The original manuscript of the Declaration of Independence being carried into the NBS Chemistry Building on August 22, 1951. The Declaration of Independence and the U. S. Constitution were brought to NBS to be sealed in helium-filled glass enclosures to protect them against decay and insect damage. The process started on August 22 and continued for a month while pure helium gas was allowed to flow through each enclosure for two weeks, totally displacing the inside air.
National Institute of Standards and Technology
National Institute of Standards and Technology