TRANSFERENCE OF CHEMICAL AFFINITY. 137 



and connect the platinum of one vessel with the 

 zinc of another, the platinum of this vessel 

 with the zinc of that, and so on, we should only 

 be using a series of these vessels instead of one. 

 This we have done in that arrangement which 

 you see behind me. I am using what we call a 

 Grove's voltaic battery, in which one metal is 

 zinc, and the other platinum, and I have as 

 many as forty pairs of these plates all exercising 

 their force at once in sending the whole amount 

 of chemical power there evolved through these 

 wires under the floor and up to these two rods 

 coming through the table. We need do no more 

 than just bring these two ends in contact, when 

 the spark shows us what power is present ; and 

 wh'at a strange thing it is to see that this force 

 is brought away from the battery behind me, 

 and carried along through these wires. I have 

 here an apparatus (fig. 46) which Sir Humphry 

 Davy constructed many years ago, in order to 

 see whether this power from the voltaic battery 

 caused bodies to attract each other in the same 

 manner as the ordinary electricity did. He 

 made it in order to experiment with his large 

 voltaic battery, which was the most powerful 

 then in existence. You see there are in this 



