342 PROCEEDINGS OP THE AMERICAN ACADEMY 



temperatures ranging from 145° to its boiling point, both by itself and 

 after the addition of iodine or aluminic chloride, but in no case was 

 the desired product obtained. Pyromucic acid and 8 chlorpyroniucic 

 acid also failed to give such a product when treated at high tempera- 

 tures with chlorine, and we were equally unsuccessful when we used 

 the chloranhydrides of these acids either with or without an excess of 

 phosphoric pentachloride. We then studied the action of heat upon 

 the tetrachloride of pyromucic acid itself, of its chloranhydride and 

 ethyl ether, and of the ethyl ether of S chlorpyromucic acid, and found 

 in each case that small quantities of a dichlorpyromucic acid were 

 formed which closely resembled the (38 dibrompyromucic. A more 

 careful investigation further proved that in the decomposition of the 

 ethyl pyromucic tetrachloride a second new dichlorpyromucic acid was 

 formed concerning whose constitution we are not yet able to speak 

 definitely. This acid we propose to call the ^ dichlorpyromucic acid 

 until its structure is established. The amount of the dichlorpyromucic 

 acids which we have been able to obtain is but small, and we have 

 made many unsuccessful attempts to increase the yield by varying the 

 temperature or the mode of heating, or by adding iodine, or aluminic 

 or ferric chloride, before heating. 



We first obtained the (38 dichlorpyromucic acid by distilling under 

 ordinary pressure the product formed by treating pyromucic acid with 

 chlorine at 100°. Hydrochloric acid is given off in quantity, and, 

 although a large carbonaceous residue is left in the retort, a liquid 

 distillate is obtained which, after repeated distillation through a 

 Hempel's column, amounts to about 85 per cent of the weight of 

 the pyromucic acid taken and then distils leaving but an insignificant 

 carbonaceous residue. This distillate is extremely complex in its 

 nature and we have as yet made no thorough study of its constituents. 

 We found, however, that the portions which boiled between 196° and 

 220° gave considerable quantities of (38 dichlorpyromucic acid when 

 treated with cold water. They therefore contained the corresponding 

 chloranhydride of the acid. The yield thus obtained amounted to 

 but about 4 per cent of the pyromucic acid taken. From ethyl 

 pyromucic tetrachloride we succeeded in obtaining a somewhat better 

 yield. We found it advantageous to purify the tetrachloride by one 

 distillation in vacuo, and to distil the product thus obtained under 

 ordinary pressure. More or less carbonization ensued, and on frac- 

 tional distillation in vacuo through a Hempel's column * the distillate 



* For fractional distillation under diminished pressure we used the extremely 

 convenient apparatus of Anschiitz. We found that the ease of separation could 



