https://creativecommons.org/publicdomain/zero/1.0/https://www.rawpixel.com/image/14009501Edit ImageSaveSaveEditCropCustom TextProcess of refining of saltpetre and the instruments used. Etching by Bénard after L.J. Goussier.Original public domain image from Wellcome CollectionMorePublic DomainFree CC0 image for Personal and Business useInfoView CC0 LicenseJPEGSmall JPEG 729 x 1200 px | 300 dpiLarge JPEG 1250 x 2058 px | 300 dpiFree DownloadProcess of refining of saltpetre and the instruments used. Etching by Bénard after L.J. Goussier.More