OF ARTS AND SCIENCES. 



73 



so small that it is not worth the amount of work necessary to free it 

 from the red viscous impurity with which it is mixed, especially as the 

 mother liquors can be used to more advantage for the preparation of 

 the bromtrinitrophenyltartronic ester made by the longer action of 

 hot nitric acid on broratrinitrophenylmalonic ester.* 



The same substance was formed wlien the bromtrinitrophenyl- 

 maloiiic ester stood in the cold with nitric acid of specific gravity 

 1.38 for three days. At first there was no visible change, but after 

 two hours the mixture began to show a red color, which increased in 

 intensity to a deep blood-red. The product was puiified in the way 

 just described, but tliis method of making it is on the whole not so 

 good as that at a temperature of 100°. 



The e.ise with which the substance breaks up under the influence of 

 heat rendered the combustion of it a matter of gre.it diffii;ulty, since 

 we encountered at one time an almost explosive evolution of gas, and 

 at another tiie formation of a partial vacuum in the tube. The latter 

 we are inclined to ascribe to the sudden absorption 1)y the plumbic 

 cbromate of the large quantity of bromine given off by the substance. 

 We finally succeeded in getting good results by spreudinj;- out the 

 weighed portion through the whole length of a long porcelain boat, 

 and then applying the heat so gradually that a layer of not more 

 than a few millimeters of ic melted at any one time. Care was also 

 taken that the temperature did not rise much above lla° until the 

 whole of the substance had been melted, after which the combustion 

 was finished in the usual way without trouble. 



The analyses led to the fallowing results : — 



I. 0.2157 gr. of the substance gave on combustion 0.2514 gr. of 

 carbonic dioxide and 0.0498 gr. of water. 

 II. 0.197"^ gr. of the substance gave 0.2310 gr. of carbonic dioxide 

 and 0.0428 gr. of water. 



III. 0.1978 gr. of the substance gave 0.2324 gr. of carbonic dioxide 



and 0.0430 gr. of water. 



IV. 0.2014 gr. of the substance gave 20.6 c. c. of nitrogen at a tem- 



perature of 24° and a pressure of 772.6 ram. 

 V. 0.1890 gr. of the substance gave 18.6 c. c. of nitrogen at a 

 temperature of 19° and a pressure of 752.8 mm. 



* On one occasion the acid mother liquors yielded by spontaneous evapora- 

 tion hirge wliite prisms, wliicli melted in the crude state at about 99°, and we -e 

 apparently somewhat soluble in water; but, althoush we have tried in many 

 ways, we have not succeeded in obtaining this substance a second lime. 



