238 Qitirhe and Fhikelstein — Measurements of the 



to sizes between 100 and 200 mesh, and boiled with cone. HCl 

 and HXO3. The acid sohition was filtered, and set aside, and 

 later added to the residue. The residue was fused with 20 gm 

 K,C03, 20 gra JNXCO3, 2 gm ISXB.O,, and 0-5 gm Ba(OH),.* 

 The fused mass was broken up, and dissolved in 200*^"^ water. 

 The sokition was filtered, and the residue added to the acid 

 solution in which the metal portion of the meteorite had been 

 dissolved, and boiled until solution was complete. Sulphuric acid 

 was added to the boiling solution, and the barium sulphate 

 filtered off. The barium was separated from tlie aqueous solu- 

 tion in the same way. The barium sulphate precipitates were 

 combined, and fused with 10 gm KHSO^ in a hard glass test 

 tube. The tube was provided with a rubber stopper fitted 

 with two glass tubes. One of the tubes reached nearly to the 

 bottom of the test tube, and the other just penetrated the 

 stopper. Each tube was bent at right angles to the fusion tube, 

 and the exposed ends which were drawn out to fragile points 

 were sealed. 



The granite and diorite samples were treated in the same 

 ^vay, except that the preliminary treatment with acids was left 

 out. In the treatment of the granite it was found necessary to 

 use hvdrofluoric acid to o^et rid of the silica in the residue. 



Purification of Reagents 



One of the principal sources of error apt to be introduced is 

 the use of reagents which might contain appreciable amounts 

 of radium. This is especially true of the barium salts. Blank 

 tests were made on the reagents used to determine their radium 

 content. Only the barium salts were found to contain enough 

 radium to make the radioactivity of the charge appreciable. It 

 was therefore essential that the barium salts be completely 

 freed from radium. This was done by fractional cijstallization 

 as hydroxides according to the method of McCoyf. The barium 

 chloride was dissolved in a special flask, and a 50 per cent 

 sol. KOH which had been previously freed from carbonates 

 by addition of barium was added. The solution w^as cooled in 

 ice and allowed to crystallize. The mother liquor was filtered 

 off, and discarded. After six crystallizations the barium 

 hydroxide was found to be completely freed from radium. 



* In some preliminary experiments, each of the stony meteorites received 

 from Ward's Natural Science Establishment, and the rock samples, labora- 

 tory numbers 105, 108, 109, and 110, were fused with 0'5 gm of BaCOa in- 

 stead of 5 gm Ba(0H)2. It was found that this brought the radioactivity 

 of the charge up to 0'34 x 10"^- grams of radium element. However, with 

 the use of radium-free Ba (OHja the radioactivity of the charge was found to 

 be imperceptible. 



f U. S. Patent No. 1,103,600 (1914). 



