In late June 1800, Samuel Hodgdon wrote to Israel Wheelen ordering him to fumigate the public stores in Philadelphia. The objective was not only to kill insects but mainly to prevent contagion; summer was the usual time for outbreaks of yellow fever and fumigation was believed to help stop the spread of disease.
Hodgdon recommended that Wheelen use nitre or brimstone (sulfur) for the fumigation. In 1795 the British had carried out a successful experiment on the hospital ship Union using a combination of concentrated vitriolic acid and nitrate of potash (sulfuric acid and potassium nitrate), conducting twice daily fumigation to prevent the spread of a fever. Brimstone, or sulfur, had been used to clear diseased air from ships since the 1750s, and vinegar was also supposed to help clear the air of infection. The prevailing medical theory of the time held that diseases spread through the air in a cloud, or miasma; therefore clearing or treating the air would reduce the risk of disease transmission.
As a side benefit, the combination of gas from the nitrate or sulfur and the liberal application of vinegar afterwards might well have kept bugs away from the stores. That may have been what Hodgdon meant when he referred to the “preservation of the woolen goods.” Even if the practice of fumigation did nothing to prevent the spread of diseases, it at least had some benefit when it came to insects and other pests.
For more on fumigation and the Union experiment, see the entry on Contagion in Encycopaedia or Dictionary of Arts, Sciences, and Miscellaneous Literature (Philadelphia: Printed by Budd and Bartran for Thomas Dobson, 1803).