1894.] 



Presents. 



81 



Applying this constant in the well-known formula, the following is 

 found to be the specific resistance at C. : 



<T O O C . 1559-1 C.G-.S. units. 



Table of General Results. 



C.G-.S. 

 units. 

 Specific resistance of A. deposit 



(hard) At C. = 1603 



Same wire after annealing in CO 2 At C. = 1566 

 Specific resistance of Sample B 



(annealed) At C. = 1559 



Temp, co- 

 efficient 

 At. 



0-00408 

 0-00418 



0-00415 



As the difference between the last two values only amounts to 

 0*4 per cent., it is probable that both of the specimens were perfectly 

 pure, and that the limit of electrolytic purification had been reached. 

 The mean of the two gives the probable specific resistance of pure 

 copper. Thus, as a general conclusion, it may be stated that the 

 specific resistance for pure copper (hard and annealed) is : 



Hard variety, wire 1603 C.G-.S. units and A, = 0'00408. 

 Soft 1563 = 0-00416. 



Presents, May 24, 1894. 

 Transactions. 



Baltimore : Johns Hopkins University. Circulars. Vol. XIII. 

 No. 111. 4to. Baltimore 1894; Studies in Historical and 

 Political Science. Series XII. No*4. 8vo. Baltimore 1894. 



The University. 



Breslau : Schlesische Gesellschaft fur Vaterlandische Cultur. 

 Jahres-Bericht. Bd. LXX. 8vo. Breslau 1893. 



The Society. 



Calcutta : Indian Museum. Notes. Vol. II. No. 7. 8vo. Cal- 

 cutta 1893. The Museum. 



Dublin : Royal Dublin Society. Scientific Transactions. Vol. 

 IV. Part 14. Vol. V. Parts 14. 4to. Dublin 1892-93 ; 

 Scientific Proceedings. Vol. VII. Part 5. Vol. VIII. 

 Parts 12. 8vo. Dublin 1892-93. The Society. 



Frankfort-on-the-Main : Senckenbergische Naturforschende Ge- 

 sellschaft. Abhandlungen. Bd. XVIII. Heft 2. 4to. 

 Frankfurt a. M. 1894. The Society. 



Gottingen : Konigl. Gesellschaft der Wissenschaften. Nachrich- 

 ten. 1894. No. 1. 8vo. Gottingen. The Society. 



VOL. LVI. G 



