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 Abraham Lincoln (1861-65) was credited by the Portsmouth Ohio Times in 1932 to hold the distinction of being the first President of the United States to splash his way to cleanliness in a White House bathtub, the first bathtub having been installed in the White House during his presidency..