404 PROCEEDINGS OP THE AMERICAN ACADEMY. 



Picrylmalonic Ester, C6Ho(NO,)3CH(COOC2H5)2. 



Although in our earlier experiments we prepared this substance 

 through its sodium salt on account of the discouraging statements of 

 Dittrich, we soon found that this was unnecessary, as the substance 

 could be purified directly without difficulty, and in all our later work 

 we have adopted this direct method, which we are about to describe, 

 as it is much more convenient than the method of purification by means 

 of the sodium salt. To prepare the picrylmalonic ester we proceeded 

 according to the method described under Sodium Picrylmalonic Ester, 

 until by the addition of water the product had been divided into an 

 aqueous and a benzol solution. The aqueous solution after acidifica- 

 tion with dilute sulphuric acid was allowed to stand until the oily pre- 

 cipitate bad separated completely from the mass of the liquid ; part 

 of it settled, part floated on the surface, and even during this com- 

 paratively short standing the floating part was converted into crystals, 

 which could be used to promote the crj'stallization of the larger quan- 

 tity on the bottom of the beaker. This solidification of the main 

 portion of the oily product was effected without difficulty by cooling 

 with running water, one of the crystals from the surface of the water 

 laeing added if necessary ; and the solidified product, after washing with 

 cold water, was crystallized from alcohol. The benzol solution, which 

 had been separated from the aqueous solution, was acidified with dilute 

 sulphuric acid, and allowed to evaporate spontaneously, when it fur- 

 nished a rather large additional quantity of the oily product, which 

 however, did not solidify so easily as that obtained from the aqueous 

 portion, since it was necessary to allow it to stand for three or four 

 days with occasional stirring in order to bring it into a crystalline 

 condition. It was then pressed between layers of filter paper, which 

 removed an oily impurity, after which it was mixed with the crystals 

 obtained from the aqueous liquid, and the whole purified by crystalli- 

 zation from alcohol until it showed the constant melting point 59°, 

 when it was dried in a desiccator, and analyzed with the following 

 results : — 



I. 0.2707 gram of the substance gave 28.6 c.c. of nitrogen at a 

 temperature of 25° and a pressure of 757.4 mm. 

 II. 0.2565 gram gave 25.9 c.c. of nitrogen at a temperature of 22° 

 and a pressure of 755.8 mm. 



Nitrogen 



