$66. 
electrical polarity; the one end is posi- 
tive, and the other negative. If the 
tounnaline (a crystal from Ceylon) be 
heated, one end of the crystal: becomes 
positively electrified, and the other nega- 
tively. If the crystal be broken into a 
number of parts,’ cach part has the same 
form as the large crystal; and’ each of 
these emall erystals has its attracting and 
. wepelling electrical’ poles. Here, some 
connection between magnetism, electri- 
eity, and crystallization, may be traced+ 
Crystallization is the effect of chemical 
affnity, by which the particles arrange 
themselves in certain forms, according to 
the shape of the primary molecule, and, 
probably, by some law, connected with 
thie polarity of each'particle. Light ap- 
pears also to- be refracted according to 
some law connected with its own polarity 
and that of the refracting medium. The 
double refraction of light, in passing: 
through Feeland crystal, always takes 
place on the plane, in @ line with the 
axis of crystal; and’ if the orystal be 
broken into smaller ones, each of these 
has the same property of double refrac- 
tion in the direction of its axis. When 
the light falls upon the crystal with a 
certain angle of incidence, only one re- 
fraction takes place; in another angle, 
there are four refractions, or images, of 
the object seen. Dr, Davy was inclined 
to believe, that each particle of light had 
its polar axis, and attracting and repel- 
ling poles, and that its refractions and: 
reflections were dependent on this pola- 
nity. 
mention, that what he advanced’on this 
intricate subject, he stated to be, in x 
considerable degree, hypothetical, and 
entitled to no more regard than what it 
miglit derive from future experiments. 
We have been more particular in stating 
these conjectures, as they appear to offer 
the most plausible solution. of what are 
called, the fits of easy transmition and: 
reflection of light, hitherto given—The 
positive and negative electricities natural 
to different bodies, makes their decom- 
position by electrical agency practicable, 
in cases where they could be decomposed 
by no other known methods. Llence, 
the voltaic pile, or battery,, becomes 
the most powerful instrument in the 
hands-of the chemist. The Freneh phi- 
Josophers have lately published an ac- 
count of some experiments made to de- 
termine the powers of different piles; 
and have asserted, that the energy of 
each pile is in the proportion of the cube 
soot of the nunrber of plates. In order 
Literary and Philosophical nielligence. 
kt is only justice to Dr. Davy to: 
et a 
[4 pri¥ 3, 
to produce a double effect, they state, 
that the number of plates must be in- 
creased eight times. Dr, Davy, on the 
contrary, found the energy of the battery: 
to increase in a much greater ratio. with: 
the number of plates. Ten plates of 
metal, 1% inches and. a half io lengthy. 
and 4and a half in breadth, ignited am 
iron wire 2 inehes in length. Twente. 
plates ignited Sinches, and thirty plates: 
ignited 12 inzhes of the same wire. The 
error in the catculations of the Frenchy. 
is attributed to their making use of piles- 
instead of troughs, by which means a 
considerable part of the effect is lost. 
The battery at the Royal Institution con= ! 
sists of troughs) made of Wedgwood’s 
ware, divided into separate cells, filled 
with water, containing a smail portions 
of nitricacidy The plates are suspended) 
from a piece of wood,. the Jength-of the 
trough, by which means they can all be: 
immerged in the cells, or taken out, to- 
gether. When a. very powerful battery: 
1s wanted, a number of these troughs are- 
connected. All the metals are fused by 
it, but more readily in vacuo than in the: 
air. Platina, which is the mostinfusible 
metal by other means, melts, by the 
operation of the voltaic body, sooner 
than zinc. During the fusion of platina 
wire in vacuo, anumber of vivid sparks- 
were given out, which Dr. Davy ima- 
gined’ snap from the disengagement: 
of hydrogen, which forms a constituent 
part of carbon and: the metals.—In re- 
gard to meteoric stones, he observesy,- 
that hydrogen gas, or inflammable air, 
will dissolve some of the metals, and 
form, with them, an invisible metallie 
gag. When this gas is exploded, the 
metals are deposited in a metallic form. 
on the sides of the vessel in which the: 
experiment is made. Arsenic, tellurium,, 
and sodium, were exhibited,. in a gaseous: 
state, combined with hydrogen. When: 
the hydrogen was. inflamed, by a mix 
ture of oxymuriatic gas, the metals were: 
deposited’ in a solid form, coating the 
sides of the vessels, Dr. Davy observed, 
that the stones which had fallen. fram the- 
atmosphere were all metallic, and might, 
perhaps,. be furmed by the explosion of a 
large quantity of inflammable air, in 
which: the metals. had been. dissolved. 
He was, however, inclined to trace their 
origin to another cause, and to consider 
them as the ruins of some planetary 
body; or, perhaps, they might be sinall 
satellites, moving round some. of the 
planets, which, coming near the orbit of 
the earth, were attracted to it, We 
know. 
oO" 
