392 Proceedings of the Academe/ at Paris. 



to that of grey quinquina ; the quinine does not difter from 

 that of the yellow bark, except by the slightest shades in its 

 properties. Another remarkable circumstance is, that red 

 bark contains more of cinchonine than the grey bark, inde- 

 pendent of the quantity of quinine ; and the latter is more 

 considerable than the quantity of quinine given by an equal 

 portion of the yellow bark. 



As to the real quantities of these alkalis contained in the 

 cinchonas, all estimations as yet given are merely approxi- 

 mations from the loss of matter, which occurs in the process 

 of separation ; and for the same reason it will not be proper to 

 deduce the activity of these alkalis, in a medical point of 

 view, from the quantity given by a certain weight of bark. 

 Neither do we recommend the substitution of these alkalis 

 for the substances from which they are obtained, until some 

 practitioner, joining prudence with wisdom, pursue these me- 

 dical investigations of the alkalis of cinchona, and thus give 

 to our works a really useful medical character. 



After cinchonine and quinine, the substance occurring in 

 bark, which appears to us most remarkable, is the red matter 

 already described by Reuss. A singular property of this sub- 

 stance, not observed by Reuss, is its convertibility into tannin 

 by the successive action of alkalis and acids. It acquires this 

 property by being dissolved in water, acted on by an alkali, and 

 afterwards separated from the alkali by an acid. It thus even 

 precipitates gelatine. 



[We have received from our Paris Correspondent several Scientific Com- 

 munications, which the pressure of other matter has obliged us to 

 omit. Among- these are the details of M. Ampere's Electro-magnetic 

 Researches, which, having been in part laid before the Royal Society, 

 and not leading to any important general conclusions, v.e have not 

 thought necessary to insert in this Number.] 



