314 EARLY RESEARCHES ON THE BILE COLOURING MATTERS. [BOOK II. 



(Matiere jaune de la bile) as characteristic of the bile 1 , and L. Gmelin 

 in the researches of which he published the results with Tiedernann 2 , 

 studied with some care the properties which this colouring matter 

 presented in the bile of the dog. He shewed that when hydrochloric 

 acid is added to bile confined over mercury its colour undergoes no 

 perceptible change, whilst if oxygen be admitted the bile gradually 

 assumes a green colour. He pointed out that when nitric acid is 

 added to bile, changes in colour occur instantaneously and, under the 

 oxidising influence of this acid, without the intervention of atmo- 

 spheric oxygen. He discovered that nitric acid occasioned a rapid 

 succession of tints first green, then blue, violet, and last of all a 

 yellow or yellowish brown that the very tints of the rainbow pre- 

 sent themselves to the observer. "Man versetze Galle mit so viel 

 Salpetersaure, dass die blaue Farbung eintritt, libersattige mit Kali 

 und giesse dann Vitriolol in hinreichender Menge hinzu, so hat 

 man," he quaintly adds "em Stuck vom Regenbogen." From the 

 date of this description the succession of tints which the bile 

 colouring matters exhibit when treated with nitric acid has received 

 the name of 'Gmelin's reaction.' 



It was Berzelius 3 who first attempted the scientific study of the 

 colouring matters of the bile. To the brownish-yellow colouring 

 matter characteristic of the bile of man and the carnivora, he applied 

 the term cholepyrrhin 4 , though he confessed himself unable to 

 separate it in a state of purity from the bile itself, studying its 

 properties as observed in solutions, or as he extracted it from the 

 deposits which occurred in the gall bladder or from gall stones. 



He described cholepyrrhin as a nitrogenous body of a beautiful 

 reddish-yellow colour, tasteless and without odour, very sparingly 

 soluble in water and alcohol, and most readily dissolved in dilute 

 solutions of caustic potash or soda. He observed that these alkaline 

 solutions of the bile colouring matter absorbed atmospheric oxygen, 

 that the liquid gradually became green, and that when acids were 

 then added to it the colouring matter was precipitated in green 

 flakes. He described this colouring matter as in all respects similar 

 to chlorophyll, the colouring matter of leaves, with which he believed 

 it to be identical. As occurring in the bile he termed it, however, 

 biliverdin 5 , and he believed that the green colouring matter found in 

 the normal bile of the herbivora was produced from bilirubin by 

 processes occurring within the body which were identical with those 

 which he had studied in vitro. 



1 Thenard, ' Memoire sur la Bile,' lu a 1'Institut le 2 floreal, an 13, in Memoires de 

 Physique et de Chimie de la Societe d'Arcueil. Tome i. Paris, 1807, see pp. 2345. 



2 Tiedemann and Gmelin, Die Verdauung nach Versuchen, 1826, p. 79. 



3 Berzelius, see the account which he gives of his researches in his article ' Galle ' 

 in Wagner's Handworterbuch der Physiologic, Vol i. p. 522. 



4 From x 6X7 ?> bile and vvppbs, tawny, reddish-yellow (darker than cu/06s). The 

 name given by Berzelius appears both on etymological and descriptive grounds 

 preferable to the one which has supplanted it, viz. Bilirubin. 



5 'Ich habe es in diesem Zustand Biliverdin genannt.' Berzelius, loc. cit. p. 522. 



