394 
DR. A. W. HOFMANN’S RESEARCHES INTO THE 
from which they diifer only by containing methyl, ethyl and amyl in the place of 
hydrogen, and exhibiting a deportment which agrees much better with the anti- 
cipated character of such compounds as suggested by analogy. Here we find a very 
marked difference between the properties of the compound ammonia, and those of 
the ammonium-oxide belonging to it ; in the latter, we observe no longer any feature 
which could possibly betray the presence of the former ; all their habits, volatility, 
odour, taste, &c. are totally changed ; there is a difference between the two groups 
which is not inferior to that between ammonia and potassa. The solutions of the 
new oxides may be boiled for hours without the slightest quantity of the correspond- 
ing ammonia being disengaged; several of these oxides, containing more or less water 
of constitution or crystallization, may actually be obtained in the dry state. It is evi- 
dent that the arguments mentioned above, as adduced in refutation of the ammo- 
nium-theory, cannot well be raised against the compound ammoniums. But who 
could deny the parallelism of these substances with the Berzelian type, — with the 
oxide of ammonium ? 
Again, many have found it difficult to conceive, that in the combination of am-, 
monia with hydrochloric or hydrobromic acid, the hydrogen of the latter should leave 
the chlorine and bromine, for which it is known to possess so powerful an affinity, in 
order to unite with ammonia converting it into ammonium. And they were the less 
inclined to admit of such a disposition of the elements, as every day’s experience 
showed that the alleged chloride or bromide of ammonium was incapable of ex- 
changing oxygen for chlorine or bromine, without losing the additional equivalent of 
hydrogen again in the form of water. In other terms, the decomposition of sal-am- 
moniac, by lime, into chloride of calcium, ammonia-gas and water, induced them to 
consider this salt as a compound of ammonia and hydrochloric acid ; for in the con- 
ception of the ammonium-theory we should have to assume in this decomposi- 
tion two consecutive changes, the transformation of the chloride into oxide, and 
the subsequent splitting of the latter into ammoniacal gas and water, I readily 
admit that the latter view is less simple, but I am inclined to think that this slight 
inconvenience is altogether overruled by the general advantages of the ammonium- 
theory, especially for the purposes of instruction, by the facility with which it ac- 
counts for all phenomena of transposition and substitution, and by the simple expla- 
nation it gives of the isomorphism of the potassium- and ammonium-compounds, which 
will always be the firmest foundation of this theory. On the other hand, we have 
to inquire which of the two views comes nearest to truth, and here a comparative 
consideration of the deportment exhibited by the compound ammoniums may be of 
some interest. In many respects their properties are more clearly pronounced ; and 
their behaviour is explicit and unequivocal in those very points in which the typical 
ammonium leaves room for speculation. In the combination of triethylamine with 
bromide or iodide of ethyl, it is no longer a matter of doubt whether the ethyl leaves 
the iodine in order to unite more intimately with the triethylamine, for we see that 
