Troy weight them Holland troy, Paris troy, etc. Their values varied from one another by up to several percentage points. Troy weights were first used in England in the 15th century, and were made official for gold and silver in 1527. The British Imperial system of weights and measures (also known as Imperial units) was established in 1824, prior to which the troy weight system was a subset of pre-Imperial English units. The troy ounce in use today is essentially the same as the British Imperial troy ounce (1824–1971), adopted as an official weight standard for United States coinage by Act of
Reuse of excreta Black Soldier Fly larvae with feces. The mature flies would then be a source of protein to be included in the production of feed for chickens in South Africa. It is known that additions of fecal matter up to 20% by dried weight in clay bricks does not make a significant functional difference to bricks. A Japanese sewage treatment facility extracts precious metals from sewage sludge. This idea was also tested by the US Geological Survey (USGS) which found that the sewage sludge generated by 1 million people contained 13 million dollars worth of precious metals. Debate is ongoing about