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 last antecedent to toilet paper was paper. The Egyptians were the first to discover that papyrus could be made into paper around 2500 B.C. In 105 A.D., a Chinese court official named Cai Lun discovered that paper could be made from trees. The Arabs learned how to make paper from the Chinese in 712 A.D. Spain received this technological innovation during Arab occupation in 1150.