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 flush toilet developed by Sir John Harrington in 1596 for Queen Elizabeth Iâs Richmond Palace has never become commercial. Alexander Cumming developed a water-flushed toilet in 1775 and it was Joseph Bramah, a cabinetmaker in England who patented the first practical toilet in 1778.