For a long time he was held in vague esteem for the success of his cooling (or rather expectant) treatment of smallpox, for his laudanum (the first form of a tincture of opium), and for his advocacy of the use of "Peruvian bark" in quartan agues, in modern terms, the use of quinine-containing cinchona bark for treatment of malaria caused by "Plasmodium malariae".