Dear Mr. Adams,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located 26 record series in the Records of the Chemical Warfare Service (Record Group 175) that cover the 1910s and 1920s. We also located 3 record series from the 1910s and 2 record series from the 1920s that specifically mention mustard gas in their Catalog description. Furthermore, we searched the records of the American Expeditionary Forces (Record Group 120) for “gas” and located 17 series, 673 file units, and 1 item. A search for Record Group 120 for “chemical warfare” located 8 series, 1 file unit, and 1 item. Finally, a search of all Catalog descriptions covering 1910 through 1919 for “chemical warfare” turned up 55 series, 99 file units, and 1510 items. Some of the records from these searches have been digitized and can be viewed online. We also located records relating to the Treaty of Versailles, which condemned the use of mustard gas.
The Center for Legislative Archives preserves and makes available to researchers the historical records of the U.S. House of Representatives and the U.S. Senate. They do not have the personal or office papers of individual members of congress. They can be contacted via email at firstname.lastname@example.org.
The Library of Congress has custody of the Woodrow Wilson Papers. The Library of Congress runs the Veterans History Project that collects oral histories and other materials concerning American veterans of war, including World War I.
You may also wish to research the 1925 Geneva Protocol that condemned the use of mustard gas.
There are also numerous secondary sources concerning chemical warfare during World War I, and some of these have bibliographies that may suggest further resources for research.
We hope this information is helpful. Best of luck with your research!