The word "bismutan" is typically spelled with a single T, even though it may intuitively appear as if it should have two. This spelling is consistent with the International Phonetic Alphabet (IPA) transcription, which identifies the third letter as a voiceless dental stop, similar to the sound produced by pronouncing the word "bit." The presence of a second T may create a different pronunciation, so spellers should be attentive to the correct spelling when encountering the word "bismutan."
Isutan, a yellow insoluble powder said to be a mixture of resorcin and bismuth tannate, employed in diarrhea in doses of gr. 1-5 (0.06-0.3).
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.