216 Dr. Thudichum on the Colouring -matters of Bile. [Dec. 12, 



N3 Og, Ba= 20* 75 per cent., and precipitated by neutral Ba salts from a 

 neutral solution in ammonia. The differences between these salts were 

 established in all their details by analyses, the means of which compare 

 with theory as follows : — 



Neutral salt. Half-acid salt. 



Atom. W. 477. Atom. W. 660. 



Theory. Found. Theory. Found. 



€ 43-46 44-58 49-09 50-63 



H 4-02 3-98 4-39 4-37 



Ba 27-56 27-55 20-75 20-66 



The discovery of these salts was of particular importance, as they led to 

 the discovery of similar calcium compounds, and thereby to important 

 theoretical developments. 



The neutral calcium-salt, The half-acid calcium-salt, 



€,J-l,,€aN,0,. €,,H,,.gaN3 0,. 



Atom. W. 400. Atom; W. 563. 



Theory. Found. Theory. Found. 



C 54 53-86 57-54 60-37 



H 5 4-90 5-15 5-74 



€a 10 10-17 7-10 6-91 



The calcium compound, on the basis of which Stadeler had assumed 

 g^gH^gN^Og to be the atomic formula of bilirubine, had yielded him (one 

 analysis) 9-1 percent, of calcium oxide, therefore less calcium than was found 

 in the analysis of the half-acid salt, or 6*5 per cent. There is no doubt that 

 Stadeler had this half-acid compound before him. He unfortunately ob- 

 tained the most unstable and uncertain of all the com.pounds of bilirubine, 

 and mistook it for a neutral salt, abandoning his former correct analysis 

 and formula of free bilirubine. With Stadeler' s last formula of bilirubine fall 

 the formulae of all other substances described by him under the names of 

 biliverdiiie, biliprasin, bilifuscine, and bilihumine. 



The half-acid cholophcEinate of sine, C^^ H^g Zn N3 Og, with 11-05 per 

 cent, of Zn, and the neutral cholophcainaie of lead, G^^ H^q ?b Og, 

 Pb = 36-50 per cent., were also obtained. Basic cholophceinate of lead is 

 analogous to the basic silver-salt, as in it two atoms of hydrogen are re- 

 placed by one didynamic atom of lead. Formula = GgH7iPb N02,-Pb = 56*25 

 per cent. 



Some copper compounds were also obtained. 



A new reaction for cholophseine is given. It consists in dissolving 

 the dry powder in fuming sulphuric acid. A splendid green is at once 

 produced. The substance is not biliverdine, but a product which, 

 when isolated, contains an atom of water more than bilirubine, and is 

 €9 NO,, and is named cholothalline by the author. Cholothalline 

 colours wool of a fast green, iudestructible b^ acid, discharged by ^mmoni^, 



PjiplophNwe also yields ft ^lue^poloured siibstanpe l)y fyefttmfwt ^it)i 



