from the spirit lamp is now being consumed, not in making the ether any warmer, but in converting it into vapour, and if I desired to catch this vapour and condense it (as I could without much difficulty), I should have to do the same as if I wished to convert steam into water and water into ice: in either case it would be necessary to increase the attraction of the particles, by cold or otherwise. So largely is the bulk occupied by the particles increased by giving them this diminished attraction, that if I were to take a portion of water a cubic inch in bulk (A, fig. 23) I should produce a volume of steam of that size B [1700 cubic inches; nearly a cubic foot], so greatly is the attraction of cohesion diminished by heat; and yet it still remains water. You can easily imagine the consequences which are due to this change in volume by heat—the mighty powers of steam and the tremendous explosions which are sometimes produced by this force of water. I want you now to see another experiment which will perhaps give you a better illustration of the bulk occupied by a body when in the state of vapour. Here is a substance which we call iodine, and I am about to submit this solid body to the same
