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470 PROCEEDINGS OF THE AMERICAN ACADEMY. 



a convenient and exceptionally thorough means of purifying caesium 

 material. 



4. No evidence was found indicating the presence of any similar ele- 

 ment of higher atomic weight, except a trace of thallium. 



5. The specific gravities of caesic chloride, hromide, and nitrate were 

 found to be respectively 3.972, 4.380, and 3.687 ; and the melting point 

 of the nitrate was found to be 414° C. 



6. The precautions necessary to effect the precisely cmantitative de- 

 composition of alkaline nitrates are described. 



Cambridge, Mass. 

 October, 1900, to November, 1902. 



