C24 PROCEEDINGS OP THE AMERICAN ACADEMY. 



Three molecules of water of crystallization, the amount found by 

 Garzino in his barium salt, would give 6.19 per cent of water. 



IV. 0.3923 gr. of the salt dried at 120° gave 0.1112 gr. of baric 

 sulphate. 

 V. 0.2668 gr. of the salt dried at 120° gave 0.0754 gr. of baric 

 sulphate. 



Calculated for Found. 



[C B HBr,0(N0 2 ) 2 ] a Ba. IV. V. 



Barium 16.73 16.66 16.62 



The salt is yellow while it contains its water of crystallization, 

 but turns orange as it loses it, and this change takes place in a 

 desiccator over sulphuric acid, as under these circumstances it loses 

 all but an insignificant fraction of the water which it contains. 

 The dried salt absorbs water very eagerly from the air, turning from 

 orange to yellow again. It crystallizes from boiling water in clus- 

 ters of radiating needles, and is soluble in alcohol. 



The dark red filtrate from the precipitate of the barium salt of 

 dibromdinitrophenol gave upon acidification an oily precipitate, 

 which has resisted all our efforts to bring it into a state fit for 

 analysis; it is probable that this could be done by often repeated 

 fractional precipitation, but we do not think the identification of 

 the substance of sufficient importance to justify the large expendi- 

 ture of time and work necessary to provide material enough for this 

 purpose. Several analyses, which we made to determine the purity 

 of our preparations, seemed to point to the presence of a substance 

 having the composition C 6 HBr 2 N0 2 (OH) 2 , but, as at the same time 

 they proved that our products were decidedly impure, no weight 

 should be given to this indication, although the formation of some 

 such substance is to be expected from the appearance of sodic 

 nitrite among the products of the reaction. 



Sodic hydrate acts upon tribromdinitrobenzol in the same way 

 that sodic carbonate does, but somewhat more rapidly. It has ap- 

 parently no action in the cold. 



