Though the title suggests tropical medicine in general, this work mainly concerns the selection and medical care of slaves. Digital facsimile of the second edition (Edinburgh, 1802) expanded "with practical notes and a Linnean index") from the Internet Archive at this link.

"Grainger first travelled to the West Indies in 1759 as a companion to a former patient. While there he married Miss Burt whose uncle Daniel Mathew owned estates and enslaved people in St Kitts, Tobago and Antigua. Grainger managed Mathew's St Kitts' estates as well as practising as a physician. Although he never owned an estate, Grainger is reported to have bought enslaved people" (https://history.rcplondon.ac.uk/inspiring-physicians/james-grainger).