OF ARTS AND SCIENCES. 343 



was found to contain considerable unaltered tetrachloride. That 

 portion which boiled above 140° under 16 ram. pressure was there- 

 fore redistilled under ordinary pressure and the distillate again frac- 

 tioned in vacuo. After repeated distillations we found that the portion 

 which boiled between 118° and 123° under 16 mm. pressure partially 

 solidified on cooling, and that a few crystals were also formed in the next 

 lower fraction. These fractions were therefore strongly cooled and the 

 crystalline solid removed by filtration and the liquid portions further 

 distilled. The solid thus obtained proved to be the ethyl ether of the 

 new x dichlorpyromucic acid melting at 197-198°, which we shall 

 presently describe. When no more of this crystalline ether could be 

 obtained by cooling, the liquid fractions were saponified by alcoholic 

 sodic hydrate, the acids liberated by hydrochloric acid and separated 

 through their calcium and barium salts. From the fraction boiling 

 below 110° (16 mm.) we obtained chiefly 8 chlorpyromucic acid 

 melting at 176-177°, although it yielded also a small quantity of 

 (38 dichlorpyromucic acid, which was readily isolated by means of its 

 sparingly soluble barium salt. The fractions 110-118° and 118-123° 

 apparently consisted chiefly of the ethyl ether of j3d dichlorpyromucic 

 acid, but the latter necessarily contained also a small amount of the 

 crystalline ethyl % dichlorpyromucate held in solution. The two 

 dichlorpyromucic acids could readily be separated through the differ- 

 ent solubilities of their calcium salts, the calcic (38 dichlorpyromucate 

 like the calcium salt of the corresponding bromine derivative being 

 very sparingly soluble in water. From 123° to 130° but an insignifi- 

 cant fraction was collected and the fraction 130°-153° consisted in 

 part at least of unaltered ethyl pyromucic tetrachloride, from which 

 j3y dichlorpyromucic acid was obtained. 



100 grin, of ethyl pyromucate yielded us 197 grm. of the tetrachlo- 

 ride and from this we obtained the following weights of pure products : 



be materially increased by filling a few inches of the stem of the distilling flask 

 with glass beads, and thus combining the Hempel's column with the vacuum 

 distillation. The beads were supported upon a perforated disk of platinum foil 

 slipped over the capillary air tube and held in place by a slight enlargement of 

 the tube. The thermometer was then raised to the proper line by a short bit 

 of small glass tubing dropped into the air tube. Ilantzsch (Ann. Chem. u. 

 Pharm., ccxlix. 57) has used with advantage for distillation under ordinary 

 pressure a long necked boiling flask whose stem is partially filled with beads 

 supported upon a platinum foil forced into the neck. We have for a long time 

 used such a Hempel's column, but have supported the beads conveniently upon 

 a glass bulb which nearly fills the stem and whose sealed neck is long enough 

 to rest upon the bottom of the flask. 



