OF ARTS AND SCIENCES. 269 



get perfectly cool, was treated with a little alcohol, when crystals 

 separated on standing, which were purified by recrystallization from 

 alcohol, until they showed the constant melting point 123°. They 

 gave no test for bromine when heated on a copper wire, and, after 

 drying in vacuo, were analyzed with the following results : — 



I. 0.3004 gr. of the substance gave on combustion 0.5043 gr. of 



carbonic dioxide, and 0.1230 gr. of water. 

 II. 0.2392 gr. of the substance gave 1 6.8 c.c. of nitrogen at a tem- 

 perature of 25° and a pressure of 768 mm. 



Calculated for Found. 



CeHlNO^^CIKCOOC.IIs).,]^ I. II. 



Garbon 45.37 45.78 



Hydrogen 4.35 4.55 



Nitrogen 7.94 7.92 



A small quantity of this substance can also be formed in the cold, 

 and more than once some of it has been obtained in making the 

 bromtrinitrophenylmalonic ester by the process described earlier in 

 this paper (compare pages 258 and 264). 



Properties. — The trinitrophenylendimalonic ester crystallizes from 

 alcohol in long colorless prisms, terminated by a single rhombic plane 

 at a tolerably sharp angle to the sides ; less frequently, the termination 

 consists of two planes at an obtuse angle to each other, so that the 

 general effect is as if the prisms had rounded ends. They are fre- 

 quently grouped, or twinned, parallel to their long axes, so that often 

 there are two or more terminations at one end of a group. The sub- 

 stance melts at 123°; and is very nearly, if not quite, insoluble in 

 water, whether cold or boiling; essentially insoluble in ligroine ; not 

 very soluble in cold ethyl or methyl alcohol, freely in either of these 

 solvents when hot ; very slightly soluble in carbonic disulphide ; 

 soluble in ether or glacial acetic acid ; and freely soluble in benzol, 

 chloroform, or acetone. Its acid properties are not so strongly de- 

 veloped as we expected. An aqueous solution of soilic hydrate 

 turns the solid pale red, but does not dissolve it to any extent ; if, 

 however, sodic hydrate is added to its alcoholic solution, it at once 

 takes on a dark brownish red color, much browner than any of the 

 similar salts which we have studied. — in fact it would be possible to 

 recognize the salt by this color. An aqueous solution of potassic car- 

 bonate gives a very faint red color with it, which is increased, but 

 not to a great extent, by adding alcohol to the aqueous solution. The 

 action was incomplete at best ; acid sodic carbonate had no action on 



