JESUITS. BARK. PERU VI AN-B ARK. 151 



-establish its medicinal character, it seems to us greatly inferior to 

 that of the other species of this genus. In its recent state it ii con- 

 siderably emetic and cathartic ; properties, which in some degree 

 it retains on being dried ; so that the stomach does not bear this 

 bark in large doses, and in small ones its effects are not such as to 

 give it any peculiar recommendation. Several plants of Cinchona 

 have lately been discovered at Santa Fe, yielding barks both of the 

 pale and red kind ; and which, from their sensible qualities, are 

 likely upon trial to become equally useful with those produced in 

 the kingdom of Peru." 



At present, the use of the bark is chiefly confined to the pale aad 

 red kind; and the nearer the former resembles the latter, the more 

 it is esteemed. 



" The Peruvian Bark yields its virtues both to cold and boiling 

 water; but the decoction is thicker, gives out its taste more readily, 

 and forms an ink with a chalybeate more suddenly than the fresh 

 cold infusion. This infusion, however, contains at least as much 

 extractive matter, but more in a state of solution ; and ks colour on 

 standing with the chalybeate becomes darker, while that of the de- 

 coction becomes more faint. When they are of a certain age, the 

 addition of a chalybeate renders them green ; and when this is the 

 case, they are found to be in a state of fermentation, and effete. 

 Milk or caustic alkalies, or lime, precipitate the extractive matter, 

 which in the case of the caustic alkali is re-dissolved by a farther 

 addition of the alkali. Lime-water precipitates less from a fresh 

 infusion than from a fresh decoction ; and in the precipitate of this 

 last, some mild earth is perceptible. The 'infusion is by age re- 

 duced to the same state with the fresh decoction, and then they 

 deposit nearly an equal quantity of mild earth and extractive mat- 

 ter; so that lime-water as well as chalybeate, may be used as a 

 test of the relative strength and perishable nature of the diiferent 

 preparations, and of different barks. Accordingly, cold infusions 

 are found by experiments to be less perishable than decoctions ; 

 infusions and decoctions of the red bark, than those of the pale : 

 tho^e of the red bark, however, are found by length of time to 

 separate more mild earth with the lime-water, and more extracted 

 matter. Lime-water as precipitating the extracted matter appears 

 an equally improper and disagreeable menstruum. Water has been 

 found to suspend the resin by means of much less gum than has 



U 



