COHESION 43 



glass globe, which immediately became filled with the violet 

 vapor], and you see the same kind of change produced. 

 Moreover, it gives us the opportunity of observing how beau- 

 tiful is the violet-colored vapor from this black substance, or 

 rather the mixture of the vapor with air (for I would not 

 wish you to understand that this globe is entirely filled with 

 the vapor of iodine). 



If I had taken mercury and converted it into vapor (as 

 I could easily do), I should have a perfectly colorless vapor; 

 for you must understand this about vapors, that bodies in 

 what we call the vaporous or the gaseous state are always 

 perfectly transparent, never cloudy or smoky; they are, 

 however, often colored, and we can frequently have colored 

 vapors or gases produced by colorless particles themselves 

 mixing together, as in this case [the lecturer here inverted 

 a glass cylinder full of binoxide of nitrogen ( 15 ) over a 

 cylinder of oxygen, when the dark red vapor of hyponitrous 

 acid was produced]. Here also you see a very excellent 

 illustration of the effect of a power of nature which we 

 have not as yet come to, but which stands next on our list 

 CHEMICAL AFFINITY. And thus you see we can have a 

 violet vapor or an orange vapor, and different other kinds 

 of vapor, but they are always perfectly transparent, or else 

 they would cease to be vapors. 



I am now going to lead you a step beyond this considera- 

 tion of the attraction of the particles for each other. You 

 see we have come to understand that, if we take water as 

 an illustration, whether it be ice, or water, or steam, it 

 is always to be considered by us as water. Well, now pre- 

 pare 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 obtaining light, and which we carried 



15 Binoxide of nitrogen and hyponitrous acid. Binoxide of nitrogen is 

 formed when nitrio acid and a little water are added to some copper 

 turnings. It produces deep red fumes as soon as it comes in contact with 

 the air, by combining with the oxygen of the latter to form hyponitrous 

 acid. Binoxide of nitrogen is composed of two parts of oxygen and one 

 part of nitrogen; hyponitrous acid is composed of one part of nitrogen and 

 three parts of oxygen. 



