18 THE SECRETIONS : 



it was required to ascertain the amount of bilin, bilifellinic acid, 

 and cholesterin, in a specimen of bile ; the fluid must be first 

 evaporated to dryness, and the amount of water thus estimated ; 

 the residue must be repeatedly extracted with ether, the ethe- 

 real solution evaporated to dryness, and its residue, consisting 

 of cholesterin and fluid fat, thoroughly washed with cold and 

 not too strong alcohol, which dissolves the greater portion of 

 the fluid fat. It must then be digested with hot alcohol of 

 0-83 ; and as this solution cools, the cholesterin separates in 

 crystals. After the removal of the fat, the residue is treated 

 with anhydrous alcohol, which takes up bilin, bilifellinic acid, 

 and biliverdin. The filtered alcoholic solution is then treated 

 with a solution of chloride of barium, as long as a dark green 

 precipitate falls ; and afterwards with baryta water, guttatim, as 

 long as it causes any turbidity ; it is then filtered, the excess 

 of baryta thrown down by a stream of carbonic acid, the car- 

 bonate of baryta removed by filtration, and the solution evapo- 

 rated to perfect dryness. The residue is dissolved in anhydrous 

 alcohol, all the bases are thrown down from the alcoholic solu- 

 tion by sulphuric acid dissolved in strong spirit, and then, after 

 filtration, the solution is mixed with moist, pure carbonate of 

 lead, and the greater part of the alcohol distilled. The fluid 

 remaining in the retort is removed by filtration from the inso- 

 luble portion, the lead removed by sulphuretted hydrogen, and 

 the fluid evaporated. The residue, after being extracted with 

 ether, leaves pure bilin mixed with a certain amount of fellinic 

 and cholinic acids, which must be separated with oxide of lead. 

 We then obtain pure bilin and bilifellinic acid combined with 

 oxide of lead. 



An accurate quantitative determination of the most important 

 ingredients of the bile, although difficult, is by no means im- 

 practicable. It is, however, very uncertain whether the result 

 of the analysis would afford any insight into the true character 

 of that changeable secretion. From the latest researches of 

 Berzelius, it appears that the bilin is so unstable a compound, 

 that it is hardly possible to obtain bile in the condition in which 

 it is secreted by the liver, or as it exists in the gall-bladder : 

 for when bile is left to itself, and much more when it is acted 

 on by heat and other more or less energetic agents, the bilin 

 undergoes a series of metamorphoses by which fellinic, cholinic, 



