336 PROCEEDINGS OP THE AMERICAN ACADEMY 



tions failed to raise this melting point. Analysis showed this acid to 

 be a dichlorpyromucic acid. 



I. 0.4235 grm. substance gave 0.51 35 grm. C0 2 and 0.0455 grm. H 2 0. 

 II. 0.2332 grm. substance gave 0.3695 grm. AgCl. 

 III. 0.2195 grm. substance gave 0.3490 grm. AgCl. 



Calculated for Found. 



C S H 2 C1,0 3 . I. II. III. 



C 33.15 33.07 



H 1.10 1.19 



CI 39.22 39.16 39.31 



The acid, which proved on subsequent investigation to be the 

 (3y dichlorpyromucic acid, is sparingly soluble in cold water, readily 

 in hot, and crystallizes as the solution cools in finely felted needles. 

 It is readily soluble in alcohol, ether, or in hot benzol ; in cold benzol 

 it is sparingly soluble and crystallizes from it in short prisms. In hot 

 chloroform it is also readily soluble, sparingly soluble in the cold. 

 The ready purification of this acid by recrystallization rendered it 

 improbable that any sensible amount of an isomeric acid was formed 

 with it. The most patient search has failed to show the formation of 

 such a product in appreciable quantity, and from pure ethyl pyromucic 

 tetrachloride almost pure /3y dichlorpyromucic acid is obtained at once. 

 The yield of pure acid ordinarily obtained from pyromucic ether is not 

 wholly satisfactory, since it amounts to about 50 per cent of the weight 

 of ether taken, or about 39 per cent of the theoretical amount. 



The solubility of the acid in cold water we determined as usual. 

 A weighed quantity of a solution of the acid saturated at 19.5° was 

 boiled with baric carbonate and the barium dissolved precipitated by 

 sulphuric acid. 



I. 36.2505 grm. solution saturated at 19°.5 gave 0.0619 grm. BaS0 4 . 

 II. 35.6546 grm. solution saturated at 19°.5 gave 0.0615 grm. BaS0 4 . 



According to these determinations, the solution saturated at 19°. 5 

 contains the following percentages of acid : — 



i. ii. 



■ 0.27 0.27 



Baric fiy Dichlorpyromiicate, Ba(C 5 HCl 2 3 ) . 3 H 2 0.* — The barium 

 salt may be most conveniently prepared by precipitating a solution of the 



* We have already referred to the brief description of the &y dichlorpyro- 

 mucic acid published by Denaro in the Gazzetta Chimica (xvi. 333), and have 

 asserted that the analyses of the two salts which he describes are not worthy of 

 confidence. In support of our assertion we append his results in full, together 



