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.
In 1937 the Bendix Corporation introduced the world's first automatic washing machine and the lives of housewives was made easier from that day on. Alva J. Fisher invented the first electric washing machine in 1908. It was called the Thor and was manufactured by the Hurley Machine Company in Chicago.