MARCEL NENCKI, 1847— 1901 527 



and Madame Sieber were the first, in 1884, to prepare the 

 crystals on a large scale and to determine their composition 

 by chemical analysis. The subject was afterwards investigated 

 by other observers, amongst whom may be mentioned Cloetta, 

 Morner, Schalfejew, and Rosenfeld. Various methods were 

 employed and various formulae assigned to the crystalline 

 products obtained. The final credit, however, for bringing 

 order into the chaos created by so many contradictory results 

 must be assigned to Kiister, who showed that the pro- 

 ducts obtained by the different observers were identical, only 

 in different states of purity. He showed that the crystalline 

 11 haemines " were not all entirely soluble in chloroform con- 

 taining quinine or pyridine ; if such a solution, after filtering 

 off from the insoluble residue, be thrown into acetic acid 

 containing hydrochloric acid, a crystalline compound separates 

 out, to which the composition represented by the formula 

 CsiH-tfOJMiOFe must be assigned. Nencki and Zaleski prepared 

 various derivatives from haematin. The most important of 

 these was haematoporphyrin, which can be obtained by the 

 action of hydrobromic acid. This in its free state is a halogen- 

 free and iron-free body, and its preparation from bromine can 

 be represented by the following equation : 



C 34 H w 4 N 4 ClFe + 2HBr + 2H 3 = C 3t U 3S O s ^ l + FeBr, + HC1. 



An additional stimulus was given to the investigation of the 

 blood pigments by some researches which were being carried 

 out by Schunck and Marchlewski on chlorophyll. From this 

 plant pigment these observers obtained a series of derivatives, 

 the formation of which can be schematically represented as 

 follows : 



Chlorophyll 



[NaOH] [Weak acid] 



Alkachlorophyll Chlorophyllan 



1[HC1 4- Alcohol] ^ [Strong acid] 



Phylloxanthin 

 ^ [Strong acid] 

 Ethyl phyllotaonin Phyllocyanin 



v[KOH] • [KOH or HC1] 



Phyllotaonin. 



Now phyllotaonin was found by Schunck and Marchlewski 

 to yield, on treatment with alcoholic potash, a body having a 

 spectrum very similar to haematoporphyrin. To it was assigned 



