4^6 Mr. W. R. Grove on the Influence of 



It is very probable that the Chinese have had the same kind 

 of alloys in use for perhaps more than two thousand years ; it 

 was of interest, therefore, to compare the composition of some 

 ancient Koman coins with that of Chinese coins. I have been 

 permitted by the Rev. H. S. Osbornj for whom I have made 

 analyses of coins of the emperors Hadrian and Trajan, for his 

 work on 'Palestine, Past and Present,^ to insert these in this paper. 

 No. 9. Hadrian Coin. — Of a bronze-yellow colour ; the colour 

 on the fresh fracture is inclining to brass-yellow ; grain very fine. 

 Spec. grav. =8-778. It contains — 



Copper = 8692 per cent. 



Sdver = 0-30 



Tin = 0-72 



Lead = 110 



Zinc = 10-97 



Iron . . . . . . . — 0'18 „ 



Arsenic and Antimony . = traces 



100-19 

 No. 10. Trajan Coin. — The colour is bronze-yellow, inclining 

 to brass-yellow ; the fresh fracture is greyish ; very fine grain. 

 Spec. grav. =8-745. It contains — 



Copper = 88-58 per cent. 



Silver = 0-21 



Tin = 1-80 „ 



Lead = 2-28 



Zinc = 7*56 ., 



Iron = 0-29 „ 



100-72 



Both coins were stamped, and not cast like those from China ; 

 and both were pretty tough, which is certainly owing to the 

 smaller per-centage of zinc and iron in the same. These alloys 

 were beyond question made directly from the ore, and only the 

 small per-centage of tin appears to have been added afterwards. 



XLIX. On the Influence of Light on the Polarized Electrode. 

 By W. R. Gkove Esq., Q.C., V.P.R.S. S^c*. 



SOON after the experiments of Daguerre were published, it 

 occurred to me that the galvanometer might be used as a 

 test for the chemical effects of light ; and I succeeded in obtaining 

 a deflection of the needle by allowing a beam of light suddenly 

 to impinge on a daguerreotype plate in a trough of water — the 



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

 the British Association, Leeds, September, 1858. 



