56 Analysis of the Protogcsa of Leibnitz. 



other substance insoluble in alcohol, the adulteration will easily" be 

 detected. 



2. It is soluble in acidulated water, say one drachm of sulphuric 

 acid to an ounce of water, which will readily dissolve the quinine. 

 By this means, if there is any stearine or margaric acid, (substances 

 prepared expressly for adulterating the article,) they will float on the 

 surface. 



3. It should give, by sal ammoniac, a white precipitate, rather 

 flaky, which is soluble in alcohol, and which, on being exposed to a 

 gentle heat, will consume without leaving the least residuum. 



4. After having dissolved it in acidulated water, it can be decom- 

 posed by means of a litde sal ammoniac; it must then be filtered' 

 and evaporated. If sugar has been introduced into it, it will be easi- 

 ly detected by the taste or by fire, which will produce its peculiar 

 odor. 



5. If a white substance, insoluble in cold water, be found in the 

 sulphate of quinine, heat the mixture to about 170° Fahr. This 

 will render the starch soluble, and its presence may be determined 

 by the addition of an aqueous solution of iodine, which will immedi- 

 ately occasion a blue color, and eventually a blue precipitate. The 

 iodine must be added in very small quantities and very slowly, or the 

 experiment will fail.* 



Art. VI. — Analysis of the Protogcea of Leibnitz; by Prof. E. 

 Mitchell,, of the University of North Carolina. 



As any science advances towards perfection, its early history, 

 though not always a matter of great importance, becomes never- 

 theless an object of interest. In stating the doctrines held by con- 

 temporary philosophers, we cannot well avoid some reference to the 

 opinions of those who have preceded us in the same field of investi- 

 gation and discovery, and if they are mentioned at all, it may well 

 be claimed that the account given of them should be fair and accu- 

 rate. I have supposed that a very brief analysis of the Protogaea 

 of Leibnitz might be acceptable to the readers of the Journal, and 



* Specimens of all the species of Peruvian bark, which now occur in commerce, 

 neatly put up in bottles, with a full description of each and a treatise on Cinchona, 

 can be had, for five dollars, at Geo. W. Carpenter's Chemical Warehouse, Phila- 

 delphia. 



