82 



Lord Kelvin on 



Table II. 



Comparison of the Temperatures of the Melting-points of Metals 

 afforded by recent research. 



Authority. I 



Date of f 

 publication. \ 



Heycock & 

 Neville. 



1895. 



Holborn & 

 Wien. 



1895. 



Hoi man, Law- 

 rence, & Barr. 



1896. 



D. Berthelot. 

 1898. 



The Author. 



1898. 



Instrument \ 



Resistance 

 Pyrometer. 



Thermo- 

 couple. 



Thermo-couple. 



Interference j Thermo - 

 Method couple no. 11. 



Calibration | 

 data. ; 



0° 

 100° 

 444°-53 



Porcelain air- 

 thermometer. 



0° 444° 53 

 100° 1072° 



218°-2 



Expansion 

 of air. 



0° 

 100° 

 444° -53 



Tin 



2319 



41896 



6545 



960-7 



1061-7 



1080-5 



968 

 1072 

 1082 



660 



970 



(1072) 



1095 



962 

 1064 



2321 

 268-4 

 3259 

 418-2 

 619-2 

 961-5 

 1062-7 

 10830 



Bismuth 



Lead 



Zinc 



Aluminium . 

 Silver 



Gold 



Copper 



V. Contact Electricity of Metals. By Lord Kelvin, 

 G.C.V.O., D.C.L./LL.D., F.R.S., M.B.I * 



§ 1. TTTITHOUT preface two 95 years' old experiments of 

 T T Volta's were, one of them shown, and the other 

 described. The apparatus used consists of: (a) a Volta- 

 condenser of two varnished brass plates, of which the lower 

 plate is insulated in connexion with the gold leaves of a gold- 

 leaf electroscope, and the upper plate is connected by a flexible 

 wire with the sole plate of the instrument ; {b) two circular 

 discs, one of copper and the other of zinc, each polished and 

 unvarnished. I hold one in my right hand by a varnished 

 glass stem attached to it, while on my left hand I hold the 



* Communicated by the Author, having been read at the meeting of 

 the Royal Institution on May 21st, 1897. 



