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CARNEGIE INSTITUTION OF WASHINGTON. 



One is disposed to conclude that pure "iso"-lead (assumed to come 

 from the decomposition of uranium and radium) must have an 

 atomic weight very near this last value, and that the Australian 

 "iso"-lead consists of this same substance mixed with about one-third 

 of its weight of ordinary lead. The mixture has not yet been sepa- 

 rated by any means as yet employed. Isotopic lead is clearly very 

 similar to ordinary lead in most of its chemical properties. This 

 research has just been published. 



The following table contains the experimental data and results. 



The atomic weight of isotopic lead. 



2. TuE Density of Isotopic Lead. 



This researcli also was conducted by Dr. Charles Wadsworth 

 3d. The Australian mixture and the Norwegian pure sample just 

 described were reduced to the metallic state and were compared with 

 l)ure ordinary lead prepared in exactly the same way. Parallel 

 determinations gave as the respective densities of the ordinary lead, 

 the Australian mixture, and the pure Norwegian "iso"-lead, the values 

 11.337, 11.289, 11.273. These numbers are very nearly proportional 

 to the atomic weights, "iso"-lead having a density unquestionably less 

 than ordinary lead, and each having almost exactly the same atomic 

 volume, 18.28. The results have already been published. 



3. The Compressicility of Casein and Other Substances of 

 Physiological Importance. 



This subject was studied experimentally by Sven Palitszch (of the 

 Carlsberg Laboratory of Copenhagen, Scandinavian- American scholar) 

 with the help of apparatus already described. Especial attention was 

 given to the comparison of the compressibilities of the solids with 

 those of concentrated solutions and suspensions of the substances 

 concerned. The results will soon be ready for publication. 



