Letter, R. W. Raymond to William Van Slooten - Regarding the Practicability of Mining Sulfur from the Calcasieu Deposit (After naming and considering several types of technology, the Poetsch Process which uses freezing. Van Slooten was a principal in the Diamond Prospecting Company, an earlier unsuccessful attempt to mine this sulfur.), 1886

Letter, R. W. Raymond to William Van Slooten - Regarding the Practicability of Mining Sulfur from the Calcasieu Deposit (After naming and considering several types of technology, the Poetsch Process which uses freezing. Van Slooten was a principal in the Diamond Prospecting Company, an earlier unsuccessful attempt to mine this sulfur.), 1886, Box: 2, Folder: 5. Tiers-Frasch Collection, 00-31. Science History Institute Archives. https://sciencehistory.libraryhost.com/repositories/3/archival_objects/43323 Accessed November 24, 2024.