Assertion: alkaptonuria's urine | /r/CapableOf | expose to the air
Facets:
Source sentences:
text: If the urine of an individual with alkaptonuria is allowed to stand exposed to the air it will gradually turn dark brown-black as a result of the conversion of homogentisic acid to a melanin-like compound.
text: If left to stand and exposed to the air, the urine will oxidise and start to turn black.