GLYOCHOLIC ACID. 225 



cease to be acted on by the atmosphere. These crystals are a mix- 

 ture of the glycocholates of potash and soda. On precipitating the 

 aqueous solution of these crystals with acetate of lead, decomposing 

 the precipitate with carbonate of soda, evaporating the solution of 

 glycocholate of soda, re-dissolving in alcohol, and again (in the 

 same manner as before) crystallising by means of ether, we obtain 

 a tolerably pure glycocholate of soda, which, when dissolved in 

 water and treated with dilute sulphuric acid, after a time deposits 

 crystals mingled with oily globules. The latter may be removed 

 by washing with water, leaving the glycocholic acid in a state of 

 purity. 



The following is a shorter method of obtaining this acid. The 

 yellowish precipitate thrown down by sugar of lead from fresh bile 

 must be extracted with boiling spirit of 85^ and sulphuretted 

 hydrogen passed through the solution. If water be added to the 

 filtered fluid and the mixture be allowed to stand for a considerable 

 time, the acid will separate in a crystalline form ; in this case, 

 however, it is better to decompose the lead-salt by carbonate 

 of soda, and then to proceed in accordance with the former 

 method. 



Crystallised bile, which is a mixture of the glycocholates of 

 potash and soda, was first prepared by Platner.* 



Tests. In attempting to determine the amount of bile in an 

 animal fluid, it is always necessary that the albuminous matters, 

 the substances soluble in water only, and the fats, should be as 

 completely as possible separated. We consequently, in the first 

 place, obtain an alcoholic extract of the substance to be investi- 

 gated, and ascertain by Pettenkofer's test whether any derivative of 

 the bile be present in it. This point being decided, we can only 

 determine whether one of the acids contained in fresh bile glyco- 

 cholic or taurocholic acid, or one of their derivatives, cholic or 

 choloidic acid be present, when we have a considerable amount 

 of matter to work upon. To pursue this inquiry, we must 

 gradually add from 8 to 12 times its volume of ether to the extract 

 obtained by strong alcohol, and allow the mixture to stand for from 

 24 to 48 hours; by this time the turbidity of the fluid will have 

 disappeared, and a sediment will have formed, which is either 

 flocculent and viscid, so as to adhere to the walls of the vessel, (in 

 which case it consists for the most part of albuminous or extrac- 

 tive matter,) or is a resinous, semi-fluid, tough mass (alkaline 

 taurocholates or choloidates), or consists of tufts of well-formed 

 * Ann. d. Ch. u. Pharm. Bd. 51, S. 105 ; Journ. f. pr. Ch. Bd.40, S. 129-133. 



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