M. Calvert on the Preparation o/Quina and Cinchonia. 173 



I repeated this experiment several times both with the sul- 

 phuric and hydrochloric acids, and the result being always 

 similar, I concluded that all the quina had been precipitated 

 and none re-dissolved. 



To the other portion of the filtered and alkaline liquor, 

 after having saturated it with hydrochloric acid, I applied 

 chloride of lime, which is a very sensible test of the presence 

 ofcinchonia(aswill be made to appear presently), and having 

 obtained no precipitate, I felt satisfied from this experiment 

 that no particle either of quina or cinchonia had been re-dis- 

 solved : I therefore concluded, from the result of these ex- 

 periments, that the process of extracting those two vegeto- 

 alkalies by lime is imperfect, and I propose, instead of em- 

 ploying hydrate of lime for the purpose of precipitating the 

 alkaline bases of cinchonia, that caustic soda should be used, 

 because, by employing it, all the cinchonia, and especially 

 the quina, which may be contained in the acid liquors, will 

 certainly be precipitated ; — an object of great importance to 

 those who are engaged in this branch of manufacture. 



I afterwards endeavoured to discover a method by which 

 the quantity of cinchonia contained in sulphate of quina 

 might be easily ascertained, as the adulteration of the latter 

 by the addition of the former is a fraud frequently practised 

 in commerce, and one which is with difficulty detected by the 

 chemical means usually applied. For this purpose it has been 

 considered necessary to have recourse to a complicated ana- 

 lysis, especially should it be wished to ascertain the exact 

 extent of the adulteration. As in many works on chemistry 

 it is directed to treat the solution of those salts with an al- 

 kali, by which their bases are precipitated, to wash the pre- 

 cipitate, and then treat it with aether, which dissolves the 

 quina and not the cinchonia, I must here take the liberty of 

 remarking, that should such an analysis be undertaken, it will 

 be necessary to guard against using ammonia or potash, as a 

 small excess of these alkalies will re-dissolve a part of the qui- 

 na ; but, on the contrary, by employing soda this source of 

 error is avoided, no quina being re-dissolved. 



It is true that the end proposed can be compassed by fol- 

 lowing the directions indicated in many works on chemistry, 

 and using the precautions recommended in the concluding 

 part of the last paragraph. But it appeared to me that it 

 would be advantageous to employ tests by which the fraud in 

 question could be more easily discovered, and I succeeded by 

 the application of the six following reagents, and especially 

 the chloride of lime. 



I saturated two portions of cold water, one with very pure 



