force, anil t! >us forms of Thermo-batteries and 



i no-couples that have been used, tried, or cxpcrinv 

 with, and arc a in history , I may just say that the 



experiments that are here selected for description have all 

 been made with soft Iron for the first couple, and Xinc- 

 untimony for the second. Many other metals and different 

 substances have been tried during a series of some few 

 thousands of experiments ; but to simplify the argument 

 and to clear the ground, I shall only mention a few 

 cxpcr and confine them to these two metals, which 



were chiefly used. 



In making any desired couple, it was clearly necessary to 

 sec that the Iron was clean ; that exactly the same quantity 

 and proportion of Zinc and Antimony were used, and cast 



arly as possible under the same conditions ; t 

 perfect joint was made in casting, so that the Iron and 

 antimony were one body. Otherwise many false n 



! have been registered ; and I may mention that all 

 the results described have been tested at least four, and the 

 than a dozen t; 



cct to test any conclusion in this 

 juotc several experiments that have been 



. and in about the same order in which they actually 

 took place. Without this it will be impossible cither to 



in or u : 1 what actions really go on, though 



ultimately these will lead up to, and throw some light upon 

 the point we arc trying to prove. 



In the Thermo-couples, we used a Hunsen gas 



! iii i IH T to produce the heat, and a piece of sheet iron of 

 convenient shajn upon non-conducting supper 



supply t to the couples; the usual wires being 



connected by binding screws to the couples, or lea 



. or to the ^alvanoc md a 



tluTiiuu: < es of heat J*"i& l). 



.U- the 'ivity of Silver at 100 , that 



