WHICH NITROGEN IS SUBSTITUTED EOR HYDROGEN. 
699 
watch-glass over sulphuric acid, which, however, turn red on keeping, owing to a partial 
decomposition. 
Compound of Hydrate of Silver with Diazobromobenzol , 9 6 H 3 BrN 2 , AgHG. 
This body is obtained as an almost white insoluble precipitate, very similar to the 
hydrate of silver with diazobenzol. I abstain from describing any more of the com- 
pounds of diazobromobenzol with metallic hydrates, since they entirely resemble the 
corresponding diazobenzol-compounds in every respect. 
Diazobromobenzol , € 6 H 3 Br N 2 . 
This compound is obtained in slender, bright-yellow needles by adding weak acetic 
acid to the compound of hydrate of potassium with diazobromobenzol, or as a bright 
yellow amorphous precipitate on the addition of dilute potassa to the aqueous solution 
of the nitrate of diazobromobenzol. In either case it is necessary to remove it speedily 
from the mother-liquor, and to dry it rapidly over sulphuric acid. 
Diazobromobenzol is an exceedingly dangerous compound ; for the slightest pressure, 
or even touch with a rough object, causes it to go off in a fiery explosion almost exceed- 
ing in violence that of the nitrate of diazobenzol. Although much more stable than 
diazobenzol, it can, however, be kept only for a short time in a perfectly unchanged 
condition. After being kept for some time, a reddish-brown residue is left, which no 
longer explodes even on heating, and it seems that the nitrogen has been gradually 
eliminated. Ether dissolves diazobromobenzol and causes a violent evolution of gas, 
frequently of such intensity as to give rise to explosions. When freshly prepared, this 
body is soluble in caustic potassa as well as in mineral acids, with formation of the 
previously-described saline bodies. 
COMPOUNDS OP DIAZOBROMOBENZOL WITH AMIDO-COMPOUNDS. 
Diazobromobenzol, like diazobenzol, can enter into combination with amido-bases and 
amido-acids. Since, however, these new bodies possess absolutely no fresh chemical 
interest, but resemble in every respect the amido-compounds of diazobenzol, it may 
suffice to mention a few only, as briefly as possible. 
Diazo-ami dobromobenzol, 
separates in yellow needles or small plates when a concentrated aqueous ' solution of 
nitrate of diazobromobenzol is treated with an alcoholic solution of bromaniline. This 
compound was obtained by me on a former occasion * by the action of nitrous acid upon 
alcoholic aniline. 
It needs no further proof that both methods furnish a product of identical properties. 
* Annalen der Chem. und Pharm. Bd. cxxi. p. 273. 
MDCCCLXIV. 5 A 
