OXYSALICYLIC ACID, ETC. 355 



water of crystallization. Soluble in hot water in almost 

 every proportion. Fuses at 70-80 while still contain- 

 ing water; in an anhydrous condition at 104. 



Phenylbromlactic acid, C 9 H 9 Br0 3 . Is obtained 

 from cinnamic acid dibromide, by boiling with water. 

 Very similar to the chlorinated acid. Fuses in an 

 anhydrous condition at 125. 



4. Acids, C n H 14 3 . 



fOH 

 Thymotic acid, C 6 H 2 -| C3 j_p Is formed from 



tCO.OH. 



thymol (p. 300) by the simultaneous action of sodium 

 and carbonic anhydride. Long, fine needles ; very 

 difficultly soluble in water ; fuses at 120, and is sub- 

 limable without decomposition. The solutions of the 

 acid and those of its salts, particularly that of the 

 ammonium salt, turn a beautiful blue when warmed 

 with iron chloride. When the potassium salt is heated 

 with phosphorus chloride, or when the free acid is 

 heated with phosphoric anhydride, a substance called 

 thymotide, C n H 12 2 , is produced. This crystallizes well, 

 and fuses at 187. 



c. Monobasic, Triatomic Acids. 



1. Dioxybenzoic adds. 

 C'H'O'-C'H'jffiSj. 



Three isomeric acids of this composition are posi- 

 tively known. 



1. Oxysalicylic acid. Is produced when a solu- 

 tion of monoiodosalicylic acid is boiled with concen- 

 trated potassa-ley until on acidifying no precipitate 

 is formed. It may now be extracted from the acidified 

 solution by agitating with ether. Lustrous needles; 



