While all forms of matter may be changed or modified they can never be destroyed. As an illustration, when sugar dissolves in water the particles of sugar are so small or so minutely divided that they cannot be seen. Yet they are not destroyed because they can be recovered by boiling the water until it disappears in the form of steam and leaves the particles of sugar behind. Or, if wood or coal is burned and the ashes, vapors, and gases that have come from it are collected and separated from the gases of the air with which they have united during the process of combustion, it will be found that the united mass of the ash, gases, and vapors is the same as the mass of the original piece of wood or coal. It is a fundamental principle of science that matter is indestructible.