_COMBINATIONS of NITROGENE_
At temperature 55°, and atmospheric pressure 30.
+------+-------+--------------+---+------+------+---------+---------+
| | |100 Cubic In. | |grains| |Nitrogene| Oxygene |
| | +--------------+---+------+------+---------+---------+
|Nitro-| With | Nitrogene | | 30.04| | | |
| gene | Oxy- | Oxygene | | 35.06| | | |
| | gene +--------------+---+------+ 100 +---------+---------+
| | |Atmospher. air| w | 31.10|grains| 73.00 | 27.00 |
| | |Nitrous oxide | e | 50.20| are | 63.30 | 36.70 |
| | |Nitrous gas | i | 34.26|com- | 44.05 | 55.95 |
| | |Nitric acid | g | 76.00| posed| 29.50 | 70.50 |
| | | | h | | of +---------+---------+
| | | | | | |Nitrogene|Hydrogene|
| +-------+--------------+---+------+ +---------+---------+
| | With | | | | | | |
| | hydro-|Ammoniac | | 18.05| | 80.00 | 20.00 |
| | gene | | | | | | |
+------+-------+--------------+---+------+------+---------+---------+
No. III.
_Additional Observations._
_a._ In Res. 1st. Div. IV. Sect. III. in the analysis of nitrous gas by
pyrophorus, as no absorption took place when the residual nitrogene was
exposed to water, I inferred that if any carbonic acid was formed it
was in quantity so minute, as to be unworthy of notice. A few days ago,
I compleatly decomposed a quantity of nitrous gas by pyrophorus, when
the residual nitrogene was exposed to solution of strontian, the fluid
became slightly clouded; but no perceptible absorption took place.
_b._ If there was the least probability in any of Dr. Girtanner’s
speculations on the composition of Azote,[235] the experiments on the
exhausted capacity[236] of the lungs in Res. III. might be supposed
inconclusive. But there appears to be no more reason for supposing
that hydrogene is converted into nitrogene by respiration, than for
supposing that it is converted into water, carbonic acid or oxygene;
for all these products are evolved when that gas is respired. From
the comparison of Exp. 1 with Exp. 3, Res. iii. Div. ii. Sec. 4, it
is almost demonstrated that no ascertainable change is effected in
hydrogene by respiration. The experiment of the accurate Scheele in
which hydrogene after being respired thirty times in a bladder wholly
lost its inflammability, may be easily accounted for from its mixture
with the residual gases of the lungs.
[235] Annales de Chimie, 100; and Mr. Tilloch’s Phil. Magazine. 24.
[236] I regret much that I could not procure Dr. Menzies’s observations
on Respiration, while I was making the experiments on the capacity of
the lungs: they would probably have saved me some labor.
About a fortnight ago, I respired, after forced voluntary exhaustion of
my lungs, my nose being accurately closed, three quarts of hydrogene in
a silk bag, at four intervals, for near five minutes. After this it was
highly inflammable, and burnt with a greenish white flame in contact
with the atmosphere; but was not so explosive as before.[237]
[237] If loosely combined carbon exists in venous blood, hydrogene may
probably dissolve a portion of it when respired and become slightly
carbonated. At least there is as much probability in the supposition
that carbon in loose affinity may combine with hydrogene at 98° as that
it may combine with oxygene.
_c._ From what we have lately heard of the curious experiments of Mr.
Volta and Mr. Carlisle, it is very probable that the conversion of
nitrous gas into nitrous oxide when exposed to wetted zinc, copper
and tin, in contact with mercury, as described in Res. I. Div. V. may
in some measure depend on the action of the galvanic fluid. Whilst I
was engaged in the experiments on this conversion, Dr. Beddoes[238]
mentioned to me some curious facts noticed by Humboldt and Ritter,
relating to the oxydation of metals by the decomposition of water,
which induced me to examine the phænomena with more attention than I
should have otherwise done.—I recollect observing that some of the
wetted zinc filings in nitrous gas on the side of the jar not in
contact with the surface of mercury, were very slowly oxydated. Whilst
on the surface of the mercury where small globules of that substance
were mingled with the filings of zinc, the decomposition went on much
more rapidly; possibly through the medium of the moisture, a series of
galvanic circles were formed.
[238] Dr. BEDDOES has since favoured me with the following account of
these facts.
“Mr. Humboldt (ueber die gereizte Faser I. 473, 1797) quotes part of a
letter from Dr. Ash, in which it is said that _if two finely polished
plates of homogeneous zinc be moistened and laid together, little
effect follows—but if zinc and silver be tried in the same way, the
whole surface of the silver will be covered with oxydated zinc. Lead
and quicksilver act as powerfully on each other, and so do iron and
copper._—Mr. Humboldt (p. 474) says that, in repeating this experiment,
he saw air-bubbles ascend, which he supposes to have been hydrogene gas
from the decomposition of water—When he placed zinc simply on moist
glass, the same phænomena took place, but more slowly and later. The
quantity of oxyd of zinc upon the glass alone was in 20 hours to that
on the silver as one to three.
In a very ingenious but obscurely written tract by Mr. Ritter,
entitled, _Evidence that the galvanic action exists in organic nature_,
_8vo. Jena, 1800_—The author observes, that the care of Dr. Ash and
Mr. Humboldt that the metals should touch each other in as many points
as possible was superfluous, even if we could grant that two metallic
plates might be made by polishing, to touch in a number of points.
To shew that it was sufficient if by touching in one point only they
should form a compleat galvanic circle, he dropped a single drop of
distilled water upon the bust of a large silver coin. A piece of pure
zinc was placed with its one end on the edge of the coin, while the
other was supported by a bit of glass. The drop of water was neither in
contact with the glass nor with the point at which the metals touched.
The materials were left in this situation for four hours at the
temperature of 68°. On taking them apart, the water had become quite
milky and had half disappeared; and Mr. Ritter actually separated a
quantity of white oxide that had been produced in the experiment.
The pieces of metal were cleaned and laid together in the same manner,
only that now a piece of paper was put between the metals at their
former point of contact. In four hours first, and afterwards in ten, a
faint ring of oxide only had been produced of which the quantity could
not be estimated, nor could it be separated. In this case, the zinc
had scarce lost any thing of its splendour; in the former it had been
corroded. In many repetitions of the experiment, he found that far more
oxide was formed when the metals touched, than when they were separated
to the slightest distance by an insolating body, even air.
On exposing these apparatuses with somewhat more water to a
considerable heat for four minutes, the water in the interrupted circle
continued quite clear, while that in the other had become milk-white.
The same phænomena were presented by other pairs of metals in a degree
proportional to their galvanic activity; viz. by zinc and molybdæna,
zinc and bismuth, zinc and copper, as also with tin and silver, tin
and molybdæna, and lead and silver. The experiment with tin was
particularly decisive, for when in contact with no other metal it was
scarcely at all oxydated by water, though oxydation took place when tin
was brought into contact with silver, and both were connected at the
other end by a drop of water—What therefore took place in Dr. Ash’s
experiment, arose from an aggregation of galvanic circles of different
forms.
By the foregoing experiments, concludes Mr. Ritter, which though
capable of the most various modifications, uniformly coincide in
their main result, it is abundantly proved that _galvanic circles
can be formed of merely inorganic bodies, by whose completion there
is produced an action which ceases when the circle is opened_. The
manner in which this has been shewn, proves also that _this action can
effectuate sensible modifications in organic bodies_; and the process
by which these modifications have been effected, made it evident that
they _were not consequences of a momentary action of the circle, but
of an action that is kept up while the circle remains entire_; for the
process which brought this action under the cognizance of the senses
went on, while the circle was unbroken, and its figure not brought back
to that of a line.
It is scarce necessary to observe that the experiments here quoted, are
far from being the only ones on which the above conclusions rest.”
_T. B._
_d._ In Res. II. Div. I. it is stated, that nitrous oxide during its
solution by common water, expels about ¹/₁₆ of atmospheric air the
volume of the water being unity.
From the delicate experiments of Dr. Pearson, on the passage of the
electric spark through water, it appears however probable, that much
more than ¹/₁₆ of atmospheric air is sometimes held in solution by that
fluid,[239] possibly the whole of the air is not expelled by nitrous
oxide, owing to some unknown law of saturation by which an equilibrium
of affinity is produced, forming a triple compound.
[239] Possibly a ratio exists between the solubility of gases in water,
and the solubility of water in gases. It is probable from Mr. Wm.
Henry’s curious experiments on the muriatic acid, that the absolute
quantity of water in _many_ gases, may be ascertained by means of its
decomposition by the electric spark.
No. IV.