OP ARTS AND SCIENCES. 195 



Methylpyromucic acid melts at 108-109°, and sublimes readily 

 at low temperatures. It is readily soluble in alcohol, ether, chlo- 

 roform, or hot benzol, more sparingly soluble in cold benzol, and 

 almost insoluble in carbonic disulphide. It is extremely soluble 

 in hot water, and on cooling it separates from concentrated solu- 

 tions in short, thick six-sided prisms, or in small six-sided plates 

 formed by the development of these prisms parallel to the basal 

 plane. From dilute solutions it frequently separates in feathery or 

 bladed aggregations. The solubility of the acid in cold water we 

 determined by titration with a standard solution of baric hydrate, 

 using phenolphthalein as an indicator. 



I. 22.293 grm. of a solution saturated at 20° required for neu- 

 tralization 15.3 c.c. of a solution of baric hydrate, containing 

 0.01864 grm. Ba0 2 H 2 in 1 c.c. 

 II. 19.665 grm. of a solution saturated at 20° required for neu- 

 tralization 13.55 c.c. of the above solution of baric hydrate. 



According to these determinations an aqueous solution saturated 

 at 20° contained the following percentages of acid: — 



I. ii. 



1.89 1.89 



Methylpyromucic acid is therefore decidedly less soluble in 

 water at ordinary temperatures than pyromucic acid.* 



For the further characterization of the acid we have prepared a 

 number of its salts. 



Baric Methylpyromucate, Ba(C 6 H 5 3 ) 2 . — This salt we made 

 by boiling an aqueous solution of the acid with baric carbonate. 

 The salt is readily soluble in cold water, somewhat less soluble in 

 hot water, and separates on evaporation in small colorless octahedral 



* According to Houton Labillardiere (Ann. Chim. Phys., [2.], IX. 368), pyro- 

 mucic acid is soluble in 26 parts of water at 15°. This result is confirmed by 

 approximate determinations made in this Laboratory as a guide in the prepara- 

 tion of pyromucic acid. It was found that 100 c.c. of a solution saturated at 

 17° contained 3.35 grm. of the acid, and that 100 c.c. of a saturated solution of 

 sodic chloride at the same temperature dissolved 0.60 grm. of the acid. The 

 erroneous statement made in the preliminary description of the acid (Berichte 

 der deutsch. chem. Gesellsch., XXII. 608), that it was " somewhat more readily 

 soluble in water " than pyromucic acid, was based upon rough quantitative 

 results obtained in recrystallizing from water the small quantity of the acid 

 which I then had at my disposal. — H. B. H. 



