THE BILE. 



215 



both codeine and morphine, has a spectrum very similar to that of the 

 biliary salts. If the ruddy color of the fluid be strongly pronounced, 

 its spectrum, even when viewed in a layer of one centimetre, is very 

 short, terminating completely about midway between D and E, or even 

 before that point, showing the red and yellow clear and bright, but very 

 little of the green. If diluted with water, the mixture is not rendered 

 turbid, but its color is very much reduced, being soon changed to a 

 faint amber or often to a light apple-green, while the former peculiari- 

 ties of the spectrum disappear. The best way is to place the fluid 

 before the slit of the spectroscope in a layer of two centimetres before 

 its color is fully developed, and while it is still of a light pink. The 

 color then gradually becomes more pronounced, and, when it has at- 

 tained the proper degree of strength, the spectrum exhibits a certain 

 though ill-defined absorption-band at E. Beyond the band, the whole 

 spectrum is very dim, and terminates gradually between F and G. 



The distinction between the spectrum of Pettenkofer's test with 

 biliary salts and that with the opium alkaloids is, that in the former 

 case the absorption-band at E is very marked and distinct, and often 

 quite black, when viewed in a layer of two centimetres' thickness, while 

 in the latter it is always dim and very ill-defined. With the biliary 

 salts, also, the fluid may frequently be diluted with its own or even 

 twice its volume of water, and the absorption-band still remain plainly 

 visible; but with morphine or codeine a very moderate dilution rapidly 

 destroys the character of the spectrum and causes the absorption-bar. d 

 to disappear. 



Fig. 73. 



SPECTRUM OF PETTENKOFEB'S TEST, with albumen. 



The violet-colored fluid produced by Pettenkofer's test with albumen 

 has a well-marked and peculiar spectrum, easily distinguishable from 

 that belonging to the biliary salts. If tolerably dense, it requires to be 

 diluted with water for spectroscopic examination, and afterward cleared 

 up by the further addition of sulphuric acid. The spectrum then shows 

 a single absorption-band, extending from somewhere about the line E 

 to the line F, and occupying the intermediate space. In concentrated 

 specimens it may begin considerably to the left of E, and extend thence 

 to F. If the albuminous liquid be more dilute, it may reach only from 



