Dr. Hofmann on the History of the Monamines. 189 



phosphorus-bases, now and then involves the study of reactions 

 which are scarcely comprised between the boundary lines of the 

 principal inquiries. For the sake of perspicuity, I beg leave to sub- 

 mit the results of these studies separately to the Society. 



1 . Action of Bibromide of Ethylene on Trimethylamine. 



The unexpected result obtained in the action of bibromide of ethyl- 

 ene on triethylphosphine, induced me to examine the deportment of 

 the tertiary amine-bases under the influence of the same agent. As 

 a characteristic representative of this class I have selected trimethyl- 

 amine, which may be readily procured in tolerable quantity and in a 

 state of purity. 



On submitting trimethylamine to the action of bibromide of ethyl- 

 ene, phenomena are observed which are perfectly similar to those 

 which occur in the analogous experiment with triethylphosphine. 

 On account of the volatihty of the trimethylamine, I have never 

 worked with the anhydrous base, but invariably either with aqueous 

 or alcoholic solutions. At the common temperature bibromide of 

 ethylene is only gradually acted on by an aqueous solution of trime- 

 thylamine. Frequent agitation and contact for several days are 

 necessary to complete the reaction ; addition of alcohol accelerates 

 the process ; which may be still very considerably shortened by ex- 

 posure of the mixture in sealed vessels to a temperature of from 40° 

 to 50°. To exclude complication, it is desirable to avoid a higher 

 temperature and to keep always the bromide in considerable 

 excess. 



By adopting these precautious, the mixture of the two bodies is soon 

 found to deposit a white crystalline salt, the formation of which con- 

 tinues until the liquid has assumed an acid reaction. A considerable 

 quantity of this salt is dissolved in the water ; it is therefore most 

 convenient to distil off the excess of bibromide of ethylene and to 

 evaporate the residuary liquid to dryness. The dry saline mass, 

 separated from a slightly yellowish deliquescent substance by washing 

 with absolute alcohol and once or twice recrystallized from the same 

 solvent, furnishes magnificent white needles, extremely soluble in 

 water, readily soluble in boiling alcohol, much less so in cold alcohol, 

 and insoluble in ether. This salt can be boiled with the fixed alka- 

 lies without disengaging a trace of an alkaline vapour. This deport- 

 ment renders it easy to recognize the absence of impurities. 



The composition of this substance, established by many deter- 

 minations, is represented by the formula 



C,H3 1 

 C,H,3NBr,= g«g3 U.Br. 



(C»r)'J 



This substance, whicli presents itself as bromide of trimethyl-bro- 

 methylene-ammonium, is formed by the simple union of 1 equivalent 

 of bibromide of etliylcne with 1 equivalent of the tertiary mon- 



