72 CHEMICAL AFFINITY. 



which we haye not as yet come to, but which 

 stands next on our list CHEMICAL AFFINITY. 

 And thus you see we can have a violet vapour 

 or an orange vapour, and different other kinds 

 of vapour, but they are always perfectly trans- 

 parent, or else they would cease to be vapours. 

 I am now going to lead you a step beyond 

 this consideration of the attraction of the par- 

 ticles for each other. You see we have come to 

 understand that, if we take water as an illustra- 

 tion, whether it be ice, or water, or steam, it is 

 always to be considered by us as water. Well, 

 now prepare your minds to go a little deeper 

 into the subject. We have means of searching 

 into the constitution of water beyond any that 

 are afforded us by the action of heat, and 

 among these one of the most important is that 

 force which we call voltaic electricity, which we 

 used at our last meeting for the purpose of ob- 

 taining light, and which we carried about the 

 room by means of these wires. This force is 

 produced by the battery behind me, to which 

 however I will not now refer more particularly; 

 before we have done we shall know more about 

 this battery, but it must grow up in our know- 

 ledge as we proceed. Now here (Jig. 24) is a 



