CERTAIN ALKALOIDAL PERIODIDES. 



257 



pipetted into a suitable glass stoppered bottle, approximately 50 cubic 



centimeters of tq sulphuric acid added, the desired amount of iodine 



solution run in and the volume made up to approximately 200 cubic 

 centimeters with distilled water. The bottle was then thoroughly shaken 

 and set aside over night. The final determination was made by filtering 

 the solution through abestos, rapidly washing the bottle and precipitate 

 with a small amount of water and determining the residual free iodine 

 in the combined filtrates by titration with thiosulphate solution. 



The physical characteristics of the precipitates are of interest. As 

 a rule they come down as finely divided compounds of a light reddish- 

 brown color which quickly becomes darker in the presence of any con- 

 siderable excess of iodine. When the concentration of iodine in the 

 solution is low, the codeine precipitates are plainly crystalline, and a 

 tendency toward the formation of crystals in the morphine solutions is 

 also observed, although no well-defined individuals are found, while the 

 heroin precipitates are all apparently amorphous. With comparatively 

 high concentrations of iodine the precipitates of all three alkaloids arc 

 black and of a pitchy or even oily consistency. The data from these 

 experiments are given in the following table : 



Table I. — Formation of the periodides of morphine, codeine, and heroin in acid 



solution. 



MORPHINE. 



Num- 

 ber 

 of ex- 

 peri- 

 ment. 



Grams 

 alkaloid. 



Grams 

 alkaloid 

 per cubic 

 centime- 

 ter solu- 

 tion. 



Iodine solution. 



Excess 

 iodine -^ 



iodine 

 used up. 



Atoms of 

 iodine— 



Run in. 



Used up. 



Excess. 



Per mol- 

 ecule 

 alka- 



Com- 

 bined 

 with 1 

 mole- 

 cu le of 















loid. 



alkaloid 



















in perio- 



















dide. 









cc. 



ce. 



cc. 









1 



. 03971 



. 00016 



6.37 



1.49 



4.88 



3.27 



4.57 



1.07 



2 



. 03971 



. 00016 



31.71 



5.31 



26.40 



4.97 



22.77 



3.81 



3 



. 03971 



. 00016 



43.44 



6.95 



36.49 



5.23 



31.78 



4.99 



4 



. 03971 



. 00016 



63.11 



7.95 



55.16 



6.93 



45.32 



5.71 



5 



. 03971 



.00016 



126. 22 



10.90 



115. 32 



10.59 



92.65 



7.83 



CODEINE. 



6 



. 03894 



. 00017 



6.31 



4.12 



2.19 



0.53 



4.84 



3.17 



7 



. 03894 



.00017 



26.43 



8.14 



18.29 



2.24 



20.31 



6.25 



8 



. 03894 



. 00017 



44.63 



10.28 



34.35 



3.34 



34.29 



7.90 



9 



.03894 



.00017 



63.07 



11.72 



51. 35 



4.38 



48.45 



9.00 



10 



.03894 



. 00017 



126.22 



15.56 



110.66 



7.11 



96.97 



11. 95 



