226 



the absorption spectruni of solutions obtained by treating tbe three 

 porphyrins witii broniinc in tbe nianner described bv Mr. Scluinck 

 and myself '). 



C J a ^ 



!.. iil]yllopor[il]yrm + Br 

 2., mesoporphyrin + Br 



H., haematoporphyrin 4- Br 



The stated properties of mesoporphyrin may be taken as 

 a proof of the contention, previously expres.sed, that by reinoving 

 hydroxyls gradually from tlie molécule of haematoporphyrin and 

 substituting hydro;^en \ve shall in the end obtain phylloporphyrin. 



The electrolytic dissociation o f haem atop or phy- 

 rin salts. By a method identical with the one used in the case 

 of phylloporphyrin salts-), it is possible to show that haematoporphyrin 

 salts dissociate ellectrolytically in aqueous solutions. Haematopor- 

 phyrin is a weaker base than phylloporphyrin and, in order to pre- 

 vent hydrolytic dissociation, it is necessary to apply solutions con- 

 taining a greater excess of free acids than in the former case. 

 The reproduction of photographs on plate II show that the absorp- 

 tion spectra are identical, no matter what acid bas been used to 

 neutralise the colouring- matter. 



') tlourn. cheiii. Suciety, London 190Ü, p. 1091. 



^1 Bull. Intern, de l'Académie des Sciences de Cracovie, Classe des Scien- 

 ces mathématiques et naturelles«, 1902, p. 5. 



