On the Operation of Medicines, 1 97 



age between war and poverty, and between con- 

 queft and defolation. 



With great refpeft I have the honour to be 



S I R, 



Your moil obedient humble Servant, 

 llZT',^. BENJAMIN RUSH. 



A Physical Inquiry into the Powers and 

 Operation of MEmfciNES j- by Thomas Per- 

 civAL, M. D. F. R. S. and S. A. Lond. F. R. S. 

 and R. M. S. Edinb. &c. &c. 



Causa latex, vis est notissima. 



Ovid. 



TO THE LITERARY AND PHILOSOPHICAL SOCIETY. 



MANCHESTER, NOVEMBER 25, I786. 



MEDICINES are the inftruments em- 

 ployed for the prefervation of healrh, or 

 the cure of difeafes : It muft, therefore, be an 

 objeft of interefting fpeculation to the philofo- 

 pher, and of pradical importance to the phy- 

 fician to inveftigate the rationale of their asflion 

 on the human body. But there is no branch of 

 O 3 the 



