The agreement of the theoretical value with the experimentally 
found one is not as good as could be desired and it is therefore quite 
possible that despite the careful distillation a trace of some other 
homologue of maleie anhydride remained admixed to the examined 
product. These impurities cannot however amount to much, in fact 
the merest traces may have the influence stated. 
The conversion of the anhydride into the imide was carried out 
in the manner deseribed in our former communication. We got it 
this time in the form of white needles melting exactly at 560, by 
erystallising the raw product from ligroin several times. 
The reduction with zine dust at high temperatures in a current 
of hydrogen took place rapidly and the fumes produced were 
carried by the hydrogen current into a flask containing well coo- 
led ether. The ethereal solution, which was coloured slightlv yellow 
was next shaken for some time with an aqueous solution of ben- 
zenediazoniumehloride. The colour of the ether turned at once red- 
dish brown. The ethereal solution was next separated and treated 
with a small quantity of eone. hydrochlorie acid, the latter turned 
bright cherry red, whereas the ether retained a brown colour; the 
latter was poured off and replaced by new small quantities of ether 
and shaken as long as it took up any of the brown eolouring mat- 
ter. Next the solution in hydrochloric acid was diluted with water, 
the acid neutralized by adding sodium hydrate and the colouring 
matter taken up in ether. The ethereal solution. after washing it 
repeatedly with small quantities of water in order to remove the 
superflous alkali, was finally treated with a small quantity of di- 
lute hydrochlorie acid. The formerly bright red colour changed to 
a more bluish shade and in the hope to get the azobody in the 
erystallized state the acidulated ethereal solution was left to stand 
for some time. No erystallisation however took place. After removing 
the ether by evaporation a red mass remained which appeared greenish 
in reflected light. It was dissolved in alcohol, some sodium hydrate 
and water added and the whole shaken up with ether. The ethereal 
solution examined in the spectroscop revealed the haemopyrroline- 
disazo-dibenzene spectrum. consisting of two bands placed in exactly 
the same position as the bands of the disazo eolouring matter na- 
med. The acidulated ethereal solution showed a spectrum correspon- 
ding exactly to the spectrum of haemopyrroline-disazo-dibenzene- 
hydrochloride. 
