OF ARTS AND SCIENCES. 207 



The decomposition of mucochloric acid into dichloracrylic and formic 

 acids, under the influence of alkalies, is much more neatly accomplished 

 than the corresponding reaction with mucobromic acid. Under ordi- 

 nary conditions, but little hydrochloric acid is split off, and the yield 

 of dichloracrylic acid is nearly 90 per cent of that required by the 

 equation, — 



C,H,C1,03 + 11,0 = C3H,C1,0, + CH^O,. 



We never have noticed in the preparation of dichloracrylic acid 

 either chlorpropiolic acid or any compound corresponding to that 

 which brompropiolic acid forms with dibromacrylic. We usually have 

 dissolved mucochloric acid in quite an excess of potassic hydrate, 

 allowed the solution to stand for a short time, acidified with hydro- 

 chloric acid, and extracted with ether. The dichloracrylic acid left on 

 evaporation of the ether may be purified by melting it several times 

 with a little water. When dried over .sulphuric acid it gave the fol- 

 lowing results on analysis : — 



I. 0.5280 grm. substance gave 0.4894 grm. CO, and 0.0720 grm. 



HoO. 

 II. 0.3670 grm. substance gave 0.3399 grm. CO, and 0.0477 grm. 

 H,0. 



III. 0.1037 grm. substance gave 0.2123 grm. AgCl. 



IV. 0.2674 grm. substance gave 0.5420 grm. AgCl. 



Calculated for CgHjCljOj. Found. 



ni. IV. 



C 25.54 



H 1.42 



CI 50.36 50.62 50.10 



This dichloracrylic acid forms small rhombic prisms which vol- 

 atilize rapidly on exposure to the air. It is readily soluble in water, 

 alcohol, ether, or chloroform, and it also dissolves freely in boiling 

 benzol, carbonic disulphide, or ligroin. It melts at 85-86°, and, when 

 solidified by quick cooling, melts again at the same temperature. The 

 yS dichloracrylic acid of Wallach, on the other hand, melts at 76-77° 

 and its melting point falls to 63-64° when melted and suddenly cooled. 



Argentic Dichloracrylate, AgCgHCl202. The silver salt was precip- 

 itated in the form of fine felted needles on the addition of argentic 

 nitrate even to a dilute solution of the acid. The salt was quite 

 stable and could be recrystallized from hot water without any marked 

 decomposition. 



