318 BILIRUBIN. [BOOK n. 



By the action of barium chloride, lead acetate, and nitrate of 

 silver on ammoniacal solutions of bilirubin, compounds similar to 

 the calcium compound can be obtained. The silver compound occurs 

 in violet-coloured flakes and is not reduced even when the liquid in 

 which it is suspended is boiled. Bilirubin, as Maly observes, shews 

 by the compounds which it forms, that it has the character of a weak 

 acid. 



Composition Heintz 1 was the first chemist to make an ultimate 



and formula. analysis of bilirubin, and assigned to it the formula 

 C 16 H 18 N 2 5 . The method which he followed in the preparation of 

 the substance, which was not until later obtained crystallised, renders 

 it certain that it was not free from impurities, and the results of his 

 analysis may therefore be left out of consideration. The same objec- 

 tion does not apply to Stadeler's methods. The results of his work 

 have been absolutely confirmed by the more recent and exhaustive 

 researches of Maly, as well as by Hoppe-Seyler 2 . Both Stadeler 

 and Maly from their analyses deduced for bilirubin the formula 

 C 16 H 18 N 2 O 3 . Thudichum 3 , on the other hand, has assigned to bilirubin 

 the formula C 9 H 9 N0 2 , which neither agrees with the concordant 

 analytical results of Stadeler and Maly, nor fits in with many facts 

 with which we are acquainted. The reader will see at a glance how 

 considerable are the differences in the percentage of the various 

 elements calculated from Stadeler and Maly's formula on the one 

 hand, and from that of Thudichum on the other. 



(Stadeler and Maly.) (Thudichum.) 



C 16 H 18 N 2 3 C 9 H 9 N0 2 



or C 32 H 36 N 4 6 



Carbon 6713 66'25 



Hydrogen 6'29 5'52 



Nitrogen 979 8'59 



Oxygen 1679 19'64 



100-00 100-00 



Quite apart from the remarkable concordance of the results of 

 Stadeler and of Maly, an examination of all facts bearing on the 

 question 4 has led chemists to the opinion that the formula of 



1 Heintz, Poggendorff s Annalen, Vol. LXXXIV. p. 106. 



2 " Ausser diesen Ergebnissen der Untersuchungen von Stadeler sind noch von 

 Maly und von Thudichum solche verb'ffentlicht, von denen die Kesultate Maly's 

 Bestatigung der Untersuchungen Stadeler's gebeii. Die Analysen von Hoppe-Seyler 

 lassen gleichfalls keinen Zweifel an der Eichtigkeit der Formel von Stadeler und von 

 Maly." Hoppe-Seyler, Handbuch d. Phys. u. Path. Chem. Analys., 6th ed., (1893), 

 p. 226. 



3 Thudichum, Journ. f. prakt. Chem., Vol. civ. (1868), p. 193. 



4 Such as the results of the analysis of the calcium compound of bilirubin, of 

 Maly's tribromobilirubin, no less than the relation of bilirubin to biliverdin ; to the 

 latter point reference will again be made. 



