OP ARTS AND SCIENCES. 76 



of gas. The action is evidently a decomposition, and can be produced 

 at much lower temperatures, since if the tube containing the substance, 

 instead of being dipped into the heated bath as described above, is 

 gradually heated with the bath, the action takes place even below 

 120°. In fact, it can also be brought about by long-continued heating 

 in the steam bath, or partially even at 70°. It is evident, therefore, 

 that the compound has no definite melting or decomposition point, but 

 yet the temperature given at first (124°-126°) can be used as such in 

 purifying the substance, since it is essentially constant, if care is taken 

 always to heat the samples examined in the same way, 



Tiiis decomposition seemed so interesting that we examined it more 

 carefully. F'or tliis purpose a considerable quantity of the nitrite of 

 bromtrinitrophenylmalonic ester was heated in a test tube inserted in 

 an air bath, and the gaseous products of the reaction drawn through a 

 solution of baric hydrate. At 103°-108° there was a quantity of red 

 vapor given off, and a precipitate of baric carbonate formed in the 

 tubes containing the baric hydrate solution. The red vapor was recog- 

 nized by the smell as bromine, and this was confirmed by the precipi- 

 tation of argentic bromide when argentic nitrate was added to the 

 acidified filtrate from the baric carbonate. On the other hand, we 

 could not detect a trace of nitrate or nitrite with ferrous sulphate 

 and sulphuric acid. After the substance had been heated to 103°— 

 108° for three hours, the tempei-ature was raised to 125° for two 

 hours and a half, but the additional loss at this higher temperature 

 was very small. We intended originally to determine quantitatively 

 the amounts of the various products, but abandoned this idea when 

 we found that the loss was not constant, three experiments giving 

 25 per cent, 30 per cent, and 21 per cent respectively. The appear- 

 ance of the bromine, too, shows that there has been a complete decom- 

 position of a part of the substance, and therefore the volatile products 

 are of so little interest that we did not care to spend the time neces- 

 sary for the identification of the others, which must have been formed 

 in addition to the bromine and carbonic dioxide. On the other hand, 

 we were much interested in the non-volatile product of the reaction 

 left in the test tube as a fused rather viscous mass of a brownish red 

 color, in which crystals were embedded. It was purified by washing 

 several times with alcohol, which removed much of the viscous por- 

 tion, then the residue was crystallized, first from dilute, and finally 

 from common alcohol, and when pure showed the melting point 156° 

 and the crystalline form of the bromtrinitrophenyltartronic ester 

 described later in this paper. The action of heat on our nitrite, there- 



