M. Beketoff on the Displacement of some Elements by others. 309 





d. 



€. 



-100. 



e 



d 



%/v = r. 



K 



[0-86 



39-2 



22 



45-6 



3-58 



Na 



0-9; 



23 



4-2 



237 



2-87 



Ca; 



1-58 



20 



7-9 



12-6 



2-33 



Mg 



175 



12 



14-6 



70 



1-91 



Al 



2-5 



9 



277 



3-6 



1-53 



— 



— 



13-5 



18-5 



5-4 





Zn 



6-9 



32-6 



21-2 



4-6 



1-66 



Fe 



7-8 



28-0 



27-8 



36 



1-53 



Co 



8<6 



29-5 



291 



3-4 



1-51 



Cd 



8-8 



56 



157 * 



6-5 



1-86 



Cu 



8-9 



317 



28-0 



3-6 



1-53 



— 







63-4 



140 



7-2 



1-93 



Pb 



11-4 



103-5 



11-0 



9-2 



2-09 



Hg 



13-5 



100 



13-5 



73 



1-94 





— 



200 



675 



14-6 



2-45 



Ag 



10-4 



108 



9-6 



10-2 



2-17 



Au 



19-3 



198 



97 



10-2 



217 



Pt 



210 



987 



212 



4-6 



1-66 



In this case d— spec, grav., e= equivalent. 



It is thus seen that almost universally the specifically lighter 

 metal is also the stronger. The further the metals are apart, 

 the more certain is this rule. With elements which are near 

 each other (Sn andPb, Ag and Hg), the reverse of the rule may 

 be the case. With metals of almost equal specific gravity (Ni and 

 Co, Cd and Cu), the mutual replacement is determined with diffi- 

 culty. Copper and lead form a surprising exception : although 

 copper is specifically lighter than lead, yet lead, as is well known, 

 easily displaces copper; but copper scarcely displaces lead. Hg 

 and Ag are scarcely to be considered exceptions : mercury dis- 

 places silver; but, as Odling found, silver can also displace 

 mercury ; and, moreover, mercury is liquid. 



Besides the metals, the rule indicated is confirmed by the 

 cases of CI, Br, and I, and, as far as can be concluded from a 

 few experiments, in the cases of O, S, Se, and Te. 



The author discusses the influence of the specific gravity of 

 the elements on their reactions, and thereby reduces chemical 

 affinity to purely mechanical principles. 



In chemical decompositions the relative stability of different 

 compounds plays an essential part. The author comes to the 

 conclusion that, of the compounds of an element, those are most 

 stable in which the equivalents of the elements united are as nearly 

 equal as possible. Of the silver compounds, for instance, 



AgO (108 : 8 = 13-5 : 1), AgCl (108 : 35*5 = 3 : ]), 



Agl(108: 127 = 1 : 1J-), 

 Phil. Mag. S. 4. Vol. 31. No. 209. April 1866. Y 



