M. Calvert on the Preparation of Quina and Cinchonia. 1 75 



The following experiment will demonstrate in a manner 

 perhaps still more evident, the non-formation of the sulphate 

 of lime, and will besides show how very sensible a test the 

 chloride of lime is to detect the presence of cinchonia. 



I took 2 grammes of the solution of sulphate of cinchonia, 

 containing 0*033, and diluted it with 48 grammes of water, 

 and had therefore 33 parts of this substance diffused in 

 50,000 parts of water ; to this solution I added a little chlo- 

 ride of lime, and obtained a precipitate of cinchonia, whereby 

 the sensibility of the chloride of lime, as a test of cinchonia, 

 as well as the non-precipitation of sulphate of lime, was de- 

 monstrated; for the sulphate of lime formed in the experi- 

 ment must have dissolved in the very dilute solution of cin- 

 chonia which was employed, and consequently the precipitate 

 which appeared could not be attributed to it. 



The experiment was tried with even double the quantity of 

 water, that is, with 33 parts of sulphate of cinchonia to 

 100,000 parts of water; but in this case the precipitate was 

 scarcely perceptible. 



2nd. The chloride of calcium does not precipitate a sul- 

 phate of quina, but it produces a precipitate with a sulphate of 

 cinchonia. 



3rd. The sulphate of quina gives a precipitate with lime- 

 water, but it disappears by an excess of the reagent being 

 added ; while, on the other hand, the sulphate of cinchonia 

 gives a precipitate which remains even on the addition of an 

 excess of the reagent. 



4th. The sulphate of quina gives a precipitate with am- 

 monia, which disappears on the addition of it in excess; 

 whereas, in the case of the sulphate of cinchonia, a precipi- 

 tate is produced which does not disappear on adding a large 

 excess of ammonia. 



5th. The carbonate of ammonia acts in precisely the same 

 way as ammonia. 



6th. With potash, a precipitate is produced with sulphate 

 of quina, but it re-dissolves almost entirely when the potash 

 is added in excess; while with a sulphate of cinchonia it 

 yields a curdy-white precipitate, which is insoluble in an ex- 

 cess of the reagent. 



7th. Soda precipitates the bases of both these salts, and the 

 precipitate does not re-dissolve on the addition of an excess ; 

 there is, however, this difference between the precipitate from 

 these two salts; that from the sulphate of quina is pulveru- 

 lent, while that from the sulphate of cinchonia is curdy- 

 white. 



By means of the first six tests, it will always be easy to di- 



