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.
[BBC News âThe origin of ice-creamâ; Wikipedia âIce creamâ]. The first documented use of toilet paper dates back to the 6th century in China. However, it was only produced for use by the Imperial Court. Records show that by the early 14th century, millions of packages were being mass-produced in China annually.