142 Scientific Proceedings, Royal Dublin Society. 



In every case, on the addition of the nitric acid, heat was evolved, increasing as 

 the amount of nitric acid added increased, and after a short time a white substance 

 began to separate in leaflets. The amount of substance separating, moreover, 

 increased with the amount of acid added. The only change effected on allowing 

 the bottles to remain at the temperature of the room for two months was the 

 appearance of a brown colouration in the solution, and a green or brown one in 

 the substance. 



At the end of two months the solution in each bottle was filtered from the 

 solid, which latter was found to be the same in every case. On drying in air the 

 substance melted with decomposition at 131° 0. The addition of phenylurea to it 

 lowered the melting point considerably. When treated with cold water it melted at 

 146"^ C, and an addition of phenylurea to this did not affect the melting point. 

 The water used was found to contain nitric acid. The original substance gave, 

 therefore, on treatment with water, phenylurea and nitric acid. 



To a weighed quantity of the colourless, freshly prepared substance water was 

 added and then titrated with standard alkali. As a mean of several consistent 

 determinations it was found that 1 g. of the substance required for complete 

 neutralization 75-3 c.c. of 0-0877 N alkali, 



Corresponding to, therefore, 31-66 p.c. of nitric acid. 



C0H5 . NH . CO . NH, . HNO3 required 31-66 p.c. of nitric acid. 



The substance was, therefore, the mononitrate of phenylurea. 



Phenylurea nitrate is a white crystalline substance, separating from glacial 

 acetic acid as leaves, and melting with decomposition at 131° C. It is soluble in 

 acetone and alcohol, less so in ether and acetic acid, and almost insoluble in 

 chloroform and carbon tetrachloride. It has previously been described by Pickard 

 and Kenyon {loc. cit.). 



The solutions from each of the bottles were diluted with water, when no 

 separation occurred, and almost neutralized with sodium carbonate. In the case 

 of the bottles with one, two, and four molecular amounts of nitric acid no 

 separation occurred, but in the case of that with six molecular parts of nitric acid 

 about half a gramme of a dark brown substance was got, but from which no 

 crystalline compound was obtained. From the almost neutralized solutions 

 unchanged phenylurea was recovered in all cases by evaporation to dryness, and 

 subsequent extraction with alcohol. 



(b) Alcohol. — Pive grammes of phenylurea were treated with one, two, four, 

 and six molecular amounts of nitric acid, and allowed to remain at the temperature 

 of the room for two months. In every case the solution became yellow, and gave 

 the nitrate of phenylurea after shaking with barium carbonate, filtering, and 

 allowing to evaporate. 



(c) Carbon tetracJiloride. — Phenylurea (5 g.) was suspended in carbon tetra- 

 chloride and treated with one, two, four, and six molecular parts of nitric acid. 

 The solutions were examined after remaining two and a half months at the 

 temperature of the room. 



(1) The bottle containing one molecular amount of nitric acid had a yellow 

 solid in suspension and a yellow solution. The solid was phenylurea nitrate, and 

 from the solution a trace of a red oil, which gave no crystalline compound, was 

 obtained. 



(2) The bottle containing two molecular amounts of nitric acid gave a yellow 

 solid, melting with decomiDosition from 80°-90'^ C, and a yellow solution, which 

 contained only a little red oil. The solid was extracted with hot benzene, which 

 on cooling deposited a small quantity of colourless needles of phenylurea nitrate. 



