Sloane's patients were primarily from the middle and upper classes, coming from across the British Isles and, on occasion, Europe. Although he was not known for being an innovator, he was respected for his careful observations and willingness to use new remedies once they proved helpful. He prescribed, for example, quinine (distilled from Peruvian Bark), invested in it heavily and wrote about it for the Philosophical Transactions. He was also instrumental in the adoption of smallpox inoculation in England, using it on his own family and successfully encouraging its use for the Royal Family. Sloane has also been widely linked to the promotion of milk chocolate as a remedy.