324 PROCEEDINGS OF THE AMERICAN ACADEMY 



admixture of a product containing a higher percentage of chlorine ; 

 the fraction A approached in composition the ethyl chlorpyromucate ; 

 while the fraction B was a mixture. In order to be quite sure of the 

 correctness of our conclusions, we treated these successive fractions 

 with an alcoholic solution of sodic hydrate, and obtained acids in each 

 case confirming the results of our analyses. From fraction A we 

 obtained an acid crystallizing from hot water in irregular leafy plates 

 which melted at 176-177°. The physical properties and melting 

 point were sufficient to identify this acid as the 8 chlorpyromucic acid 

 later described, and to prove that the lower boiling fraction consisted 

 chiefly of ethyl 8 chlorpyromucate. Fraction C yielded us without 

 difficulty, and in nearly theoretical quantity, an acid which when re- 

 crystallized twice from benzol melted sharply at 168-169°, and in other 

 respects proved to be identical with the ySy dichlorpyromucic acid 

 which we shall hereafter fully describe. The formation of this acid in 

 nearly theoretical quantity and without recognizable admixture proves 

 that the fraction C consisted of pure ethyl pyromucic tetrachloride. 

 Fraction D yielded us a somewhat less pure j3y dichlorpyromucic 

 acid, as did also fraction B. In the latter case, however, we were 

 able to isolate a small quantity of a sparingly soluble acid, crystal- 

 lizing from water in minute needles which closely resembled trichlor- 

 pyromucic acid. It was therefore evident that the main product formed 

 by the action of chlorine at 0° upon ethyl pyromucate was the tetra- 

 chloride and this might be distilled under diminished pressure without 

 essential decomposition. At the same time, it was shown that substi- 

 tution was effected even in the cold, and that the product contained 

 ethyl S chlorpyromucate and very possibly its tetrachloride. 



8 Chlorpyromucic Acid. 



Since substitution had taken place at low temperatures, it seemed 

 not unlikely that at 100^ the substitution might be so rapid as to offer 

 a convenient mode for the preparation of chlorpyromucic acids. Ethyl 

 pyromucate when treated with bromine at 100° yields 8 brompyro- 

 mucic and j38 brompyromucic acids still more readily than pyromucic 

 acid itself. We accordingly passed dry chlorine through ethyl pyromu- 

 cate heated to 100°, but found that a higher temperature was necessary 

 in order that substitution might promptly be effected. At 145° the 

 action was sufficiently rapid, and the chlorine was passed through the 

 melted ether at this temperature until a gain in weight was noted 

 which corresponded to the substitution of one hydrogen atom by chlo- 

 rine. The viscous liquid which was thus obtained was then slowly 



