OF ARTS AND SCIENCES. 319 



ric acid it turned from red to yellow, and a white precipitate was 

 thrown down, to which we first turned our attention. 



The white product of the reaction, which is insoluhle in water, 

 was purified by dissolving it in amnionic hydrate, precipitating the 

 barium salt from this solution by means of baric chloride, and treat- 

 ing the precipitate with alcohol, in which the barium salt of this 

 substance is soluble. The filtered alcoholic solution was evapo- 

 rated to dryness, the residue recrystallized several times from hot 

 water, and then converted back into the free phenol by treatment 

 with dilute hydrochloric acid. The free phenol was next dissolved 

 in as little hot alcohol as possible, diluted with water till a pre- 

 cipitate began to form, which was then redissolved by the addition 

 of a drop or two of alcohol, when upon cooling the substance sepa- 

 rated in good crystals. This rather long method of purification 

 can be replaced by simple crystallization of the free phenol from 

 alcohol and water in the way just described, but, if an absolutely 

 pure product is needed, the whole method described above should 

 be used. After it showed the constant melting point 194°, it was 

 dried at 100° and analyzed with the following results: — 



I. 0.1951 gr. of the substance gave 12 c.c. of nitrogen at a tem- 

 perature of 23° and a pressure of 768.1 mm. 

 II. 0.2089 gr. of the substance gave according to the method of 

 Carius 0.2787 gr. of argentic bromide. 



These analyses show that the substance is a tribromdinitrophenol, 

 and as it must have been formed from the tribromtrinitrobenzol by 

 replacing one of the nitro groups by h3'droxyl its constitution must 

 be represented by the formula CcOHBrlSrC^BriSrOoBr. It is, so far 

 as we are aware, the first tribromdinitrophenol which has been 

 made. 



To confirm the results of the preceding analyses the sodium salt 

 was made by treating an excess of the phenol with pure sodic 

 hydrate, filtering, and crystallizing from hot water, when it sep- 

 arated in long filiform yellow needles. 



0.3076 gr. of this sodium salt gave 0.0504 gr. of sodic sulphate. 



Sodium 



