118 RESINOUS ACIDS. 



alcohol ; the solution is decolorised by animal charcoal, and gra- 

 dually evaporated. 



Tests. This acid may be recognised with tolerable certainty by 

 the properties which we have already enumerated. If, however, it 

 be found in other places than in intestinal concretions, it should 

 always be submitted to an elementary analysis. 



Physiological Relations. 



Occurrence. According to the researches of Merklein and 

 Wohler,* as well as those of Taylor,t this body exists only in 

 certain bezoars, which are obtained from the intestines, and espe- 

 cially from the stomach of many species of goats inhabiting the 

 East ; other bezoars contain ellagic acid. 



Origin. Whether lithofellic acid takes its origin in the bile, 

 or is dependent on the use of resinous food, is as yet undecided, 

 since its similarity to the resins is as great as to the resinous acids 

 of the bile. Its analogy with ellagic acid certainly speaks in favour 

 of its origin from the food ; if, however, Taylor's view, that con- 

 cretions containing lithofellic acid are frequently found in the 

 stomach, be confirmed, it is obvious that they cannot owe their 

 origin to the bile. 



CHOLIC AciD.C 48 H 39 O 9 .HO. 



Chemical Relations. 



Properties. This acid crystallises in tetrahedra, and more 

 rarely in square octohedra, is colourless, glistening, and easily 

 pulverised ; the crystals effloresce on exposure to the air ; the acid 

 is bitter, leaving a faint sweetish after-taste ; it is soluble in 750 

 parts of boiling, and in 4000 parts of cold water ; it dissolves very 

 readily in alcohol, especially when heated, and in 27 parts of ether. 

 The acid, in crystallising from ether, forms rhombic tablets, and in 

 this form it contains 2 atoms of water, while from alcohol it crys- 

 tallises in tetrahedra with 5 atoms of water ; the acid separated 

 from alcohol by the addition of water contains 2 atoms of water, 

 which it loses at 100, while the tablets only lose 1 atom at that 

 temperature. Moreover, this acid strongly reddens litmus, fuses at 

 195, and at a higher temperature undergoes decomposition; above 

 195 it loses its atom of basic water, and is converted into choloidic 



* Ann. d. Ch. u. Pharm. Bd. 55, S. 120-143. 



t Lond., Edinb., and Dubl. Phil. Mag. vol. 28, pp. 192-200. 



