512 Dr. Hofmann o« the Metamorphoses of Indigo. 



h. Properties of Dibromaniline. 



These I have not as yet very carefully studied. They re- 

 semble in many respects those of bromaniline. The crystals 

 of this body, however, have a totally different form. It does 

 not crystallize in octahedrons as the bromaniline, but in flat, 

 four-sided, rhombic prisms of considerable size, which unfor- 

 tunately present no terminal planes. 



The base is soluble in spirits of wine and yields successive 

 crops of crystals to the last drop. It is only slightly soluble 

 in boiling water, which becomes turbid on cooling, and de- 

 posits gradually fine white needles. The crystals of the base 

 melt, between 50° and 60° cent., to a dark oily fluid, which 

 frequently on cooling remains long liquid, but on agitation 

 suddenly solidifies to a crystalline mass. 



A solution of the base in acids communicates, like aniline, 

 a yellow colour to fir-wood and the pith of the elder tree. 



The compounds of dibromaniline have likewise as yet not 

 been the object of particular study. I will only mention a 

 few observations which appeared to me essential to the esta- 

 blishment of the chemical characters of dibromaniline. 



It possesses the properties of a base; its basic character is 

 however much less pronounced than that of bromaniline. It 

 dissolves in acids, and is again precipitated by alkalies. Its 

 solution in hydrochloric acid gives with perchloride of iron 

 the crystalline orange-yellow precipitate, characteristic of or- 

 ganic bases. It forms with acids crystalline salts, but these 

 compounds possess much less stability than the correspond- 

 ing salts of bromaniline. 



A solution of the base in boiling hydrochloric acid deposits 

 on cooling a salt which crystallizes in plates. 



0'2313 grm. of these crystals, precipitated with nitrate of 

 silver, gave 0'1205 grm. of chloride of silver, corresponding 

 to 13-21 per cent, of hydrochloric acid. This determination 



D , ^ N, as is seen by the 



following : — 



Theory. Experiment. 



1 equiv. Base . . . =3096*17 87'19 



1 ... CI H . . . = 435-15 12-81 13'21 



This substance is decomposed by the action of warm water. 

 The base separates from the acid and swims on the surface of 

 the fluid in the form of oily drops. This want of stability in 

 the hydrochloric compound is also seen when the base is dis- 



