THE BILE. 



183 



51. 



lislied. But it is more particularly in their reaction with the salts 

 of lead that the difference between these substances becomes mani- 

 fest. For while the crystallizable substance of ox-bile is precipi- 

 tated by acetate of lead, that of dog's bile is not affected by it. If 

 dog's bile be evaporated to dryness, extracted with absolute alcohol, 

 the alcoholic solution precipitated by ether, and the ether precipitate 

 then dissolved in water, the addition of acetate of lead to the watery 

 solution produces not the slighest turbidity. If subacetate of lead 

 be then added in excess, a copious precipitate falls, composed of both 

 the crystallizable and uncrystallizable substances. If the lead pre- 

 cipitate be then separated by nitration, washed, and decomposed, 

 as above described, by carbonate of soda, the watery solution will 

 contain the re-formed soda salts of the bile. The watery solution 

 in a v then be evaporated to dryness, extracted with absolute alcohol, 

 and the alcoholic solution precipitated by ether ; when the ether 

 precipitate crystallizes partially after a time as in fresh bile. Both 

 the biliary matters of dog's bile are therefore 

 precipitable by subacetate of lead, but neither of 

 them by the acetate. Instead of calling them, 

 consequently, glyko-cholate and tauro cholate of 

 soda, we shall speak of them simply as the " crys- 

 talline' 1 and " resinous" biliary substances. 



In cat's bile, the biliary substances act very 

 much as in dog's bile. The ether precipitate of 

 the alcoholic solution contains here also a crys- 

 talline and a resinous substance ; both of which 

 are precipitable from their watery solution by 

 subacetate of lead, but neither of them by the 

 acetate. 



In pig's bile, on the other hand, there is no 

 crystallizable substance, but the ether precipitate 

 is altogether resinous in appearance. Notwith- 

 standing this, its watery solution precipitates 

 abundantly by both the acetate and subacetate of 

 lead. 



In human bile, again, there is no crystallizable 

 -substance. We have found that the dried bile, 

 extracted with absolute alcohol, makes a clear, brandy-red solution, 

 which precipitates abundantly with ether in excess ; but the ether 

 precipitate, if allowed to stand, shows no sign of crystallization, even 

 at the end of three weeks. (Fig. 51.) If the resinous precipitate 



HUMAN BILB, ex- 

 tracted -with absolute 

 alcohol and precipitated 

 by ether. 



