756 



NUMERICAL CONSTANTS. 



Electromotive Forces of Contact, in volts at 23, deduced from 

 the Peltier Effect* 



Copper | Antimonyf -0*0151 



,, ,, commercial o"OOc6 



,, Iron - 0-0029 



,, Cadmium -0*00053 



,, Zinc -0*00045 



,, Argentan +0*00287 



,, Bismuth, pure +0*0222 



,, % +0*0300 



Iron | Zinc, at 13*8 +o*oo25 



Copper | Sulphate of Copper, at 12 + 0*212 1| 



Zinc | Sulphate of Zinc, at 12 +0*241 



These numbers are very different from those which have been 

 obtained by electrostatic measurements. 



ELECTROMOTIVE FORCES OF THE PRINCIPAL LIQUID ELEMENTS. 



Standard Elements at 7"5.U 



Zinc 



Saturated solution of Sulphate of Zinc . 

 Sir W.Thomson. . Semi-saturated solution of Sulphate of 1*074 



Copper 



Copper 



Zinc 



Latimer Clark**. . Sulphate of Zinc . . 



Sulphate of Mercury in paste . 

 Mercury 



Voltatt 



Ordinary Couples. 



Zinc 



Ordinary Water . 

 Copper 



* LE Roux. Ann. de Chim. et de Pliys. [4], Vol. x., p. 248. 1867. 



t Alloy containing I eq. of antimony, I eq. of cadmium, and \ of the total 

 weight of cadmium. 



% i o bismuth + i antimony. 



BELLATI. Atti del R. I. V. [5], Vol. v. 1879. 



|| BOUTY. Journal de Physique, Vol. ix., p. 229. 1880. 



IT Lord RAYLEIGH. Phil. Trans., 1884, pt. ii., p. 459. 



** The electromotive force diminishes as the temperature increases. The 

 variation for i is 0*00082 according to Lord Rayleigh, and 0*000781 according 

 to M. Pellat. 



ff The electromotive force is at first feeble, and attains the constant value 

 0*98 after some time. The same result is at once arrived at by adding to the 

 liquid a little sulphate of zinc. 



