When a tiled area was found next to the downstream brick floor we thought it was a pathway, but about two weeks later when one of the tiles was lifted it was found to be a brick lined trench about 40cm deep, filled with soil and tiled over. At the bottom was about 5cm of white powdery substance which we thought might be fat removed from bones, so we did a simple test. A small amount was put in a tin and heated with a lighter to see if it would melt. It did not melt so we assumed it was bonemeal and decided to have it tested professionally. This was kindly carried out by Mark Law of Law Fertilisers. As the pictured report shows, the material is processed single super phosphate fertiliser. This means that sulphuric acid was used on site to make fertiliser.
Pieces of glass jars were found buried, and these would have been used for storing sulphuric acid. We found bottle tops with embossed lettering in front of the water wheel and large pieces of thick glass which were the bottom, sides and top of the large bottles.
Lots of pieces of bone have also been found at many places on site, some of which look as if they have been cut, probably with a bandsaw to make them small enough to be processed. All these finds confirm that fertiliser was made here from bones and its good to find so much evidence to support what we already know about the site.