Abbildungen der Seite

when the copper of the original is of a good quality. As soon as the galvanic plate has acquired the requisite thickness, and the parts grown over the edges of the original are filed away, it springs loose of itself, without any further trouble. It hardly need be mentioned, that a casting of gypsum would answer all the purposes of copper plate, provided it were nicely managed, and taken from an original engraving that was not under-cut.

(To be continued.)

On Voltaico-Electric Quantity and Intensity. By Dr. Buff. (Ann.

der Pharm., t. 32, p. 1.*)

The author has had in view the study of that species of mysterious property which Faraday conceives to be found in voltaic electricity, by virtue of which it is more easily transmitted ; a property which he has named intensity, and which he distinguishes from quantity. He has found that this property is, as I have already indicated, only an effect of conductibility, by virtue of which the neutralization of two electricities accumulated at the poles of the pile is more or less easy.

The experiments of Dr. Buff are not all new, but they are interesting, as they confirm those which have already been made on the same subject by other philosophers.

He arrived at the conclusion, by varying the number of pairs in a pile, that if the circuit is closed by an imperfect conductor, the facility which this possesses of transmitting the quantity of electricity which can be developed by the battery is universal in proportion as the number of pairs is augmented.

The effects of tension observed by Dr. Buff are more numerous and more remarkable. He has at first studied them on a pile, the poles of which were insulated. The centre pair gave the same tension as it possessed when alone; two pairs, apart from the middle of the pile, gave a stronger tension; three, a still stronger ; and so on to the poles, where the electricity attains its maximum. The author appreciated the electrical state of each pair in diverse manners, and in particular by means of a copper wire soldered to zinc, which he put in contact with the inferior plate of the condensor, whilst he touched the superior one with the finger.

By making the poles communicate with each other by distilled water, the same distribution of free electricity in the pile has been found, only it was a little more feeble. With acidulated water placed between the poles, and which was decomposed, the electricity of tension was still found in those pairs nearest to the poles. But no portion of it could be found when the poles had been metallically united.

*Archives De L'Electricitie, No. 1.

The same effects have been obtained by charging the pile with diluted sulphuric acid, in place of ordinary water. By reuniting the poles by distilled water, the tension was still feebler, and no decomposition took place in any part; but when reunited by acidulated water, decomposition took place in all parts, in the troughs of the pile, as well as in those into which the poles were inserted. The tension has in all cases been stronger at the poles.

The author remarks the analogy which exists between these effects and those of an ordinary electric battery, charged with electricity from a machine ; and he thence concludes that the greatest tension, or the static intensity of the pile, only proceeds from the resistances which the circulation of the electricity meets with. We conceive, then, that it is at its maximum at the poles, and that, without being obliged to attribute to the current a mysterious property, there exists for the two electricities, accumulated at the two poles, a tendency to neutralization, more or less strong, and consequently a greater facility for the current which results from this neutralization to traverse the imperfect conductors.

On an Advantageous Manner of Constructing Grove's Pile. By

C. A. Gruil. (Ann. der Physik, tome li. p. 381.)* The author at first constructed this pile by placing a cylindric ring of platinum, in a porous earthen tube, closed at its lower extremity, and filled with nitric acid. The porous tube was introduced into a cylindrical jug, filled with diluted sulphuric acid, in which was also inserted a cylinder of amalgamated zinc, which enveloped the tube without touching it. This piece of apparatus, which is almost similar to a calorimeter, gave powerful results, but it presented this inconvenience: the thin layer of nitric acid, comprised between the surface of the cylindric ring of platinum and the interior partition of the porous tube, became rapidly heated, entered into a state of ebullition, and emitted nitrous vapours.

The author then substituted, for the cylindric ring of platinum, two plates of the same metal, cutting each other at right angles, following the axis of the tube, and forming a cross.

He has, even at a later period, added a third plate, in such a manner that the three plates crossed each other at the axis, by making angles of 60° with each other. They were thus disposed around the axis, like the leaves of an open book round the back of the book.

After this disposition, all the nitric acid being in the circuit was much less heated. This pair would act during several hours without any disengagement of gas or decrease of the force of the current, when even the nitric acid had taken a deep green colour.

Archives De L' Electricitie, No. 1.

A Register of the Electric State of the Atmosphere, in relation to its

Meteorological Phenomena, for the Month of June, 1841. By W. H.

JUNE, 1841.

Time in hours and minutes.

| Day of month.

[blocks in formation]

| Thermometer.
Barometer in
inches and

[blocks in formation]



6,15 p.m.

74 29.90 mere Mountainous mass- positive An occasional, low current,
zephyr, es of cumulus cloud.

causing slight divergence
W. by S.

until 2 P.M.
176 29.95 zephyrs, Blue sky, with nu- positive Moderate divergence until
W. by S. merous beautiful

modifications of

174 29.30 zephyrs, Blue sky, with here positive Divergence uniform but trivial.

N.V. and there cirrose

66 29.90 moderate Very fair, with cu- positive Steady repulsion of gold leaves.

breeze. mulus cloud.
N. by W.
S. by E.

positive Remarkably steady divergence

until the approach of sunset.
66 29.90 breezes, Thin haze, sun positive Steady divergence, moderate.
N. by W. breaking through

at times.
29.70 direct N. Successive gentle negative Pendulums in state of constant

divergence, and frequently

60 29.60 breeze N. Cloudy,-rain drops positive Strong divergence, with an oc-
at times.

casional intermission of a
few minutes, when the gold
leaves lose their repulsive

condition suddenly.
58 29.50 breeze N. Cumulo-stratus. positive Sudden divergence on the ap-

proach of a ragged cumulus. 11 a.m.

Hasty, showers of negative Streams of moderate sparks
small rain,

from terminus. 11,9 a.m.

positive Increased energy of electric

current for the space of an
hour, followed by a laboured
and heaving motion of the

gold leaves. 1, 20 p.m.

Hail shower. positive Torrent of brilliant sparks.
moderate Frequent hasty variable Discharge of sparks as hitherto,
gale N.

during the showers, Dega-
by W.

tive; with a strong positive

current in the intervals.
60 29•60 very little Cloudy dark sky. positive Trifling divergence in two in-
at times,

stances only, during a few
N. by W.

62 29.50 light Uniformly cloudy. neutral Scarlatina, in a mild form, is
breeze at

somewhat prevalent.
times, N.


3 p.m.

[blocks in formation]




60 29.56


Hazy upwards, with neutral Cynanche tonsillaris, frequent slight, n. little fine rain at

among children and young by E. times.

persons 58 29.65 faint Thickly clouded. neutral



light Veil of cloud rapid-positive The electroscopes diverge breeze ly dispersing,

has sud blue sky, with
denly a here and there a
risen from modification of

N.E. cumulus.
62 29.50 zephyrs, Fine, with various positive Slight divergence at times,
S.E. clouds.

during morning only, — dis

tant lightning at eve.
62 29.70 breezes, Manifold dense neutral

variable clouds, at great
from W. altitudes.

to N.
62 29.75 light Blue sky, with mo. positive Free divergence until sunset.

breezes, difications of cir-
variable rus.
from S.E.
to S. by

63 29.65 breezes, Clear sky, and fea- neutral

S. by W. thery cirri.
has varied

positive Free and continuous electric to S. E.





2,30 p.m.


by E.

4 p.m.

6, 10 p.m. 6,25 p.m.

light Blue sky, with cir. positive Free divergence. breezes, rose fibres dis

E. by N. persed abroad. 2 p.m. 66 29.40 S. by W. The cirrose fibres All divergence has ceased.

have gradually re-
solved into cirro

Various modifica- neutral

tions of cumulus.
Thunder approach- negative Continuous discharge of sparks.

Storm-cloud passing positive Energy of electric current de-
rapidly over; - a

moderate shower.
Heavy rains before

Cumulo stratus and neutral

distant pimbus.


8 a.m.

Time in hours and minutes.

5 Day of month.

Wind, its
direction Weather and modifi-

and cations of clouds.

| Thermometer.
Barometer in
inches and

Geceral Remarks.


of at-

5 p.m.

6 p.m.

19 2 p.m. 66 29:32 light Thunder from negative Waves of electric fluid rush breezes, clouds distant

through the apparatus subW. about a mile.

sequent to each successive

lightning-flash. 12, 20 p.m.

Rain in abundance. positive Current of small sparks.
Frequent showers.

No further trace of elec. action. 20 164 29.50 strong at Densely clouded. neutral

times, W.S.W. decreased Continued gentle neutral Numerous cases of odontalgia.

rain. 21

66 29.60 sudden Occasional gentle neutral

squalls showers.

moderate Clear sky.

neutral Sensation of langour and mus

cular relaxation very general. 22 66 29.65

Clouds and thin neutral zephyrs haze beneath.

W.S.w 1,25 p.m. increased Hasty dispersion of positive Slight divergence of electroto smart clouds, except fine

scopes immediately on disbreeze, cirrose fibres, here

persion of clouds; increasing S.W. and there.

for one hour, becoming uni

form, and ceasing at sunset. 23 64 29.50

Blue sky and mo- neutral Odontalgia, rheumatism, and difications of cir

various neuralgic affections rus alternately.

abound. 24

Clear blue sky. neutral 2 p.m. 66 29.40

smart Few modifications positive Free divergence immediately breeze of cirrus cloud.

on rising of the breeze. has just sprung


by W.



up from

6 p.m.

S.E. byE.
has Clouds increased

The most delicate test-instruceased continued rain by

ments fail to detect any free night.

electricity. All the lastnamed diseases are increased: extreme langour of the animal

system prevails. 25

64 29.30 scarcely Continued gentle neutral

evident rain.

from S.E. 11,30 a.m.

breeze, Fair with flocculent neutral
S.W. cirri and cirro

cumulus. 26


Blue sky with cu- neutral
S.W. mulo fioccosus.

2,30 p.m. 67 29.45 slightly Nimbus flying has- negative Free divergence when a nimabated tily over.

bug reaches zenith of appa

ratus. evening

decreased Numerous modifica- positive Slight divergence steadily. to a smart tions of cirrus.


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