THE IMIDES OF THE AROMATIC SULPHONIC ACIDS. 11 



oxide, and 0.00526 gramme, if it consisted of pure nitrogen. 

 When tested with a glowing wooden splinter, it did not rekindle 

 it into a fiarae, but the piece of wood glowed decidedly brighter 

 than in the air. It was probably pure nitrous oxide, but, while 

 being tested, it must have been mixed with a comparatively 

 large quantity of the air, so that it became too dilute to rekindle 

 the glowing wood. Moreover, a small fraction of the nitrous 

 oxide must have been dissolved in the potash, especially as a 

 small quantity of alcohol had been carried over into it by the 

 action of the pump. The number above obtained, which can, in 

 any case, be only approximately correct, must, therefore, be regard- 

 ed as rather too low. 



In order to determine the relation of the quantity of the gas 

 to that of the other products of the reaction, the residue left in 

 the tube was diluted with water and treated with an excess of 

 barium nitrate. The barium sulphate formed weighed 0.3055 

 gramme, equal to 0.04195 gramme of sulphur. Mercuric nitrate 

 solution was then added to the filtrate from the barium sulphate, 

 and the mercury dibenzenesulphimide thus formed was washed 

 and w^eighed. It was found to weigh 2.5696 grammes, equal to 

 1.9276 grammes of the free imide. 



The filtrate from mercury dibenzenesulphimide was neutralised 

 and, with view to destroying all the nitrates, was treated with 

 an excess of sodium amalgam for several days and, after removing 

 and washing the excess of the amalgam, the liquid and the 

 washings were heated with hydrochloric acid at 150°C., in a 

 sealed tube. The sulphuric acid thus formed was determined as 

 barium sulphate. It weighed 1.0733 grammes, equal to 0.1474 

 gramme of sulphur, the total sulphate sulphur, therefore, amount- 

 ing to 0.1893 gramme. The sulphur in the form of sulphonic acid, 



