BY DR. LAUDER BRUNTON. 497 



hol, and glycerin. Its solutions have a j^ellow or brownish-red 

 color, which is so intense that it is distinguishable in a layer 

 1.5 centimetres thick of a solution containing one part in 

 500,000. 



Bilirubin combines with alkalies, forming compounds which 

 are soluble in weak alkaline liquids, which are precipitated by 

 neutralization. They are insoluble in chloroform, the chloro- 

 form solution bilirubin being precipitated by alkalies. For 

 this reason it is necessary to acidify bile before extracting the 

 bilirubin with chloroform. Bilirubin also combines with Lime. 

 If bilirubin is dissolved in ammonia, and the solution pre- 

 cipitated with calcium chloride, a rusty-red flocculent precipi- 

 tate is obtained, which is a calcium compound of bilirubin. 



* 137. Biliverdin. C 16 H 20 N .,O, or C ]6 H 18 N,0 4 . Preparation. 

 Put an alkaline solution of bilirubin in a flat shallow vessel, 

 and let it stand exposed to the air for a considerable time, 

 until it becomes green. Precipitate it with hydrochloric acid, 

 wash the precipitate with water, dissolve it in alcohol, filter, 

 and evaporate. The biliverdin is left as an amorphous body. 

 The reaction by which bilirubin is converted into biliverdin is 

 considered by Staedeler to be C 16 H 18 N 2 O s -fH 2 0-|-0==C 16 H.. 

 N.0 6 . 



Properties. It is insoluble in water, ether, and chloroform. 

 It is soluble in 1, alcohol (and can thus be separated from 

 bilirubin, which is insoluble), 2, dilute liquor potassae, or 3, 

 ammonia, and 4, strong sulphuric acid. It is precipitated from 

 its alkaline solution by acids, or by salts of calcium, barium, 

 or lead. It is precipitated unchanged from its solution in sul- 

 phuric acid by the addition of water. Nitric acid oxidizes bili- 

 verdin in alkaline solutions, and produces the same series of 

 colors as with bilirubin. Sulphurous acid, which is a powerful 

 deoxidizing agent, causes alkaline solutions of biliverdin, espe- 

 cially when warmed, to become yellow ; when the yellow solu- 

 tion is treated with nitric acid, it behaves just like a solution 

 of bilirubin. 



138. Relation of Bile Pigments to Haemoglobin. Bili- 

 rubin is generally believed to be formed from haemoglobin, 

 which becomes altered during the passage of blood through 

 the liver. The grounds for this belief are the apparent identity 

 of bilirubin, and the pigment called haematoidin, found in old 

 extravasations of blood, and the observation that bile pigments 

 appear in the urine after the injection into the veins of solu- 

 tions of haemoglobin or of any substance which will dissolve 

 the blood corpuscles, and liberate haemoglobin, such as water 

 (Herrmann), bile acids (Frerichs Kiihne), or ether (Tiegel). 

 They also appear after prolonged inhalation of ether (Noth- 

 nagel), or chloroform (Bernstein). Further support is also 

 lent to this view by the destruction of haemoglobin, which 

 32 



