452 
DE. A. W. HOFMAXN" OS THE PHOSPHOErS-BASES. 
more than twelve, diethylamine not more than eight, and, lastly, in the reaction between 
triethylamine and dibromide of ethylene the number of compounds possible under the 
most favourable circumstances is limited to four. Experiment has verified this antici- 
pation ; in the same proportion as the substitution advances in the ammonia submitted 
to the action, the number of products generated diminishes ; nevertheless, the experiment 
with triethylamine, from which I had expected the simplest and clearest solution of my 
problem, did not entirely satisfy me, inasmuch as I did not succeed in obtaining more 
than th'ee of the compounds out of ihefour which are indicated by theory. It was not 
indeed till I repeated the experiment in the phosphorus-series, using, instead of triethyl- 
amine, the corresponding phosphorus-base, that I succeeded in obtaining all the com- 
pounds, and that the results appeared as the pure expression of theory, undisturbed by 
accidental products. In its reaction with dibromide of ethylene, the shar-ply defined 
characters of triethylphosphine exhibit themselves with welcome distinctness; and in 
the products resulting from the action, the peculiar relatiorrs between monatomic and 
diatomic bases become perceptible with a degree of clearrress and generality such as I 
have never observed in any similar reaction among bodies of the nitrogerr-serdes. It is 
the smoothness of these reactiorrs which renders it desirable to commence an accorrrrt of 
a more general investigation of the diatomic bases ■v\dth a descrdptiorr of the bodies 
belonging to the phosphorus-series. 
ETHYLENE-GEOUP. 
Action of Dibeomide of Ethylene on Teietiiylphospiiine. 
Wherr these two bodies are brought together in quantities not too lai'ge, the hquid 
becomes turbid, but no rise of temperature takes place to indicate the occun-ence of 
chemical action. The mixture, after being left to itself for a few hours, deposits white 
crystals, the formation of which continues till the entire liquid is converted into a white 
saline mass. If the mixture be even gently heated, the crystallization takes place 
instantaneously, and a violent reaction sets in, which is very apt to project a portion of 
the resulting salt from the vessel. In operating on rather a large scale in vessels fiUed 
with air, the heat evolved on agitation, in consequence of the oxidation of the phos- 
idiorus-base, is often sufficient to start the reaction. 
In preparing considerable quantities of the white crystals, I have therefore found it 
convenient to add to the triethylphosphine twice its volume of ether, to mix the etliereal 
solution with the dibromide of ethylene in a flask filled with carbonic acid gas, and to 
heat the mixture in a water-bath, the flask being provided with an inverted cooling 
apparatus, so that the vapours which escape may be condensed and returned. Or, the 
mixture of triethylphosphine, dibromide of ethylene and ether may be introduced into 
long tubes previously drawn out, and the tubes, after sealing, be immersed for some hours 
in boiling water. As the value of dibromide of ethylene is trifling in comparison with 
