Ultrasonic humidifiers are the quietest humidifiers available, and the ideal choice when noise level is a concern (if you are a light sleeper). In general, a warm moisture humidifier will be much quieter than a cool moisture evaporative humidifier.
Iodine is a chemical element with symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a lustrous, purple-black metallic solid at a standard conditions that sublimes readily to form a violet gas. The elemental form was discovered by the French chemist Bernard Courtois in 1811.
Sublimation is another one of these phase transitions; except in this case, we have a solid turning directly into a gas. As a sublimating material changes from a solid to a gas, it never passes through the liquid state. This image shows water in its three forms: ice, water, and steam. Sublimation is just one of the ways water or another substance can change between its potential phases.