https://www.usa.gov/copyrighted-government-workshttps://www.rawpixel.com/image/3325628Edit ImageSaveSaveEditCropCustom TextOperator carefully mixes coolant for addition to cold trap in an all glass vacuum system in which gases evolved from crystals irradiated by ultra-violet light from lamp (lower left) are measured, c. 1967. Original public domain image from FlickrMorePublic DomainFree CCO U.S. Government image for Personal and Business useInfoView CC0 LicenseEditorial use only JPEGSmall JPEG 1200 x 968 px | 300 dpiLarge JPEG 3004 x 2422 px | 300 dpiFree DownloadOperator carefully mixes coolant for addition to cold trap in an all glass vacuum system in which gases evolved from crystals irradiated by ultra-violet light from lamp (lower left) are measured, c. 1967. Original public domain image from FlickrMore