EPIPOLIC DISPERSION OF LIGHT. 145 



Received February 20, 1845. 



P.S. — Having been obligingly favoured by Professor Daniell with specimens of 

 very pure cinciionine and salicine, I am enabled to state that they do not possess in 

 the smallest appreciable degree the curious property above shown to belong to qui- 

 nine. 



As regards the latter alkaloid, all the acids I have tried appear to produce the 

 same effect, though not all in an equal degree. The muriatic seems least efficacious ; 

 the sulphuric and acetic decidedly the most so. The intensity of the superficial 

 colour produced when either of the latter acids (very dilute) is used, is really sur- 

 prising. 



Only acid solutions succeed. After precipitating by excess of potash a solution of 

 quinine, the liquid filtered was very bitter, and of course contained quinine. It 

 however exhibited no trace of superficial colour; but on dropping powdered tartaric 

 acid into the test glass the blue colour was instantly developed, and seen to follow 

 the course of the descending acid. 



J. F. W. H. 



Feb. 16, 1845. 



MDCCCXLV. U 



