1310.] 
metals from the fixed alkalies, he States, 
that the generality of enlightened che- 
mists who have repeated the experi- 
ments on potash and soda, have express- 
ed themselves perfectly satishied both 
with the facts and the conclusions drawn 
from them. As exceptions, he notices 
the opinions of Gay Lussac, Thenard, 
and Ritter, who are willing to suppose 
that potassiura and sodium are compounds 
of potash and soda, with a portion of 
hydrogen. The argument on which 
MM. Gay Lussac and Thenard depend 
is this: they say, that they heated 
potassium in ammonia, and that they 
found that a considerable quantity of 
ammonia was absorbed, and hydrogen 
produced, and that the potassium be- 
came converted into an olive-coloured 
fusible substance; by heating this sub- 
stance strongly, they obtained three- 
fifths of the ammonia again, two-fifths as 
ammonia, one-fifth as hydrogen and ni- 
trogen; by adding a little water to the 
residuum, they procured the remaining 
two-fifihs, and found in the vessel in 
which the operation was carried on, no- 
thing but potash. Again, it is stated, 
that by treating a new quantity of metal 
with the ammonia disengaged from the 
fusible substance, they again obtained 
hydrogen and an absorption of the am- 
monia; and, by carrying on the opera- 
tion, they affirm, that they can procure 
from a given quantity of ammonia more 
than its volume of hydrogen. 
Whence, they ask, can the hydrogen 
proceed ?—Shall it be admitted that it’ 
is from the ammonia? but this, say they, 
is impossible; for all the ammonia is 
reproduced. It must then come from 
the water which may be supposed to be 
in the ammonia, or from the metal itself, 
But the experiments of M. Berthollet, 
jun. prove that ammonia does not con- 
tain any sensible quantity of water, 
Therefore, say they, the hydrogen gas 
must be produced fromthe metal; and 
as, when this gas is separated, the inetal 
is transformed into potash, the metal 
appears to be nothing more than a com- 
bination of hydrogen, and that alkali,” 
Mr. Davy controverts this statement, 
affirming that the results of numerous 
“experinents ¢onducted in the presence 
of members of the Royal Society, ave, 
when the processes are conducted with 
‘accuracy, totally different from what the 
French chemists assume. ‘* In propor- 
tion,” says he, ** as more precautions are 
taken to prevent moisture from being 
* 6ommunicated to it, so, in proportion, is 
Proceedings of Learned Societies. 
* 
351 
less ammonia generated; and I have 
seldom obtained as much as 7 of the 
quantity absorbed. And I have never 
procured hydrogen and nitrogen, in 
the propertions in which they exist im 
ammonia; but there has been always aw 
excess of nitrogen.” 
He now gives an account of other 
processes conducted with the most scru= 
pulous attention ; and observes, that inall 
experiments of this kind, a considerable 
quantity of black matter, separated du- 
ring the time the potassium in the tube 
was made, to act upon water. 
This substance was examined. It was 
in the state of a fine powder. It had 
the lustre of plumbago ; it was a conduc- 
tor of electricity. When it was heated, 
it took fire at a temperature below igni- 
tion; and after combustion, nothing ree 
mained but minutely divided platina. 
Texposed some of it, says he, to heat in 
a retort, containing oxygen gas; there 
was a diminution of the gas; anda small 
quantity of moisture condensed on the 
upper part of the retort, which proved to 
be mere water. 
I made two or three experiments, with 
a view to ascertain the quantity of this 
substance formed, and to determine 
more fully its nature. I found that ia 
the process in which from 8 to 4 grains 
of potassium were made to act upon ame 
monia in a vessel of platina, and attere 
wards. distilled in contact with platina, 
there were always from 4 to 6 grains of 
this powder formed; but I have advan= 
ced no further in determining its nature, 
than in ascertaining that it is platina 
combined with a minute quantity of mat. 
ter, which affords water by combustion 
in oxygen. 
In the processes on the action of pot- 
agsium and ammonia, there is always a 
loss of nitrogen, a conversion of a por= 
tion of potassium into potash, and a pro. 
duction of hydrogen. When copper 
tubes are employed, the hydrogen bears 
a smaller proportion to the witrogen, 
and more potassium is revived. 
In these experiments, in which platina 
has been used, there is little or no losg 
of potassium or nitrogen; but a loss, 
smaller or greater, of hydrogen, 
He then describes an experiment on 
the action of sodium on ammonia with 
the same precautions. He took 3 #5 
grains of sodium, and found that it abe 
sorbed 9'1of amuonia, and produced 
45 of hydrogen, and the fusible sub- 
stance, which was very similar to that 
of potassium distilled, did not give A, of 
t | Cite ais 
