76 Upon a Fourth Monobromplienol. 



and one molecule of monobrom -din itro -phenol, and has, there- 

 fore, the formula 2 C c H 3 Br (N0 2 ) OH. C e H 2 Br (N0 2 ) 2 Oil. 

 It can be obtained pure by precipitating the above-mentioned 

 mother-lye with hydrochloric acid, and by crystallizing several 

 times from alcohol the yellow, amorphous, and somewhat greasy 

 mass, which is deposited after a few hours. This compound is, 

 strange to say, much more stable than the one spoken of before 

 of equal molecules of monobrom-nitro and dinitrophenol. 

 Without changing its melting-point, it can be crystallized in 

 various ways from hot alcohol properly diluted ; it appears, ac- 

 cordingly, in small yellow needles united in the form of stars, 

 which color the skin and other organic substances (paper, etc.), 

 an intense yellow, as does also the above molecular combination. 

 Analysis : 



I. 0.2878 gv. gave 30.51 per cent. C, and 2.20 per cent. H. 



II. 0.1948 gr. gave 30.61 per cent. C, and 2.23 per cent. H. 



III. 0.1941 gr. gave 33.94 per cent. Br. 



(Calculation for 2 6 H 3 Br (N0 9 ) OH. C 6 H 2 Br (N0 2 ) 2 OH: 

 C = 30.90 per cent., H = 1.57 per cent., and Br. = 34.33 per 

 cent. ) 



The determination of hydrogen resulted in both cases a little 

 too high ; the cause of this is, that the copper spirals were not 

 free from hydrogen when applied, which was noticed afterwards. 



Besides these substances, I have yet to mention two nitro- 

 compounds — one of which, it is true, I obtained only once — the 

 second, however, repeated!} 7 . The former gave, according to a 

 single determination, but tolerable numbers for a monobrom- 

 mononitro -benzol ; but I rather believe that it represents a molecu - 

 lar combination. I obtained it once by treating the fourth 

 bromphenol, after the solution in an equal volume of glacial 

 acetic acid, with a mixture of nitric acid of equal volumes of the 

 acid of 1.4 and 1.2 sp. gr. It melted within five degrees (between 

 50° and 55°). and it was manifest that it changed its melting- 

 point by a further crystallization. The substance melting be- 

 tween 50° and 55° gave in the analysis the following numbers : — 



0.3328 gr. substance furnished 37.27 per cent, bromine. 



(Calculation for C 6 H 3 Br (N0 9 ) OH : Br = 36.70 per cent.) 



In respect to the variability of its melting-point, I must, how- 



