OXYTOLUIC ACIDS, ETC. 351 



dies, which are very slightly soluble in cold water. It 

 also unites with bases and acids. When a mixture of 

 ty rosin with nitric acid is evaporated at a slightly 

 elevated temperature, dinitrotyrosin, C 9 H 9 (E&quot;0 2 ) 2 X0 3 , is 

 formed. This crystallizes in golden-yellow laminse. 

 Simultaneously with these two compounds, a red color 

 ing matter (erythrosin) is produced by the action of 

 nitric acid on tyrosin. When heated with concen 

 trated sulphuric acid, tyrosin yields several sulpho- 

 acids, the soluble salts of which are colored a beautiful 

 violet by iipn chloride. 



2. Acids, C 8 H 8 3 . 



a. Oxytoluic Acids (Cresotic Acids). 



(OH 



C 6 H 3 1 CH 3 

 ( CO.OIL 



Three acids of this composition are known. They are 

 formed, like salicylic acid, by the simultaneous action 

 of sodium and carbonic anhydride on the three modifi 

 cations of cresol (p. 298). 



a-Cresotic acid, From para-cresol Long, colorless 

 needles; fusing point, 147-150. 



0-Cresotic acid. From ortho-cresol. Long, color 

 less needles ; fusing point, 114. 



r-Cresotic acid. From meta-cresol. Needles; 

 fusing point, 168-173.. 



The solutions of all three acids are colored violet by 

 iron chloride. 



b. Oxymethylphenylformic Acid. 



CH .OH 



CO.OH. 

 When para-toluic acid is treated with bromine with 



( f^T-T2~Pri 



the aid of heat, an acid C 6 H 4 j CQ OH is produced, 

 which as yet has not been prepared in a pure condition. 



