 Parker often preached to the patients, and trained several Chinese students in the arts of medicine and surgery, some of whom attained considerable skill.Merchant David Olyphant of Olyphant & Co. allowed Parker to use one of his warehouses as a hospital "so that patients could come and go without annoying foreigners by passing through their "hongs", or excite the observations of natives by being seen to resort to a foreigner's house, rendered it most suitable for the purpose.