During the following three years Ramsay worked on his most significant An Essay on the Treatment and Conversion of African Slaves in the British Sugar Colonies,[3] published in 1784. It was this essay which influenced Beilby Porteus, Bishop of Chester and later Bishop of London, in his campaign to improve the conditions of slaves held by the Society for the Propagation of the Gospel in Foreign Parts, as well as bringing to public notice the debate about the slave trade. He contributed several further publications to the campaign, including An Inquiry into the Effects of Putting a Stop to the African Slave Trade, published 1784.