A process control test for PVC pipe which indicates how well the rigid vinyl compound has been fused together in the extruder. Improperly fused pipe will tend to flake when placed in anhydrous acetone.

A test for ketonuria; the suspected urine is shaken up with a few drops of sodium nitroprusside, and strong ammonia water is then gently poured over the mixture; if acetone is present, a magenta ring forms at the line of contact; tablets containing sodium nitroprusside and alkali are now more commonly used. (05 Mar 2000)