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.
1 as saying that âPresident Fillmore installed the first bathtub in the White House, while Boston still had a law against taking a bath without medical advice.â. 2  June 1937 The Akron, Ohio. 3  tells the story of Americaâs first bathtub. 4  1937 Lyndon Brown uses âthe slow acceptance of the bathtubâ as an example in his book. .