For example, for the Gases under pressure hazard class, the hazard categories are Compressed gas, Liquefied gas, Refrigerated liquefied gas and Dissolved gas. These classes relate to the physical state of the gas when packaged and do not describe the degree of hazard.
1 In 1596, a flush toilet was invented and built for Queen Elizabeth I by her Godson, Sir John Harrington. 2  The first patent for the flushing toilet was issued to Alexander Cummings in 1775. 3  During the 1800s, people realized that poor sanitary conditions caused diseases.
The first âofficialâ toilet paper was introduced in China in 1391, but the first mention of toilet paper (paper for personal hygiene) dates back to the year 589 AD in Korea. Between 875 and 1317 AD, paper was produced in large sheets (2-foot x 3-foot sheets and even perfumed) for Chinese emperorâs family hygiene.