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.
While Thomas Crapper is commonly given credit for inventing the first flushing toilet in the late 1800s, the first version can actually be traced back to 1596. At this time, a British nobleman, Sir John Harrington, first engineered and invented a valve that could release water from the water closet (WC) when pulled. Sir Harrington, who was also the godson of Queen Elizabeth I, recommended pulling the valve (âflushingâ the toilet) once a day for sanitary purposes.