10$ ON VARIOUS SPECIES OK CINCHONA. 



proved by the history of the first boy in the present Piper, 

 who before the operation had no knowledge of colours or 

 distances, but after it, when his eye had only arrived at the 

 same stare^ that the second boy's was in before the operation* 

 he had learnt that the objects were at a distance, and of dif- 

 ferent colours: that when a child has acquired a new sense* 

 nothing- but great pain or absolute coercion will prevent 

 him from making use of it. 

 Gabraclsin In a practical view, these cases confirm every thing, tiiat 



thildren gene- has been stated by Mr. Pott and Mr. Ware, in proof of ca-> 



hilly soft, and J . . ' 



touching pro taracts in children being generally soft, and in favour of 



ferable to ex- couching, as being the operation best adapted for removing 

 them. They also lead us to a conclusion of no small im- 

 portance, which has not before been adverted to; that, 

 when the cataract has assumed x a fluid form, the capsule, 

 which is naturally a thin transparent membrane, has to resist 

 the pressure of this fluid, which like every other diseased 

 accumulation is liable to increase, and distend it, and there-* 

 fore the capsule is rendered thicker and more opaque in its 

 substance, like the coats of encysted tumours in general. 

 The earlier the As such a change is liable to take place, the earlier the 

 performed the operation is performed in all children, who have cataracts 

 betten. completely formed, the greater is their chance of having 



distinct vision after the Operation. It is unnecessary to point 

 out the advantages to be derived from its being done at a 

 more early age, independent of those respecting the opera- 

 % tion itself. 



VI. 



Experiments on Various Species of Cinikona: by Mr. 

 Vauquelin*. 



fceVeral kinds VO EVERAL different kinds of cinchona are met with in 



of i J r, vian ^ shops, but the chief and most in use are the following 

 bark in the r ' ~ 



?ho;>s three. First that formerly called by the vague nameof Peruvi- 



'ree an b;>rk, and white appears to be taken from the cinchona of* 



iicinahs L. This is externally of a gray colour, and inter- 



thief. 



The common : 



Abridged from the Annates de Chimie, vol. LIX, p. 1 13, Aug. 1306. 



nally 



