SCIENCE PHOTO LIBRARY SCIENCE PHOTO LIBRARY
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Cold compress. A bag of ammonium nitrate used as a cold compress to reduce minor pain or swelling. Along with the ammonium nitrate is an inner bag containing water. By squeezing the outer bag, the inner bag is ruptured and the water mixes with the nitrate. This is a strongly endothermic reaction, so the temperature of the bag drops.
Model release not required. Property release not required.