William S. N. Allan was a family physician and dispensing chemist at the Apothecaries' Hall, Washington Square, Newport in 1863. Prior to this he was a clerk for Hazard & Caswell, Wholesale & Retail Druggists.

Allan dealt in fancy goods, soaps, perfumes, and combs and brushes as well as Congress and Empire Waters. He manufactured a toothpaste called, an 'elegant' tooth powder named ODONTINES, a tooth wash called EXCELSIOR, and an EXTRACT OF JAMAICA GINGER for flaticience and dyspepsia. Allan also produced CITRATE OF MAGNESIA and various flavoring extracts.

Circa 1867, he became a pharmaceutist, filling out physicians' prescriptions. He was now located at 18 Washington Square, Newport, a shop which had been established by Charles Feke in 1780. By 1885, Allan was operating as a druggist from his home located at 37 Sherman Street in Newport. Allan passed away in 1886.