224 



drogen atoin wuuld cause the formatiim uf a substance witb absorp- 

 tion bands moved towards the violet end of the spectrum, i. e. the 

 spectrum of mesoporpbvrin will resemble even more that of phyllo- 

 porphyrin than does its uiothersubstance. haomatoporphyrin. The com- 

 parison of the spectra of mesoporphyrin and pbylloporphyrin bas 

 indeed shown that the différence between the two is infinitesimal, 

 scarcely measurable by methods hitberto applied in such cases. 



This resuit differs from the resuit of Nencki and Zaleslii '), inas- 

 much as thèse authors did not notice any différence in the ab- 

 sorption spectra of haematoporpbyrin and mesoporphyrin. The pre- 

 paring of solutions of mesoporphyrin is somewhat tedious, as this 

 substance when applied in the crystalline state dissolves in various 

 solvents only with great difficulty. I found this diffîeulty can be 

 overcome in the following manner. Mesoporphyrin is dissolved in 

 alcoholic potash, the solution diluted with water, acidulated with 

 acetic acid and quickly extracted with ether. 



In this manner strongly coloured solutions are obtained which 

 may be afterwards diluted as required. 



The measurement of wavelengths obtained for the absorption 

 bands of equally strongly coloured solutions of phyllojiorphyrin and 

 mesoporphyrin are as follows: 



The absorption of the violet and ultraviolet rays caused by 

 thèse two substances are also identical. Phylloporphyrin bas been 

 studied in this respect before by my friend Mr. C. A. Schunck. 



I hâve found in the spectrum of mesoporphyrin two bands, 

 the position of one of them corresponds exactly to the position of 

 the double band observed by Mr. Schunck in highly diluted phyllo- 



') Bull, international de rAoadémie des Sciences de Cracovio. Classe des 

 Sciences mathéin. et natur., 19U1, p. 217. 



