JACKSON AND CALVERT. — METAPHENYLENE DIAMINE. 147 



inference iu regard to the composition of the base formed could be 

 drawn from these analyses, and therefore prepared the salt free from tin 

 as described above. 



After we had shown by the work just described that the three atoms 

 of bromine are removed from tribromdinitrubenzol by tin and hydro- 

 chloric acid, it became of interest to determine whether their removal 

 was due to the effect of the two nitro groups upon them. This seemed 

 a probable supposition, because it has been repeatedly observed that 

 atoms of bromine can be easily removed from the benzol ring when they 

 stand in the ortho position to nitro groups, and work done in this labora- 

 tory has proved that this tribromdiuitrobenzol is a very reactive body, 

 but on the other hand it did not seem likely that the bromine atoms 

 would be removed before the reduction of the nitro groups, as all previ- 

 ous experience seems to show that the latter are much more easily at- 

 tacked than the former. It was obvious that this point could be decided 

 by trying the action of tin and hydrochloric acid on tribromphenylene 

 diamine, for none of the bromine would be removed from this substance 

 if this action depended on the presence of the nitro groups. Accord- 

 ingly five grams of tribromphenylene diamine were mixed with tin and 

 hydrochloric acid and a piece of platinum added to increase the action. 

 In the cold no change was observed, and therefore the mixture was 

 warmed on the water bath, when, after a vigorous reaction had gone on 

 for a short time, all the organic matter dissolved. The brown clear 

 solution deposited crystals as it cooled, but disregarding these the whole 

 was treated with an excess of sodic hydrate and extracted with ether 

 repeatedly. The residue from the ethereal extracts was an oil, which 

 solidified after it had been scratched with a sharp glass rod, and then 

 melted at about 62°. There was little doubt therefore that the sub- 

 stance was metaphenylene diamine, which melts at 63°, and this view 

 was confirmed by the following observations. The substance gave a 

 white salt with hydrochloric acid soluble in water, but nearly insoluble 

 in hydrochloric acid. To a solution of this chloride bromine water 

 was added, taking care to avoid an excess ; this produced a white pre- 

 cipitate, which after recrystallization from benzol melted at 158°, and 

 was therefore tribromphenylene diamine. It follows from this experi- 

 ment (which was repeated several times) that tribromphenylene dia- 

 mine gives up all its bromine to tin and hydrochloric acid, and therefore 

 that the removal of the bromine atoms does not depend on the 

 loosening effect of the two nitro groups. 



Action of Tin and Hydrochloric Acid on Trihromhenzol and on Tri- 

 bromaniline. After we had shown, as just described, that all the bro- 



