MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Positive test for chlorine. At left, a moist blue litmus paper is held over a test tube of chlorine. At right, the chlorine vapour turns the strip red and then bleaches it white. Blue litmus paper turns red under acidic conditions.
Model release not required. Property release not required.