A hydrometer is an instrument used to determine specific gravity. It operates based on the Archimedes principle that a solid body displaces its own weight within a liquid in which it floats. Hydrometers can be divided into two general classes: liquids heavier than water and liquids lighter than water.
The belief was that there was a distinct order of living things: Chinese, barbarians, and beasts. That's why they made all foreign diplomats bow down to the Emperor and why they completely isolated the country to show that it's self sufficient.
