ADVANCED PHYSIOLOGICAL CHEMISTRY 455 



liver cells, but is only added to the bile as it passes along the bile ducts. 

 So far as can at present be ascertained, the amount of pigment and of 

 bile salts do not bear a quantitative relationship to one another, so that 

 it is improbable that they are both derived from the same source. 

 Quantitative estimations of these two bodies in bile, obtained from a 

 biliary fistule are, however, far from numerous, not only on account of 

 the rarity of suitable cases, but because there is no accurate method for 

 quantitatively determining the pigment. 



Separation of Bile Salts. To Separate all the Bile Salts. 

 Thoroughly mix 50 gr. pure animal charcoal with 200 c.c. of ox-bile in 

 an evaporating dish, and evaporate the mixture to dryness on a water 

 bath. During the drying the mixture should be frequently stirred. 

 The black powder thus obtained can be kept a considerable time. To 

 extract the bile salts from it, mix it with absolute alcohol in a flask and 

 place on the boiling water bath for about a quarter of an hour, cool, 

 filter into a dry beaker, and add ether to the filtrate till a permanent 

 haze is produced. Now cover the beaker with a ground-glass plate and 

 allow it to stand in a cool place till next day, when it will be found that 

 a crystalline mass of bile salts has separated out (Plattner's crystalline 

 bile). The crystals can now be collected on a filter paper and allowed 

 to dry in the air. 



A 1 per cent, solution of the crystals should now be made, and 

 Pettenkofer's reaction (see p. 233) applied to it by the following 

 method : 



Dissolve a few grains of cane sugar in the solution, and run con- 

 centrated sulphuric acid down the side of the tube so as to form a 

 layer underneath the watery solution. A violet ring is formed where 

 the two fluids meet. Now place the test-tube in a beaker of cold water, 

 and shake gently so as to mix the two fluids. A violet solution is thus 

 obtained. By cooling the test>tube in water too great a rise of 

 temperature is avoided. Divide the violet solution into two parts, A 

 and B. Add A to some ether and examine by means of the spectro- 

 scope a distinct band is seen in the green. Add B to some absolute 

 alcohol and note that, although the spectrum is at first the same as in 

 A, a band gradually develops in the blue, and that, along with the 

 development of this, the tint of the solution changes from green to 

 brown. 



To Prepare Pure Glycocholic Acid. In certain districts of Germany 

 and America it has been observed that the glycocholic acid can be 

 separated from the bile by a very simple process, and, so far as it has as 

 yet been tried, the bile obtained from oxen reared in this country 

 appears to be suitable for the process. 



