Bohnenberger has arrived relative to the barometer: i. The surface
of mercury in a tube 14.5 lines in diameter, is slightly rounded at
the edge; but, at the distance of two lines from the glass, capillary
depression disappears, and the surface is level. ii. The mercury in
a tube 5.8 lines in diameter is convex over the whole surface, the
depression being .035 of a line. iii. The depression is generally
less in a vacuum than in the air, so that a syphon barometer gives
results too high, and the more so as the tube is smaller. iv.
Barometers constructed with tubes five lines in diameter, do not
require tapping to cause them to assume their proper height; and
comparatively slight blows easily make the mercury rise too high in
tubes of a smaller diameter.—_Annal. der Phys. und Chem._
12. _Easy Method of reducing Barometrical Observations to a Standard
Temperature, by_ S. Foggo.—The expansion of mercury deduced by the
different philosophers who have examined it, is given below; omitting
the results of Sir G. Shuckburgh, as being rather too far from the
mean of the others.
Expansion of mercury, from 32° to 212° F.
De Luc 1-56th }
Lavoisier and Laplace 1-55.22th }
Halstrom 1-55th } mean, 1-55.43th.
Dulong and Petit 1-55.5th }
[p459]
For 1° of Fahrenheit’s scale, this is equal to 1/9977.4, or
.00010023: which may be called one ten-thousandth, without the most
trifling error in practice. The barometric column may, therefore, be
reduced to the standard temperature of 32° F. by the following simple
rule, which will make a table unnecessary. _Before the first three
figures of the observed height place two cyphers, multiply by the
temperature of the mercury −32°, and subtract the product from the
observed height_. Example; barometer 30.597, temperature of mercury
74°.
74° − 32° = 42°.00305 × 42 = .128 and 30.597 − .128 = 30.469 the
correct height.
When the temperature of the mercury is lower than 32°, the
temperature is to be subtracted from 32°, and the product, obtained
as before, is to be _added_ to the observed height. Thus, let the
barometer be as before, and the temperature 15°: then 32° − 15° =
17°; .00305 × 17 = .052, and 30.597 + .052 = 30.649, the correct
height.—_Jameson’s Journal_, 1827, p. 378.
13. _Diamond Lenses_.—I see by the last number of the Journal of
Science and the Arts, that Mr. Varley has made a Diamond Lens, and
also a single microscope with such motions as enable the observer to
follow an animalcule in a diagonal direction. It is very odd, but
this is precisely my plan for a microscope, which I drew up about
four years ago; and as I could not get any optician to undertake it,
I sent it to the Society of Arts, and recommended them to offer a
premium for the best diamond lens, but they returned it. I have had
a microscope of this sort (made by W. and S. Jones, Holborn) about a
year and a half, and it answers the purpose completely; as a person
not at all used to microscopes may use a lens of 1/60 inch focus
and find a small object with it, and bring any part of it into the
field of view with the greatest facility, and follow the motions of
an animalcule in a diagonal direction. There are some alterations
and improvements, which I have since made, that have rendered it a
very complete microscope; a drawing of which I could send you, if you
think it would be acceptable.
I am, Sir, yours, &c.
_Tringham, Norfolk, July_ 9_th_, 1827. G. DAKIN.
14. _Sapphire Lenses for Single Microscopes_.—As it may justly
be feared that, notwithstanding the incontestable superiority
of diamond lenses, the cost and difficulty attendant on their
production will enhance their value beyond the reach of the public,
Mr. A. Pritchard, No. 18, Pickett Street, has applied himself with
indefatigable perseverance to the formation of _Sapphire Lenses_.
The valuable experiments of Dr. Brewster have determined that the
sapphire possesses a stronger refraction than any other substance
capable of giving a single image (diamond excepted), [p460] while
its dispersive power is only 0.026 compared to water as 0.035. Thus
if a sapphire is ground in the same tool which will form a lens
of glass of the 1/60 inch focus, it will come out about the 1/100
inch focus; being almost double the power of the glass in linear
amplification, and more than double in superficial; in which latter
mode of estimation the powers of the glass and sapphire may be rated
at 360,000 to 1,000,000. The faint blue tinge of the sapphire is not
felt in thin small lenses formed of this substance, which thus come
next in order to diamond ones, and form an excellent _pis aller_ for
those who cannot come at the latter. Many of our first microscopists
are already in possession of them, and have honoured them with their
unqualified approbation.
There is a property possessed by small single lenses formed by
precious stones, which is worthy of being commented on: viz. They
can be burnished fast into brass rings, and thus safely cleaned and
removed at pleasure from one setting to another. The cohesion of
glass is too slight to permit this operation, during which it is
almost sure to burst into shivers.—C. R. G.
15. _On a Method of Securing and Preserving the Rowing Pins in
Boats_.—Dear Sir,—To remove a petty inconvenience of hourly
occurrence, by some simple contrivance, is often productive of a
greater mass of advantage than an invention of greater splendour, and
of apparently more extensive utility.
[Illustration]
In the accompanying drawing, you have a plan for preserving that
indispensable requisite in a boat, the towels, or rowing pins; the
loss of which is not only very teasing, but often productive of
serious inconveniences; while the practice of stealing them from
each other forms a constant source of petty depredations, leading to
perpetual quarrels among seamen in harbours. He who has been detained
the better part of a day in the island of Sky, till half [p461] a
dozen of these pins could be procured, well knows how to value that
trifle, the neglect of which has caused the loss of his voyage, and
might have led to that of his boat and his life also.
Fixed towels cannot well be used when boats are to be hoisted in
alongside, as they are subject to be broken; and they are often
inconvenient in getting in water casks, as well as in many other
cases. Hence, pins capable of being unshipped are preferable. These
are frequently lost, and the want is not always discovered till it
cannot be replaced; or else it is not replaced without loss of that
time which is often so valuable at sea. Very often, also, the delay
of even a minute is rendered inconvenient or even dangerous; when the
boat is dragging alongside by the painter in a heavy sea, and the
vessel is either drifting or standing on.
The drawing requires little explanation. By pulling at the lower pin,
the two upper are fixed at once, and on being unshipped they hang
secure from loss; while the lower one serves us a spare towel, should
any be broken. As not one boat in twenty thousand is provided with
this invention, which is indeed scarcely known, it will not perhaps
be found undeserving a place in your Journal.—
I am, &c. J. M.
16. _Cold Injection for Anatomical Preparation_.—If a mixture of
varnish and vermilion has a small quantity of water mixed with it,
it soon sets and becomes hard. This affords an excellent composition
for anatomical injection, being very beautiful and very penetrating,
(so much so, that it frequently returns by the veins,) and requiring
no heat to be applied to the subject. The writer of this article
frequently had, in the course of his medical education, the office
of preparing this injection, of which he has, however, unfortunately
forgot the proportions, and the particular nature of the varnish. It
was, he thinks, a spirit varnish; the water was not mixed until the
instant the injection was wanted, when it was well worked up with the
syringe, and immediately thrown in; in the course of a night it would
have set beautifully. This particular kind of injection was invented
by an American anatomist of the name of Ramsay, and preserved as a
valuable secret by him for the exclusive use of his own dissecting
room. The proportions, &c. of the ingredients will soon be attained
by a few experiments.
II. CHEMICAL SCIENCE.
1. _Extraordinary Experiments on Heat and Steam by_ Mr. Perkins.—“I
discovered that a generator at a certain temperature, although it had
a small crack in it, would not emit either water or steam. This fact
I mentioned to a very scientific friend, who questioned its accuracy,
and to convince him I tried the experiment; but he concluded that the
expansion of the metal must have closed the fissure. To remove every
doubt, I proposed to drill a small [p462] hole through the side of
the generator, which was accordingly done. After getting the steam up
to a proper temperature, I took out the plug, and although we were
working the engine at thirty atmospheres, nothing was seen or heard
to issue from the plug-hole; all was perfectly quiet: I next lowered
the temperature by shutting the damper, and opening the furnace door;
a singing from the aperture was soon observable, and when a coal was
held before it, rapid combustion ensued; nothing, however, was yet
visible: but as the temperature decreased, the steam became more and
more visible, the noise at the same increasing, until finally the
roar was tremendous, and might have been heard the distance of half
a mile. This was conclusive. I should mention that, at the aperture,
the iron was red-hot.” “The hole was one _quarter of an inch_ in
diameter.”
“The experiment affords some data towards answering the question,
at what distance from the heated metal the water remained, when
under the pressure of thirty atmospheres; we may safely aver that it
exceeded one-eighth of an inch.”—_Silliman’s Journal_, xiii. 46.
2. _On the Use of feeble Electric Currents, for effecting the
Combination of numerous Bodies, by_ M. Becquerel.—A highly
interesting memoir on this subject is inserted in the thirty-fifth
volume of the _Annales de Chimie_, the intention of M. Becquerel
being to show that electro-chemical powers may be used not only for
the decomposition and analysis of bodies, but also for the production
of new compounds.
The facts described in the paper are commenced by one intended to
illustrate future reasoning, by shewing what takes place when a very
feeble electric current traverses a metallic circuit, interrupted in
one part by a neutral solution, into which the two extremities of
the wires forming the circuit are immersed. Two small copper wires
were connected together by loops, and the two free ends joined to the
ends of a galvanometer wire; the circuit was then cut in one place,
and the extremities immersed in a solution of chloride of sodium.
Then, if one of the loops be raised to a red heat by a spirit lamp,
an electric current is produced, the heated loop furnishing negative
electricity. Now if the ends plunged in the saline solution are
terminated by platina or gold wires, _no current_ of electricity is
observed; with silver terminations, the current is very feeble; but
with wires of zinc, lead, iron or tin, the current is very energetic.
These remarkable effects, highly important in the phenomena hereafter
to be considered, are no way connected with the conductibility of
the metals; for lead and zinc, which are the worst conductors, are
those which, with the copper, produce the most powerful effects. The
current ceases altogether as soon as the lamp is removed.
As the zinc, copper, lead, and iron, belong to the class of oxidable
metals, M. Becquerel concludes, from this experiment, that [p463]
when very feeble electricities are generated in any point of a
metallic circuit, interrupted by a saline solution, _a current of
electricity is formed or not, according as the two similar metallic
terminations, which dip into the solution, belong to an oxidable or
non-oxidable metal_. If the saline solution be replaced by an acid,
_then_ a current will be obtained, though platina wires be used;
because that kind of fluid does not interrupt the current.
With respect to the production of new compounds by electro-chemical
powers, very much depends upon the strength of the power employed,
and M. Becquerel only pretends, as yet, to indicate a new field of
research, and not to point out the precise paths to be pursued.
Two methods may be adopted. As an illustration, let a tube, from
4 to 8 hundredths of an inch in diameter, be bent into the form
of the letter U, and place a plug of amianthus at the bend, to
prevent the mixture of the fluids in the limbs: into one leg put
a mixture of deutoxide of copper and solution of the sulphate of
copper, the former will fall to the bottom; into the other put a
saturated solution of common salt, and also an excess of the dry
substance, then communicate the two fluids by a plate of copper.
Very shortly the end plunged in the sulphate will be covered with
metallic copper, and the acid set free will act upon the oxide of
copper below and form more sulphate, so that a set of decompositions
and recompositions will occur, and ultimately comparatively large
crystals of copper will be obtained.
In the other branch of the tube, a portion of the salt will be
decomposed, the muriatic acid will act upon the copper, which is
oxidised in consequence of its positive state, and will probably
produce an oxychloride, which will combine with the chloride of
sodium, and then octoedral crystals will be formed on the plate of
copper. The effects are produced either with or without access to air.
When the crystals are well dried and inclosed in a tube hermetically
sealed, they suffer no change; but they are decomposed by water into
chloride of sodium and submuriate of copper.
If the voltaic experiment be continued for one or two months, the
crystals, from being colourless and limpid, become violet, and
ultimately acquire an emerald green hue, still remaining transparent.
If the chloride of sodium side be tested, it will be found that soda
is evolved during the experiment. A piece of copper simply immersed
in a solution of common salt, produces nothing more than a submuriate
of copper, which precipitates.
_With silver_.—If a similar tube to that described have both limbs
filled with a solution of salt, a platina wire introduced into one
limb, a silver wire into the other, the extremities of the wire
connected so as to form a voltaic circuit, and the whole left for
some months, in about fifteen days crystals will be observed on the
silver wire; these will gradually increase and assume a rhomboidal
form. They have not yet been particularly examined, but [p464] are
known to be unchanged by water: during a long experiment they change
colour, becoming, first, violet, then blue.
Experiments similar to that with the copper, when repeated with the
same solutions, &c., but the substitution of plates of lead and tin
for the copper plates, produced crystalline double chlorides of these
metals and sodium.
Muriate of ammonia being substituted for common salt in these
experiments, another series of double compounds was obtained with
copper, silver, lead, and zinc.
A double chloride of barium and lead was formed slowly in a similar
way.
When a solution of the iodide of potassium or sodium was used instead
of the solution of salt, then double iodides were obtained: thus
with lead rather a rapid formation of silky crystals occurred upon
the lead, which, when examined by water, were decomposed, producing
iodide of lead and solution of iodide of potash or soda. A tube
two or three times the diameter of the former may be used for the
experiment.
The second method of producing new combinations by weak
electro-chemical powers, depends upon the electro-motive action,
which is caused whenever a metal touches the oxides, or an oxide
of another metal. If an oxide of a metal, a plate of metal, and a
liquid be put into a tube closed at one extremity, there will be an
electro-motive action of the metal with the oxide, and of the liquid
with both these bodies; and the chemical effect will be according to
the resultant of these three forces, which can only be ascertained by
experiments.
As an illustration of the effects thus produced, three tubes, from
eight to twelve hundredths of an inch in diameter, were prepared,
a little protoxide of lead being put into one, deutoxide into the
second, and peroxide into the third; solution of muriate of ammonia
and a plate of lead were then added to each tube. After a time, lead
was precipitated in the first tube, very slight chemical changes took
place in the second, but a large quantity of double chloride of lead
and ammonia crystallized upon the lead in the third, in the form of
needles. Thus very different effects were produced, according to the
state of oxidation.
Solution of salt gave similar results with the oxides of lead and
lead.
The oxides of copper, with solutions of alkaline muriates, gave
curious results. With muriate of ammonia, crystals were produced of
considerable size, and different to those obtained by the former
process. In this experiment, the black and anhydrous deutoxide of
copper gradually acquired a blue colour, as if a hydrate were formed
under the influence of the feeble electric current formed by the
arrangement.
Copper, its deutoxide, and solution of corrosive sublimate, produced
a double chloride, crystallizing in plates, and possessing a metallic
lustre. [p465]
3. _Crystallization of Metallic Oxides_.—If a solution of nitrate of
copper, mingled with very fine charcoal powder, or even deutoxide
of copper, be put into a similar tube to that described in the last
article, then a plate of copper be introduced and the vessel closed
up, in about fifteen days small red transparent octoedral crystals
of protoxide of copper will be formed on the plate of metal. Other
metals have been subjected to similar experiments, but probably have
not yet remained long enough under action.—_Ann. de Chimie_, xxxv.
113.
4. _On Bromine, by_ M. A. de la Rive.—M. de la Rive has remarked
a curious fact respecting the conducting power of fluids for
electricity in the habitudes of bromine and water. He found, in the
first place, as M. Balard had stated, that pure dry bromine did not
conduct the electricity of a voltaic battery, consisting of sixty
pairs of plates very strongly charged, a delicate galvanometer being
the test: a similar experiment was then made with pure water, the
water being contained in a glass capsule, and communicated with the
battery and galvanometer by platina wires[129], and the deviation
of the needle was scarcely sensible. Some other experiments induced
M. de la Rive to believe, that water perfectly distilled and put
into vessels made of substances absolutely unacted upon, would not
conduct any portion of electricity: the purer the water, and the
more unchangeable the substance of the vessel, the feebler does the
conducting power become, until at last it is insensible.
A few drops of bromine were then added to the water, which soon
acquired a yellow colour, by dissolving a small portion of
the substance; being now included in the voltaic circuit, the
galvanometer needle was deviated 70°, and an abundant disengagement
of gas took place from the platina wires. These were oxygen and
hydrogen, in the usual proportion, proving that the water only had
been decomposed.
From these experiments it results, that a body which does not at all
conduct voltaic electricity, or at least but very badly, namely,
_pure water_, may be rendered a very good conductor, by its mixture
with a few drops of perfectly _non-conducting_ substance, namely,
_bromine_. M. de la Rive has found the same fact to occur with
iodine, and iodine and water; and his father had observed, in a
course of experiments made a long time ago on the conducting power of
fluids, that diluted sulphuric acid is a better conductor than very
much concentrated acid: may not anhydrous sulphuric acid then be a
non-conductor like bromine, &c.?—_Annales de Chimie_, xxxv. 161.
FOOTNOTE:
[129] See, on this point, the statement by M. Becquerel, p. 462,
relative to the use of platina wires, when forming a communicating
medium with fluids.
5. _Elementary Nature of Bromine_.—Iodine colours a solution of
starch blue, bromine renders a similar solution orange colour. M.
A. de la Rive added a few drops of bromine to a solution of starch
[p466] coloured blue by iodine, and obtained a compound which gave
two distinct colours with starch, one brown, the other yellow; the
difference of colour corresponding with the two bromides of iodine
described by M. Balard. These compounds of iodine and bromine,
dissolved in a solution of starch, were subjected to the voltaic
pile: immediately the yellow solution became blue about the negative
pile, and orange about the positive pile, indicating the separation
and places of the iodine and bromine. Thus the smallest quantity of
iodine may be discovered in bromine; but when the experiment was
resorted to, to prove whether the idea thrown out, that bromine was a
compound of chlorine and iodine, was founded in fact or not, it gave
no such indication, and a solution of bromine in starch electrified
for a long time together, gave no appearance of iodine. Hence M. de
la Rive concludes, that bromine contains no iodine, but is an element
analogous to iodine and chlorine.
When bromine and iodine are combined, the former passes to the
positive pole, and is consequently more negative than the latter;
which accords with the observation of M. Balard, that it should
occupy a place between chlorine and iodine.
According to the _Bulletin Universelle_, when the letter to M. Arago,
containing an account of the facts above referred to, was read to
the Academy of Sciences, that body decided that the assertion of M.
Dumas that bromine was a compound of chlorine and iodine should be
considered as retracted, and that it should be so entered, upon the
procès-verbal of the sitting.—A. viii. 209.
6. _Quantity of Bromine in Sea-Water_.—One hundred pounds of
sea-water, taken up at Trieste, treated by chlorine, ether, &c.,
according to M. Balard’s process, produced five grains of bromide
of sodium, or 3.278 grains of bromine. It would appear that, in the
sea-water of Trieste, the bromine is unaccompanied by any iodine, and
the same is the case, according to M. Hermbstadt, with the waters of
the Dead Sea. In the water of the Mediterranean, on the contrary,
iodine always appears with the bromine.
7. _Sale of Bromine_.—The discoverer of bromine, M. Balard, has
been enabled, by his improvements, to prepare that peculiar body
in quantities sufficient to permit its sale. It may be obtained
at his shop, Rue Argenterie à Montpellier, or at M. Quesneville’s
manufactory of chemical substances at Paris. The price is four francs
the gros (about 60 grains), fourteen francs the half ounce, and
twenty-three francs the ounce.
8. _Preparation of Iodous Acid_.—M. Pleischl says that, in preparing
this acid, three parts of chlorate of potash with one of iodine are
to be used, and not equal parts according to M. Sementini; and also
that it is indispensable to cool the receiver considerably during the
whole operation. [p467]
9. _On a peculiar Nitric Acid, and Sulphate of Potash, by_ Mr.
Phillips.—For the purpose of preparing nitric acid of the greatest
strength, Mr. Phillips mixed 70 parts of nitre with 70 parts of oil
of vitriol, S. G. 1.8442 at 60°, and distilled for eight hours. The
nitric acid obtained was reddish yellow, weighed 46.13 parts, was of
S. G. 1.5033, and by an experiment on carbonate of lime, was found
equivalent to 34.24 of that substance; the latter fact indicates
that 36.98 of real acid was present, and the liquid acid therefore
consisted of
Real nitric acid 36.98 or 80.16
Water 9.15 19.84
----- ------
46.13 100.00
Supposing this acid to be a definite compound of two atoms of acid,
108, and three of water 27, it would consist of
Real acid 36.90 or 80
Water 9.23 20
----- ---
46.13 100