336 Prof. McCoy and Dr. Yiol : Chemical Properties and 



it produces. The amount of Msi obtainable from amounts 

 of thorium nitrate at our command (2 to 3 kilos) was small ; 

 we have obtained a large quantity of Ms x from another source. 

 Through the courtesy of Mr. George P. Gilman, of the 

 Lindsay Light Co., Chicago, to whom we wish here to 

 express our sincere thanks, we obtained about 5 kilos of 

 residues left from the refining of several thousand kilos of 

 thorium. After the separation of the thorium salts from 

 cerium &c. by the well-known carbonate process, and the 

 ignition of the residue to remove organic dirt, there remained 

 about 300 g. of material, of which the principal consti- 

 tuents were oxides of the rare earths, silicates, and about 

 10 per cent, of barium sulphate. The barium was separated 

 completely by the following process. The powder was mixed 

 with five parts by weight of an equimolecular mixture of dry 

 sodium and potassium carbonates, and fused in portions at a 

 red heat in iron crucibles. The melt was ground up, treated 

 with hot water, and washed free from sulphate. The residue 

 was dissolved in pure hydrochloric acid and the barium in 

 the filtrate precipitated by sulphuric acid. The barium 

 sulphate yielded 35 g. of nearly chemically pure barium 

 chloride which contained all of the Ms x of the original 

 material. After a few days the gamma-ray activity of this 

 barium chloride was equal to that of 1*5 mg. of pure 

 radium chloride. The Ms x preparation then contained the 

 equilibrium amount of Ms 2 , and also Rt and its products in 

 continually increasing amounts. The activity of the Rt 

 formed per day was about ten times the uranium standard *. 

 Mesothorium-tico. — We separated Ms 2 and Rt from the 

 M.Si solution by adding 2 c.c. of a 5 per cent, aluminium 

 chloride solution and passing in pure ammonia gas. The 

 small precipitate of aluminium hydroxide carried down all 

 of the Ms 2 , Rt, B, and C, together with a small amount of 

 barium carbonate, owing to exposure to the air in filtering. 

 The barium, of course, contained some Ms x and ThX. Radio- 

 actively pure Ms 2 was prepared by dissolving the alumina in 

 acid, making the solution nearly neutral and removing Rt 

 by means of thorium, precipitated by means of hydrogen 

 peroxide, the Ms 2 being left in the filtrate. The alumina 

 was then precipitated with ammonia two or three times to 

 free it from barium, ThX, and Ms! ; finally, B and C were 

 removed by means of mercuric sulphide. The details of 

 these processes will be found under the reactions of the 

 respective radio-products. The emanation, A, and D, which 



* About 38 sq. cm. of a thick film of U 3 C>8. See McCoy & Ashman, 

 Le Badium, v. p. 362 (1908) ; Amer. Jour. Sci. xxvi. p. 521 (1908). 



