Th: Jefferson returns his thanks to mr Warren, & through him to the President of the Massachusets Medical society, for the copy of their Pharmacopoeia forwarded to him. he sees with pleasure that that society has set the useful example of rendering the language of their science intelligible to us all. he considers too as a valuable step in the reformation of medecine the commencement which has been made in expunging from the Materia Medica the mass of useless articles which has so long encumbered it’s catalogues. he has no doubt this work will render the humane services which the society have so laudably had under contemplation. he salutes mr Warren with respect.