341 



ances of "fluorescence" upon the perpendicular wall of the glass 

 vessel exposed to the incident light ; whilst a bluish milkiness of 

 "internal dispersion" may he seen when I gr. of either alkaloid is 

 diluted with 700,000 grs. or 1C gallons of distilled water, well 

 acidulated in all these cases with sulphuric acid. 



Some other interesting results have followed from these investiga- 

 tions. When quinidin is dissolved in an excess of diluted sulphuric 

 acid, and the solution mixed with ahout twice its bulk of spiritj and 

 warmed to 130 F., and tincture of iodine then added in sufficient 

 quantity, and subsequently set in repose, beautiful red acicular cry- 

 stals are deposited ; these, upon recrystallization from rectified spirit, 

 acquire an increased size, become beautiful quadrilateral prisms, 

 leaving a deep garnet-red by transmitted light, and possessing a clear 

 bluish-purple reflected tint ; they are optically doubly absorbent in 

 a slight degree, and transmit a brownish-orange body-colour when 

 polarized perpendicular to axis. The primary form appears to be a 

 rhombic prism, and as far as my present analyses go, appears to 

 possess centesimallythe following composition : 



Iodine 39'665 



Sulphuric acid 6*273 



Carbon ... 32-890 



Hydrogen 3'960 



Nitrogen 4-400 



Oxygen 5-040 



Water . 8'504 



100-712 



The excess arises from the hydrogen twice calculated in water of 

 crystallization. 



These numbers agree very closely with the formula 

 (C3H'N 8 O + I) SO HO+5HO, 



and prove it to be the sulphate of iodo-quinidin, very analogous to 

 the optical quinine compound, yet differing materially in its optical 

 properties. 



There is another alkaloid frequently associated with quinidin, 

 which also crystallizes from spirit in the prismatic form like quinidin 

 and cinchonidin, but is another example of epipolism or fluorescence. 



2 D2 



