water]. What a wonderful thing it is to see that it requires so much water as that [a half-pint vessel full] to fall towards the earth, compared with the little mass of substance I have here! And again, if I take this metal [a bar of aluminium[1] about eight times the bulk of the platinum] we find the water will balance that as well as it did the platinum; so that we get even in the very outset, an example of what we want to understand by the words forces or powers.
I have spoken of water, and first of all of its property of falling downwards:—you know very well how the oceans surround the globe—how they fall round the surface, giving roundness to it, clothing it like a garment; but, besides that, there are other properties of water. Here, for instance, is some quicklime, and if I add some water to it, you will find another power or property in the water.[2] It is now very hot, it is steaming up, and I could perhaps light phosphorus or a lucifer-match with it. Now, that could not happen without a force in the water to produce the result; but that force is entirely distinct from its power of falling to the earth. Again, here is another substance [some anhydrous sulphate of copper[3]] which will il-
- ↑ Page 10. Aluminium is 212 times heavier than water.
- ↑ Pages 10 and 11. Power or property in water. This power—the heat by which the water is kept in fluid state, is said, under ordinary circumstances, to be latent or insensible. When, however, the water changes its form, and, by uniting with the lime or sulphate of copper, becomes solid, the heat which retained it in a liquid state is evolved.
- ↑ Page 10. Anhydrous sulphate of copper: sulphate of copper deprived of its water of crystalisation. To obtain it the blue sulphate is calcined in an earthen crucible.
