MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
The cobalt chloride test for water. The blue cobalt chloride test paper is held over a test tube of water. It is important that the paper is stored in low humidity before the test since exposure to 55% relative humidity or greater is sufficient to cause a slow color change.
Model release not required. Property release not required.