OF ARTS AND SCIENCES. 353 



Decomposition by Hydrochloric Acid. 



If the x dichlorpyromucic acid is heated with water in a sealed tube 

 to 170°, no change is effected, but a reaction which we had in no way 

 anticipated takes place if it is heated upon the water bath in an open 

 flask with concentrated hydrochloric acid. Carbonic acid is evolved, 

 and in a short time the acid is completely decomposed with the forma- 

 tion of a neutral body which volatilizes when the solution is boiled, 

 and which can be extracted, although with difficulty, from the distil- 

 late, or from the original solution with ether. The ethereal solution 

 left on evaporation a white crystalline solid which was sparingly soluble 

 in water, readily soluble in cold chloroform or benzol, and but sparingly 

 soluble in ligroin. When recrystallized from ligroin it formed long 

 slender lustrous prisms, which melted at 52-53°, and sublimed rapidly 

 at ordinary temperatures. It reduced argentic oxide on warming, and 

 dissolved in aqueous alkalies, forming a yellow solution. The physical 

 properties and the behavior of this substance at once recalled to our 

 minds the crystalline body melting at 77° which Hill and Sanger* 

 had obtained in small quantity from the by-products of the decompo- 

 sition of pyromucic tetrabromide by alcoholic sodic hydrate. The 

 formula of this body had been shown to be C 4 H 3 Br0 2 and an analysis 

 of the new substance left no doubt of its similar composition. 



0.1045 grm. substance gave 0.1261 grm. AgCl. 



Calculated for 



C 4 H 3 C10 2 . Found. 



CI 29.95 29.84 



This interesting body is probably formed according to the reaction 



C 5 H 2 C1 2 3 + H 2 = C 4 H 3 C10 2 + C0 2 + HC1. 



And since we found little difficulty in obtaining 40 per cent of the 

 yield which this equation demands, it will be possible to study it more 

 in detail. Unfortunately, it was discovered so late in our work as to 

 make it impossible to present the results of such a study in this paper. 

 While it would be easy for us to venture a conjecture as to its struc- 

 ture, we prefer to await the results of a future investigation. 



Trichlorpyromucic Acid. 



For the preparation of the trichlorpyromucic acid it was evidently 

 most convenient to decompose with alkalies the tetrachloride of the 

 & chlorpyromucic acid. It did not seem necessary, however, to pre- 



* These Troceerfings, xxi. 158. 

 vol. xxiv. (n. s. xvi.) 23 



