Producible by Attrition and Contact of Metals. 17 



the galvanometer ; and the second with the silver side ; and if the two metals, 

 at the same temperature, be rubbed against each other, the deflection will in all 

 cases be west of tlie magnetic meridian. 



2. If the first-named metal, being on the zinc side, be adequately and equally 

 heated throughout its mass, while the second, on the silver side, is adequately 

 cooled, either contact or attrition will cause eastern deflection. 



3. If the first-named metal on the zinc side be adequately cooled, and tlie 

 second on the silver side be adequately heated, either contact or attrition will 

 cause western deflection. 



4. The converse of the foregoing propositions is, that if the second-named 

 metal be connected with the zinc side of the galvanometer, and the first with 

 the silver side, attrition against each other, provided they are at the same tem- 

 perature, will cause eastern deflection. 



5. If the second-named metal on the zinc side be heated, and the first on 

 the silver side be cold, either contact or attrition will cause eastern deflection. 



6. And if the second-named metal on the zmc side be cold, and the first 

 on the silver side be heated, contact or attrition will cause western deflection. 



From this arrangement of metals and effects, we can deduce the results of 

 attrition and thermo-contact of any particular pair, mentioned in the foregoing 

 list, by the aid of the following paradigm. Let bismuth and antimony be taken 

 as the representatives of any other pair placed in the same order in relation 

 to each other as in the foregoing list. 



A. Bismuth on the zinc side, antimony on the silver side. 



1. The attrition of the two metals when at the same temperature will give 

 western deflection. 



2. When the bismuth is hot and the antimony cold, either contact or attri- 

 tion will give eastern deflection. 



3. When the bismuth is cold and the antimony hot, either contact or attri- 

 tion will give western deflection. 



B. Antimony on the zinc side, bismuth on the silver side. 



4. Attrition of the metals when at the same temperature, will give eastern 

 deflection. 



5. When the antimony is hot and the bismuth cold, contact or attrition 

 will cause eastern deflection. 



VOL. XXHI. D 



