Originally posted by not_important
I would suspect phosphoric acid added the the H2SO4 in the drain opener, as a corrosion retardant.
You could try putting a few ml of the residue in a test tube and heating near 500 C. Cool, add water , wash the test tube into a flask and gentle
boil for some time, then test for phosphate and lead. The test tube likely would be etched if it's a phosphate heated that hot, or if it's lead
sulfate; a good reason to test before using up expensive glassware. |