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.
Although Harington installed a working model for Queen Elizabeth at Richmond Palace, it took several centuriesâand the Industrial Revolutionâs improvements in manufacturing and waste disposal â for the flush toilet to catch on. In 1775 English inventor Alexander Cumming was granted the first patent for a flush toilet. His greatest innovation was the S-shaped pipe below the bowl that used water to create a seal preventing sewer gas from entering through the toilet. In the late-19th century, a London plumbing impresario named Thomas Crapper manufactured one of the first widely successful lines of flush toilets. Crapper did not invent the toilet, but he did develop the ballcock, an improved tank-filling mechanism still used in toilets today.