SCIENTIFIC NEWS, |37 



Hitherto the fight and tafte have been the only tefts of the Sight and taft^ 

 prefumable qualities of the peruvian bark of the (hops ; but as !" j"^"^^"^° 

 thefe l)ave no precife ftandard, and are ijiapplicable to goodnefsof bark,. - 

 powdered bark, they very imperfectly indicate the prefence 

 of the febrifuge principle. Ii vvas of importance, therefore, 

 to fubftitiile to thefe means, little better than illufory, others 

 not only capable of calculation, but likevvife invariable. Che- 

 mical re-agents ^lone can anfwer thefe ends. 



In confequence Cit. Seguin began by ilolating the refpeflive 

 properties of all medicinal fubtiances, and he examined the 

 aflipn they exert on all other chemical fubftances. 



Thefe refearches led him to develope very decifive chara61er» The febrifuge 

 cftics in the febrifuge principle of cinchona ; which place it P'^'ncipje of barfs 

 in a perfectly diftinft clafs. The following are its charaClers. 



It precipitates the folulion of lan, but not the folutions of Its charafters. 

 gelatine and fulphate of iron. 



When cinchona has not all thefe charadlers, it is a proof 

 that it is mixed with fomethiiig elfe, or that it does not contain 

 the febrifuge principle. 



The author has fubjeCled to this analyfis all the known Various fpeci- 

 fpecies of cinchona, found among all the druggifts and apothe- "biefted toxhxi 

 caries of Paris and Ver failles, and conftantly obtained the left, 

 fame refults. 



Unfortunately thefe refearches have Ihown, that but an ^.^'^'^ P''''"'.^'* 



.,-.,/- 11 • r I -1-1 • 1 ^^^^ ^^'y i'tt'« 



infinitely tmall quantity or good, unmixed cinchona, is to be good is to be 

 procured in the (hops ; the greater part being either deftitute^o"n«l '" the 

 of the febrifuge principle, or mixed, or of a very inferior 

 quality, though containing no mixture. 



Thefe refults are of fo much the greater importance, be- Efficacy of cln- 

 cau(e the effects of different kinds of cinchona in fevers are tionate to the" 

 only in proportion to the greater or lefs quantity of the febri- quantity of fe- 

 fuge principle they contain ; and thofe which contain none, as jt'contain'sT'^ 

 well as all the fubfiances that may be mixed with them, are 

 more or lefs injurious to the fydera. 



The experiments of Cit. Seguin on the febrifuge principle Defefts of the 

 of cinchona, having convinced him that moft of the bark found ^j^g fliops, 

 in the fiiop^i was injurious or inefficacious, becaufe it was fpoiled 

 by keeping, adulterated by mixture, or deprived of the febri- 

 fuge principle ; he has endeavoured to obtain a febrifuge prin- 

 ciple always the fame, more efficacious, more certain in its 

 effefts, more capable of affirailation with our fyftera, and fo 

 fcheap, that there could be no temptation to adulterate it. 



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