1863.] 473 



For M. Lamy's first specimen, 



2nd wire at 0. 3rd wire. 



\=9*419-0-039520+0-00009656* 2 ; 9-082; 9'223. 



Second specimen, 



2nd wire at 0. 

 \ = 9-054-0-034697*+0-00006554* 2 ; 9*226 ; 



or as mean of all the determinations, some of which are not given 

 here, 



The conducting power of thallium therefore decreases between 

 and 100 31-420 per cent., which is a larger percentage decre- 

 ment than that obtained for many other pure metals, namely 29*307 

 per cent.* 



Iron. The specimens of iron experimented were, with two excep- 

 tions, lent us by Dr. Percy. In the following Table we give the results 

 obtained with them : 



(1.) Electrotype iron, deposited from solution of pure sulphate of 

 iron. The strips were very thin and porous ; we could not 

 therefore obtain concordant values for the conducting power, 

 but we were able to determine the percentage decrement in the 

 conducting power between and 1 00. We have, for the above 

 reason, taken the first observed conducting power equal 100. 



X= 100-0-51 182J+0-0012915* 2 , 

 corresponding to a percentage decrement of 38'262 per cent. 



(2.) No. 1, annealed and cooled in hydrogen. 



corresponding to a percentage decrement of 38*479 per cent. 



(3.) Electrotype iron, a strip cut from the same foil as No. 1. 



\= 100-0-51355^ + 0-001322 H 2 , 

 corresponding to a percentage decrement of 38*134 per cent. 



(4.) No. 3, annealed in air. 



X= 100-0-50895^ + 0-0002735^, 



corresponding to a percentage decrement of 38-160 per cent. 

 (5.) This, as well as Nos. 6, 7, 8, were specimens of iron which have 



been analysed. They were all hard drawn. 



corresponding to a percentage decrement of 36'070 per cent. 

 * Phil. Trans. 1862, Part I. 



