PARIS, John Ayrton. PHARMACOLOGIA OR THE HISTORY OF MEDICINAL SUBSTANCES WITH A VIEW TO ESTABLISH THE ART OF PRESCRIBING AND OF COMPOSING EXTEMPORANEOUS FORMULAE UPON FIXED AND SCIENTIFIC PRINCIPLES. London: W. Phillips, 1820.  Fourth edition, much enlarged.  578 pp.  Quarto.  Original paper-covered boards with old repair work to spine: a "new" cloth back was laid down some time ago to reattach the boards.  Hand-lettered spine labels.  Ex-Library, with ink-stamps to front endpaper and page 50. Text leaves are lightly foxed throughout and untrimmed.  Good plus.