128 Scientific Proceedings^ Royal Dublin Society. 



In another experiment fifty cubic centimetres of fuming nitric acid (sp. g. 1-52) 

 were added in small quantities to twenty-five cubic centimetres of ethyl-piienyl- 

 urethane. During the addition of the nitric acid the mixture, which tended to 

 become hot, was shaken and cooled from time to time. The dark red, turbid 

 mixture was allowed to remain overnight in a vessel surrounded by cold wafer ; it 

 was then left in a stoppered flask at the room temperature for three weeks. During 

 this time a con,siderable amount of long, felted, acicular crystals separated from 

 the orange-red solution. The crystals were drained on a porcelain sieve, and the 

 filtrate was reserved for further examination. The solid was washed with water 

 and recrystallised from alcohol, from which it separated in the form of colourless, 

 needle-shaped crystals, which melted at 1.31^-132° 0. Its melting point was not 

 affected by addition to it of 4-nitro-phenylurethane, with which it was therefore 

 identical. About seven grams of the pure solid were obtained, the mother liquid 

 containing a further quantity, which was, however, impure owing to contamination 

 by an oil. 



The acid solution referred to above, which had been separated from the crystals, 

 was diluted with water. The yellowish oil which was precipitated measured about 

 10 c.c. It was dissolved in alcohol, and the solution was allowed to evaporate at 

 the room temperature. During the evaporation nearly colourless crystals 

 separated ; these were filtered, and after recrystallisation from alcohol they melted 

 at 110°-lll'^O., and proved to be identical with 2.4-dinitro-phenylurethane. At 

 this period, however', the alcohol still contained a considerable amount of oily 

 matter, which was not further examined. 



11. — In Glacial Acetic Acid Solution. 



{a) In hot acetic acid solution. — Ten c.c. of ethyl-phenylurethane was dissolved 

 in 50 c.c. of glacial acetic acid, and four equivalent pi'oportions of nitric acid 

 (sp. g. 1'42] were added. When the solution was heated on the water-bath, the 

 mixture, which was at first yellow in colour, changed through greenish-black to 

 yellow, and at the same time brown fumes were evolved. After three or four hours 

 the evolution of the brown fumes ceased ; the mixture was then poured into water 

 and let stand overnight. When the yellow crystals which had separated were 

 filtered, washed, and recrystallised from hot alcohol, they were found to consist 

 mainly of 4-nitro-ethyl-phenylurethane, melting at 55°-56° C, with a small amount 

 of dinitro-ethyl-phenylurethane melting at 88°-89° 0. 



(b) In cold acetic acid solution. — Five solutions were prepared by dissolving 

 5 grams of ethyl-phenylurethane in 100 grams of glacial acetic acid. To these 

 solutions quantities of concentrated nitric acid, corresponding to 1, 2, 3, 4, and 5 

 molecular amounts of the acid to 1 molecular amount of the base, were added 

 respectively. The mixtures were allowed to remain in stoppered flasks at the 

 room temperature for five months in each case. 



The solutions were at first light yellow in colour, but gradually acquired a 

 greenish tint, which in turn became darker in colour, and finally, on prolonged 

 standing, again became light yellow. The colour changes were the more rapid and 

 the greenish tint the deeper, the greater the amount of the nitric acid in the 

 mixture, but otherwise there was little difference irr the behaviour of the contents 

 of the various bottles. 



At the end of five months the contents of each bottle were poured into about 

 three volumes of water, and the oily mixture was in each case shaken for some time 

 in a shaking machine. 



