HYDKOSORBIC ACID. 125 



slightly soluble in cold water, more easily in hot 

 water and in alcohol; boiling point, 191. Sodium 

 amalgam produces no change in the acid in aqueous 

 solution, but when it is heated for a long time with 

 hydriodic acid and a little amorphous phosphorus at 

 180-200, it is completely converted into valeric acid. 

 Fusing caustic potassa resolves it into acetic and pro- 

 pionic acids. Combines directly with bromine, form- 

 ing the dibromide OTPBrW Crystals fusing at 76. 

 This dibromide is converted into angelic acid by the 

 action of sodium amalgam and water. 



Methylcrotonic acid, C 5 H 8 2 (isomeric with angelic 

 acid), is produced from isoxyvaleric acid in the same 

 manner as methacrylic acid. Colorless needles, fusing 

 at 62 ; conducts itself towards fusing potassa the same 

 as angelic acid. 



4. HydrosorUc Acid. 

 2 = C 5 H 9 .CO.OH. 



Is produced by the action of sodium amalgam and 

 water on sorbic acid. Colorless liquid, of a sweaty 

 odor, but slightly soluble in water ; specific gravity, 

 0.969 ; boiling point, 201. Does not congeal at 18 ; 

 melting potassa resolves it into butyric and carbonic 

 acids. 



The following acids are isomeric : 



Pyroterebic acid, C 6 H 10 2 . Is produced by the 

 destructive distillation of terebic acid (see Oil of Tur- 

 pentine). Oily liquid, boiling at 210. Is broken up 

 by means of fusing potassa, yielding acetic and butyric 

 acids. 



Ethylcrotonic acid, C 6 H 10 2 , is produced from 

 ethyl diethoxalate the same as methacrylic acid ; also 

 by heating ethyl diethoxalate for several hours with 

 concentrated hydrochloric acid at 130-150. Quad- 

 ratic prisms, fusing at 41.5. Conducts itself towards 

 potassa the same as pyroterebic acid. 



