ANALYSES OF THE CINCHONA BARKS ON EXHIBITION IN THE 

 MATERIA MEDIC A SECTION. U. S. NATIONAL MUSEUM. 



BIT OEORCE E. DOERINC}, PBAR. D. 



The collection ot cinchona barks now on exhibition in the materia 

 medica section of this museum represents about all the varieties that 

 are to be found in commerce. They were received mostly from the 

 Government plantations of India, Government plantations of Jamaica, 

 Messrs. Howard & Sons, London, Messrs. W. H. Schieffelin & Co., New 

 York, and the U. S. Centennial Exhibition, 1876. 



The collection comprises nearly all the natural barks of South Amer- 

 ica, and almost every variety of the cultiv^ated product from the planta- 

 tions in India, Java, Ceylon, Mexico, and Jamaica. They number in 

 all over a hundred specimens. 



With such a large and varied collection the question naturally arose, 

 what is the comparative value of these barks'? To answer this it was 

 simply necessary to assay them, which was accordingly undertaken at 

 the suggestion of the present curator. Dr. H. G. Beyer, U. S. N. 

 (Some specimens existed in such a limited quantity that even the small 

 amount of 5 grams could not be spared, and thus had to be omitted 

 from the list given below.) 



Through the courtesy of Prof. F. W. Clarke I was allowed to do the 

 work in the laboratory of the U. S. Geological Survey. 



Many of the methods' described in the books for determining the 

 amount of cinchona alkaloids were tried, with the view of obtaining 

 one which would give the smoothest results. The following is a de- 

 scription of the method employed : 



(I) Five grams of the finely powdered bark are first digested for 

 several hours with 100°*= of a 1 per cent, solution of sotlium hydrate, 

 filtered, and the contents of the filter washed with an additional 50«<' of 

 alkaline solution. (This preliminary operation is to remove tannin, 

 coloring, and other objectionable substances, which greatly interfere 

 with the subsequent removal of alkaloids by chloroform.) This solution 

 is then made acid, filtered from the precipitated cinchona red, the 

 filtrate rendered alkaline, and such alkaloids as may have been dis- 

 solved are removed with chloroform, the chloroformjc solution evapo- 

 rated, and the residue weighed. This weight is to be added to the 

 final result. 



(3) The bark so prepared is now transferred to a flask, with lOO"" of 

 a 2 J per cent, solution of sulphuric acid, and digested for several hours 

 on a water-bath ; filter and repeat the operation, washing the filter 

 until the filtrate ceases to become turbid upon the addition of sodium 

 hydrate. (The bark that has so far as possible been exhausted of 



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