258 



HOLMES. 



Table I. — Formation of the periodides of morphine, etc. — Continued. 



HEROIN. 



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- 

 loid. 



Com- 

 bined 

 with 1 

 mole- 

 cule of 

 alkaloid 

 in perio- 

 dide. 









cc. 



cc. 



cc. 









11 



.05088 



.00017 



4.04 



0.83 



3.21 



3.99 



2.93 



0.60 



12 



. 05088 



. 00017 



6.90 



2.17 



4.73 



2.18 



5.01 



1.57 



13 



. 05088 



.00017 



6.92 



2.20 



4.72 



2.14 



5.02 



1.59 



14 



. 05088 



. 00017 



12.71 



4.85 



7.86 



1.62 



9.22 



3.52 



15 



. 05088 



.00017 



25.24 



7.96 



17.28 



2.16 



18.30 



5.78 



16 



.05088 



.00017 



32.99 



8.88 



24.11 



2.71 



23.94 



6.44 



17 



.05088 



.00017 



44.47 



9.79 



34.68 



3.54 



32.26 



7.10 



18 



. 05088 



.00017 



62.69 



10.10 



52. 59 



5.21 



45.49 



7.33 



19 



.05088 



.00017 



126.22 



10.58 



115.64 



10.93 



93.76 



7.67 



The free acidity of the solutions was approximately 0.2.5 gram sulphuric acid 

 in each experiment. 



The ratio of the equivalents of additive iodine to one molecule of 

 alkaloid in the compound or compounds resulting from the reaction was 

 calculated in each experiment from the weight of free iodine removed 

 from the solution and the weight of alkaloid originally present. No 

 tests were made to ascertain the degree of completeness of the precipita- 

 tion of the alkaloid. The solubility of periodides is known to depend 

 in a measure on the relative amounts of additive iodine in the compound, 

 the hydriodides being soluble and the solubility of the periodides de- 

 creasing as the amount of additive iodine is increased so that it was 

 considered probable, at least in those experiments where the concentra- 

 tion of iodine was low, that the precipitation of the alkaloid was incom- 

 plete and the appearance of the precipitates alone seemed to justify this 

 conclusion. The question of the influence of this effect on the results 

 obtained and the question of the accuracy of the results in general will 

 be considered later. 



A graphic presentation of the data is given in the curves of figures 

 1 and 2. It will be seen that the amounts of free iodine which com- 

 bine with the alkaloids are dependent in a perfectly reg-ular degree upon 

 the concentrations of free iodine in the solutions. The reactions of 

 morphine and codeine differ only in degree, but heroin, on the other 

 hand, presents some marked peculiarities. With heroin solutions and 



