ON VARIOUS SPECIES OF CINCHONA. 21 1 



In the first may be comprise:! those, that precipitate tan- T f h ^ dasses 

 nin, and do not precipitate animal glue. 



In the second, those that precipitate animal glue, and do 

 not precipitate tannin. 



In the third, those that precipitate both tannin and animal 

 glue, and also tartarised antimony. 



2. (Ve may conjecture with sufficient probability, that Indication of 

 every vegetable substance, which does not possess at least one f ebnfuge pro- 

 of the properties above mentioned, will not be a febrifuge; 



and it is probable too, that the more these properties unite in 

 a cinchona, or in any other substance, the more striking will 

 be its febrifuge effects. 



3. The property of precipitating tannin not being com- 

 mon to all the cinchonas, it is not from this exclusively, that 

 they derive their febrifuge virtue; for there are several that 

 do not precipitate it, and yet cure intermittent fevers. 



4. It appears however, that the principle which precipi- 

 tates infusion of oak bark and nutgalls is febrifuge, for the spe- 

 cies that produce this effect are generally allowed to be the 

 best for medicinal use. 



5. On the other hand, since cinchonas which precipitate These not con- 

 • i • r ■ <> lii c » c , fined to one 



neither infusion of tan nor nutgalls are febrifuge, we must principle. 



conclude, that the principle, by which these precipitations 

 are produced, is not the only one in cinchona, that cures 

 fever. 



6. The principle that precipitates infusion of - tan and Principle that 

 nutgalls has a brown colour, and a bitter taste; it is less so- tar ^ 



luble- in water -than in alcohol; it precipitates likewise tar- 

 tarised antimony, but not isinglass. It has some analogy 

 with resinous substances, though it affords ammonia by dis- 

 tillation. 



7. It is apparently with the tannin of oak bark and nut- Doubts, 

 galls, that this principle combines to form the. precipitates it 

 occasions in the infusions of these substances: yet, as this 

 principle exists in some species of cinchona, that precipitate 

 isinglass at the same time, it remains questionable, whether it 

 actually combine with the tannin of the infusion of oak bark, 



or whether the principle, that in other species of cinchona 

 precipitates isinglass, be real tannin. 



P 2 ft. But 



