225 
tained by Zaleski!). This author arrived at the conclusion that 
the process of dissolution of acethaemin into haematoporphyrin may 
be formulated by the following equation: 
C,H,0,N, FeCl4 2HBr2H,0—=C,H,0,N, Fe Br, HCl 
and as the haematoporphyrin obtained resembled in every respect, 
except in regards the composition, haematoporphyrin obtained for- 
merly by Nencki and Sieber from haemin, in the preparation of 
which no acetie acid was used, he concluded that acetie acid did 
not play any synthetical rôle in the formation of acethaemin. This 
research of Zaleski despite its great merits and the great experimental 
skill of its author, cannot however in our opinion settle the ques- 
tion of the haemin formula, as the proof is based upon the ana- 
lysis of haematoporphyrin and mesoporphyrin — a proof of a rather 
complicated character. Therefore, in spite of the researches of the 
three former authors and also those of Küster), not to mention 
many more earlier researches, the determination of the formula 
of haemin remained an unsolved problem. We think however that 
the present research of ours gives a final solution of the problem. We 
find that the first coloured derivative of haemoglobin formed under 
the action of acid on oxyhaemoglobin possesses indeed the formula 
C;,H,;0,N,FeCl, that is that acetie acid used in the preparation 
of so called acethaemin does not enter into the molecule as a con- 
stituent, but plays the rôle of a solvent only. Our proof is this: 
should acetic acid play the rôle of a synthetie agent in the pre- 
paration of ,acethaemin“, then any other organie acid with pro- 
perties resembling those of acetie acid should also behaye towards 
oxyhaemoglobin similarly, viz. it ought to produce, generally spea- 
king, an acylhaemin different from acethaemin. Propionic acid for 
instance should be expected to give a propionohaemin. As a matter 
of fact the substances obtained by either acetic acid or propionie 
acid are absolutely identical. 
We proceeded as follows: 1 litre of propionie acid, saturated 
with sodium chloride was heated to 95° and 200 em? of blood 
added. The mixture was heated up agin to 959 and after filtering 
left to erystallize. After two days standing the mother liquor was 
1) This Bulletin 1902 p. 512. 
2) Z. f. physiol. Chemie 1903. 
