H. EM A TOPORPH YRIN. 2 5 9 
(Hoppe-Seyler) ; (2) by the action of acetic acid saturated with HBr, 
aided by heat (Nencki and Sieber). 
Hsemochromogen is, in the absence of oxygen, converted even by the 
weakest acids into hsematoporphyrin, the iron being found in the 
solution as the ferrous salt of the acid employed. Although occurring 
more slowly, the decomposition of CO-haemochromogen by acids also 
yields hsematoporphyrin. 
According to Hoppe-Seyler, the composition of hsematoporphyrin is 
represented by the formula C 34 H 3 jiN^O,.. 
According to Xencki and Sieber, who have made the most complete 
investigation of this body, it has the composition C 16 H 18 N 2 3 , and they 
explain its origin from hsematin by the following equation, in which 
they adopt their own as distinguished from Hoppe-Seyler's formula for 
hsematin — 
C 32 H 30 N 4 FeO 3 +3H 2 O = 2(C 16 H 18 N 2 3 +Fe) 
(hrematin) 
According to Nencki and Sieber, hsematoporphyrin is isomeric with 
bilirubin. 
G h HK L M N 
Fig. 39. — The photographic spectrum of hsematoporphyrin. 
Physical and chemical properties. — Hsematoporphyrin forms beauti- 
ful crystalline compounds with Na and with HC1. 
It is insoluble in pure distilled water, slightly soluble in dilute acids, 
more soluble in strong acids, and readily soluble in alkaline solutions, 
weak and strong. It is also readily soluble in acid and alkaline alcohol. 
Solutions of hsematoporphyrin in acidulated alcohol have a beautiful 
purple colour, and assume a bluish violet tint when the solution is made 
very strongly acid. Alkaline solutions are of a fine red, but in the 
presence of a great excess of alkali exhibit a violet tint. Solutions of 
hsematoporphyrin, even if extraordinarily dilute, exhibit a magnificent 
red fluorescence, which strangely enough is not referred to in text-books, 
though it seems to me to be their most remarkable characteristic. 
An alcoholic solution of hsematoporphyrin, acidulated with hydro- 
