Why is
that? Obviously, because the molecules have got a little further apart.
If you heat it till the iron gets liquid, the liquid would also occupy
still more space than the original solid rod; and if we had temperature
high enough to make the melted iron go off into vapour, it would occupy
an enormously increased space. I cannot say what it would be for iron
vapour; but if a given volume of water is converted into vapour, it will
occupy about 1,700 times the space it did when liquid, though the weight
would not be altered.
It may here be worth while to mention that it is not invariably true
that a substance gets contracted, and the molecules more and more
pressed together, as it assumes a solid form. There is at least one
exception. If we take 1,700 pints of steam, the water, as I said, on
becoming cool enough to lose the vapourous form, will shrink into a
measure holding a single pint; if we cooled lower still, it will get
smaller and smaller in bulk (though of course not at all at the same
rate) till it arrives at a point when it is just going to freeze; then
suddenly (7 degrees above the freezing point) it again begins to expand.
Ice occupies more space than cold water; its molecules get arranged in a
particular manner by their crystallization.
On the admission of an _intelligent_ Creator providing, by beneficent
design, the laws of matter, it is easy to give a reason for this useful
property.
Pages:
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47