152 THE DIGESTIVE FLUIDS. 



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

 water, 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 

 crvstalline on cooling. The salts, like the free acid, 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 6 = C 24 H M 3 + 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, which take place in the intestinal canal. 



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

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

 as a primary anhydride of cholalic acid. 



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

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



On oxidation with permanganate cholalic acid first yields dehydro- 

 cholalic add, and then bilianic aeid, together with isobilianic acid. 

 These changes may be represented by the equations : 



(1) C 24 H 40 5 + 30 = C M H SI 5 + 3H 2 

 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, which is 

 termed cilianic acid, and which is said to have the composition 



QjoJW 



Dehydrocholalic acid also results on oxidizing cholalic acid with 



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

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

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

 On oxidation with potassium bichromate and sulphuric acid, on the 

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

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

 pyrocholesteric acid, C U H 16 O 7 ; cholanic acid, C 20 H 28 O 6 ; as also 

 palmitic, stearic, and acetic acids. 



On reduction, as during the process of putrefaction, cholalic acid 

 may give rise to the formation of desoxycholalic acid, C 24 H 40 O 4 . On 

 boiling with concentrated solutions of the alkaline hydrates a mixt- 

 ure of the corresponding salts of formic acid, acetic acid, propionic 

 acid, and palmitic acid is obtained, and it is interesting to note that 

 the latter, like cholalic acid, gives Pettenkofer's reaction. 



