166 THE DIGESTIVE FLUIDS. 



/CH.OH 



the formula : C 20 H 31 (CH 2 .OH) 2 . Of its structure, however, and 



\COOH 



of its origin nothing is known. Some investigators have suggested 

 a chemical relation between it and cholesterin, but there are no 

 definite data to support this view. It combines with alkalies and 

 alkaline earths, as also with the heavy metals, to form salts. Its 

 compounds \vith the alkalies are readily soluble in Avater, but Avith 

 some difficulty in alcohol. The barium salt is somewhat soluble in 

 Avater, and, like the lead salt, soluble in hot alcohol. The calcium 

 salt is slightly soluble in boiling alcohol. Concentrated solutions of 

 the alkaline hydrates and carbonates precipitate the alkaline salts 

 from their solutions in the form of an oily material which becomes 

 crystalline on cooling. The salts, like the free acids, are dextro- 

 rotatory. 



On prolonged boiling with acids or at a temperature of 200 C. 

 cholalic acid loses two molecules of water and is transformed into 

 dyslysin, as shown in the equation : 



C 24 H 40 5 = C 24 H 36 3 -f 2H 2 

 Cholalic Dyslysin. 

 acid. 



The same result is brought about through the influence of various 

 bacteria, and there can be no doubt that the dyslysin which is con- 

 stantly encountered in the stools is referable to the normal processes 

 of putrefaction, Avhich take place in the intestinal canal. 



The common dyslysin which is met with in the feces is amorphous, 

 and is insoluble in water and in dilute solutions of the alkalies. 



Choloidinic acid, C^H^O^ probably represents an intermediary 

 product which is formed during this process, and may be regarded 

 as a primary anhydride of cholalic acid. 



On oxidation Avith permanganate cholalic acid first yields dehydro- 

 cholalic acid, and then bUianic acid, together with isobilianic acid. 

 These changes may be represented by the equations : 



(1) C 24 H 40 O 5 + 3O C 24 H 34 O 5 -f 3H 2 O 

 Cholalic Dehydrocholalic 



acid. acid. 



(2) C 24 H 34 5 + 30 : : C 24 H 34 8 

 Dehydrochol- Bilianic 



alic acid. acid. 



On further oxidation another acid has been obtained, Avhich is 

 termed cilianic acid, C 20 H 28 O 8 . 



Dehydrocholalic acid also results on oxidizing cholalic acid with 

 nitric acid ; but it is to be noted that on further oxidation a neAV 

 acid results, which is known as choleocamphoric acid, and is thought 

 to be isomeric Avith camphoric acid. Its formula is given as C 10 H 16 O 4 . 

 On oxidation Avith potassium bichromate and sulphuric acid, on the 

 other hand, Tappeiner claims to have obtained cliolesteric acid (not 

 to be confounded with cholesterinic acid, see below), C 12 H 16 O 7 ; 

 pyrocliolesteric acid, C n H 16 O 7 ; cholanic acid, C 20 H 28 O 6 ; as also 

 palmitic, stearic, and acetic acids. 



