823 



the purity of the material experimented on and as there often 

 exists some uncertainty concerning the method whereby the density 

 has been determined. 



4. Kahi.baum, Roth and Siedlkr ^) found the density of a pure 



20° 

 specimen of lead prepared by distillation in vacuo to be r/ -^ 11.34J. 



5. The values given by different authors for the specific heat of 

 lead vary within wide limits, as may be seen from the table given 

 in Abegg's Handbuch der anorganischen Chemie.^) Moreover it may 

 be called to mind that Le Verrier') stated, that the specific heat 

 of lead is a function of its previous thermal history. 



6. The facts mentioned above as well as the investigations of 

 Stoiba, *) and those of Otto Lehmann *) render a new investigation 

 of the subject very desirable. 



7. A year ago we carried out some experiments in this direction. 

 As the results were negative we experimented with other metals, 

 which yielded a more favourable result. Since a fresh investigation 

 on lead has given positive results, as will be proved below, we 

 give here also a short description of our earlier experiments, which 

 taken together with the new experiments furnish a confirmation of 

 the results obtained by us in the case of other metals (bismuth, cad- 

 mium, copper, zinc, antimony). 



8. Our experiments have been carried out with lead which 

 contained only 0.001 per cent of copper and 0.0006 per cent of 

 iron (Blei-"KAHLBAUM"-Berlin). ") 



The metal was turned into shavings on a lathe and washed with 

 dilute nitric acid, water, alcohol and ether. After this it was dried 

 in vacuo over sulphuric acid. 



9. The density of this material was found to be 



25° 

 d —- a. 11.328« 



b. 11.330, 



We put the metal into an aqueous solution of PbCl, and kept it 

 for 48 hours at 100°. After washing and drying it, we found : 



1) Zeitschr. f anorg. Chemie 29, 177 (1902). 



2) Bd. 3, 2le Abteilung, p. 633 (Leipzig 1909). 



3) Gomp. Ernst Cohen, Proceedings 17, 200 (1914). 



4) Journ. f. prakt. Chemie 94, 113 (1865): 96, 178 (1865). 



5) Zeitschrift f. Kristallographie und Mineralogie 17, 274 (1890). 



Ernst Cohen and Katsuji Inouyi, Zeitschr. f. pliysik. Chemie 74, 202 (1910). 



6) MvLius, Zeitschr. f. anorg. Chemie 74, 407 (1912), 



