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.
Despite these ancient beginnings, flush toilets as we know them today are a much more recent invention. The inventor of the modern flush toilet is generally considered to be Sir John Harrington, who invented a flush toilet in 1596. Harrington's toilet included a flush valve that would release water from a tank to wash away waste in the bowl.