Page:On the various forces of nature and their relations to each other.djvu/90

86 always perfectly transparent, never cloudy or smoky: they are, however, often coloured, and we can frequently have coloured vapours or gases produced by colourless particles themselves mixing together, as in this case [the Lecturer here inverted a glass cylinder full of binoxide of nitrogen over a cylinder of oxygen, when the dark-red vapour 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—. 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 transparent, 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 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 prepare your minds to go a little deeper into the subject. We have means of searching into the constitution of water beyond any that