170 Proceedings of the Royal Irish Academy, 



at 135° C. Since a mixture of it with 4--'>ii(ro-o-toli/lure(hane also melted at 

 the same temperature, the two substances must have been identical. 



IV. Ethyl- o-tolylurethanc. 



Ethyl-o-tolyhuetliane, like ethyl-phenylurethane in five per cent, solution 

 in glacial acetic acid, alcohol, and carbon tetrachloride, gave with butyl 

 nitrite and acetic or hydrochloric acid, oily products from which no crystal- 

 line substances were isolated. 



V. Phenyl-henzylurethaTie. 



{a) Nitrous acid. — Five per cent, solutions of phenyl-benzylurethane in 

 glacial acetic acid, alcohol, and carbon tetrachloride, were mixed with six 

 molecular amounts of butyl nitrite and acetic or hydrochloric acid. The 

 solutions were allowed to remain at the temperature of the room for eight to 

 twelve weeks. In no case could the oily substance, finally isolated after 

 removal of the solvent, be obtained in a crystalline condition. 



(6) Nitrous fumes. — A solution of 1 gram of phenyl-benzylurethane in 

 10 COS. of glacial acetic acid was cooled in ice, and niti'ous fumes were passed 

 through it for thirty to forty-five minutes. The reddish -yellow solution was 

 allowed to remain at the temperature of the room for a couple of days, and 

 was then poured into water. The solution was decanted from the yellow 

 oily solid which had separated. The latter, on recrystallisation from alcohol, 

 gave beautiful acicular prisms which melted at 70°-71° C. A mixture of it 

 with phenyl-4'-nitro-benzylurethane melted about 60° C, while a similar 

 mixture of it and 4-nitro-phenyl-benzylurethane melted at 70°-71° C. The 

 substance was therefore 4-mtro-phenyl-l}enzylurethane. 



VI. Diphcnyhi,retlian.e. 



(a) Nitrous acid. — From solutions of diphenylurethane in glacial acetic 

 acid, alcohol and carbon tetrachloride to which nitrous acid, butyl nitrite and 

 an acid, had been added, and which had been allowed to remain at the 

 ordinary temperature for intervals up to three months, the urethane was in 

 all cases recovered unchanged. 



(b) Nitrous femes. — 1. Diphenylurethane " (2 grams) was dissolved in 

 carbon tetrachloride (20 c.cs.); the solution was cooled in iced watei', and 

 nitrous fumes were passed through it for fifteen minutes. The solvent 

 was allowed to evaporate at the ordinary temperature, and the solid was 

 recrystallised from carbon tetrachloride. It consisted of colourless acicular 

 prisms which melted at lo4^ C, and was found to consist of pure ^.-lO dinitro- 

 diphenylur ethane. 



