👉 A hygroscope is a type of microscope used to observe and study samples that have been dried, frozen or in other forms. It consists of a thin, flat glass slide with a small hole cut into it at one end, which allows light to pass through. The slide is then placed on a holder called a "hygrometer," which is typically made of an aluminum plate. As the sample dries and cools, the water in the air inside the hygrometer condenses onto