 



The author and Zerban published (see report to the Carnegie Insti- 

 tution of Washington for 1904) the finding of a very small percentage 

 of inactive thorium in a South American rock. Having secured 150 

 pounds of this material, we have investigated it with great care. We 

 succeeded in obtaining from it about 1 pound of a black mineral, which 

 appears to be new.* We have not determined this definitely, as the 

 complete analysis has not been finished. By a very tedious process 



* Through the courtesy of Dr. W. H. Nichols, president of the General Chem- 

 ical Company, the heavy portion of this work was carried out in one of the 

 factories at Laurel Hill. 



