A 



JOURNAL 



OF 



I^ATURAL PHILOSOPHY, CHEMISTRY, 



AND 



THE ARTS. 



DECEMBER, 1803. 



ARTICLE L 



X<?««fr//'o>/i Andrew Duncan, M.D. F.R.S.E. contain- 

 ing Expfirimtnts and ObJ'efmtions on Cinchona, tending parti^. 

 culurh/ to JJieiv that it does not contain Gelatine i ' ' ■• "; 



To Mr. NICHOLSON. 

 SIR, • 



JrlAViNG been long engaged in a ferres of expjerimehts oh . 

 the aftringent fubftances employed in medicine, I was parti- 

 cularly interefted with the " Abftrad of a Memoir on the Fe- 

 brifuge principle of Cinchona," contained in the laft number 

 of your CKcellent journal. The prefence of gelatine in cin-Prefenceof gc« 



chona, was ,fo incompatible with experiments I had formerly,'^^'"'^ '" '^'"- 

 'i 1 '" T " o , • 1- . 1 .- 1 , r. . chona, amif- 



jmnde, that J was ftrongly inchned to believe, that, begum take, 



(than whom no one fliould be better acquainted with the com- 

 binations of tannin and gelatine) had been mifled, either from 

 having examined cinchona which had been adulterated, or 

 from fome other accidental caufe. To fatisfy myfelf I imme-' 

 diately proceeded to the unerring teft of experiment, which 

 has convinced methat cinchona does nof contain gelatine, but But It contain* 

 fome other principle not yet fufficiently examined, which/°""^ "'^^^■'P"'^- 



"...., .,,,-.. ^ . . , . . . ciiile, forming 



agrees With geiatme, m formmg with tannm, a precipitate an jnfoiuble pre- 

 comparatively infoluble in water. At the fame time it is but cipitate withi 

 feir to remark, that my experiments were made with the in- 

 VoL. VI. — December. Q fufion 



