ciatecl salts. possesing a common colonred ion. the liglit absorption 

 of aequimolecular solutions must be identical. The researches by 

 Ostwald hâve shown this conclusion to be correct. The scientist 

 named examined however fliieflv solutions of salts with coloured 

 negat.i\'e icms. 



Phylloporphyi'in is a eoniparativelv stmng base, tlie salts of 

 which produoe quite dift'erent absorption spectra than the free base 

 and niay be used therefore as an excellent example of salts 

 with coloured positive ions. The solutions of ])hylloporphyrin in neu- 

 tral solvents jiroduce. as far as tlie less refrangiltle part of the spec- 

 trum is c<incerned, 7 l)ands. whilst the solutions in minerai acids 

 cause, when examined in dilute solutions, only three bands. Assu- 

 ming that the formula CißHjgNjO expresses correctiy the compo- 

 sition of phylloporphyrin. tlie formula of the hydrochloric acid Com- 

 pound might be G]i;H,(^N.jü.HCl or CiiiHi,,N20Cl. similarly as in the 

 case of haematoporpliyrin. The same will hold good in the case of 

 salts derived from dtlier strong acids. Assuming further, that thèse 

 salts are dissociated electrolytically m aequous soluticms, \ve will 

 obtain in ail cases the coloured ion Cii;H,,,N.20 and the equimole- 

 cular soluti(ms of thèse salts ouglit to produce in the sjiectrum 

 identical absorjitions. Direct observations show that the assumption 

 madc is a correct one. The spectra of phylloporphyrin dissolved in 

 diluted solutions of hydrochloric. nitric an<l sulphuric acids show 

 three bands in the less refrangible part nt' the speetriim in abso- 

 lutely the saine position and a band just behind the k'. Une. disco- 

 vered by C. A. Schunck-"*) The reproductions of pbotographs, accompa- 

 nying this })apei', siiow this clcarlv altliuugh thcv «lo not do jus- 

 tice to the Originals. The solutions were prpi)ared as foUows: Equal 

 quantities of an alcoholic solution of ])hvlhjpor)ihvrin were added 

 to equal quantities of normal hydrochloric, nitric ami sulphuric 

 acids and the solutions obtained diluted by adding the same quan- 

 tities of water in each case tili suitable strengths for the spectro- 

 scopic examinations were produced. The solutions used for ]ihoto- 

 graphing the ultraviolet spectriim were diluted to such an extent, 

 that a colourati(jn of the liquid was scarcely perceptible. 



■') Proc. Koy. Soc. London <>3, .S89. 



