470 
by some of the liquor used in exciting the 
large battery, to which was added a 
small portion of fresh sulphuric acid, he 
readily decomposed potash and barytes :- 
in that state it produced the metallization 
of ammonia with great facility ; it ignited 
charcoal vividly; it caused great diver- 
gence in the leaves of an electrometer ; 
and it gave a vivid spark after being in 
action three hours. Hence it is inferred, 
that Mr. Davy’s theory is accurate, viz 
“that the intensity increases with the 
number of plates, but that the quantity 
of electricity increases with their size.” 
Thus the platina wire being a perfect 
conductor, and not hable to be oxydated, 
presents no obstacle to the free passage 
of the electricities through it; which, 
from the immense quantities given out 
from so large a surface, evolve, on their 
mutual annihilation, heat sufficient to 
raise the temperature of the platina to 
the point of fusion, With the iron wire 
the effect was different, on account of 
the low intensity of the electricity, (sufh- 
ciently proved by its not causing’ any 
divergence of the gold leaves of the elec- 
trometer) which being opposed in its 
passage by the thin coat of oxide formed, 
on the iron wire at the moment the cir- 
cuit is completed, a very small portion 
only of it is transmitted through the wire. 
To the same want of intensity is to be 
attributed the mability of the large bat- 
tery to decompose the barytes, and its 
weak action on imperfect conductors in 
general. ‘The small battery, on the con- 
trary, exerts great power on imperfect 
conductors, decomposing them readily; 
although its whole surface is more than 
thirty times less than that of the great 
battery: but in point of number ‘ef 
plates, it consists of nearly ten times as 
many as the large one. The long-con- 
tinued action of the small battery, shews 
the otility of having cells of a sufficient 
capacity to’ hold a iarge quantity of Ii- 
guor; and in jarge combinations, a certain 
distance between each pair of plates is 
absolutely necessary to prevent spon- 
taneous discharges whicn will otherwise 
ensue. Mr. Children also made expe- 
riments to ascertain whether there was 
any striking distance in tie Voltaic 
spark; and he found that with twelve 
bundred and fifiy plates, four square 
inches¢urface each, the striking distance 
was about 4th of an inch in length, 
and he assuines, that by increasing the 
number of the plates, the striking dis- 
tanee will also beinereased, 
Proceedings of Learned Societies. 
[June 1, 
“<The absolute effect,” he says, “ of a 
Voltaic apparatus, seems to be in the 
compound ratio of the number and size 
of the plates: the intensity of the elec- 
tricity being as the former, the quantity 
given out as the Jatter; consequeutly re- 
gard must be had in its construction to 
the purposes for which it is designed. 
For experiments on perfect conductors 
very large plates are.to be preferred, a 
small number of which will be suficient; 
but where the resistance of imperfect 
conductors Is to be overcome, the coms 
bination must be great, but the size of 
the plates may be small; but if quantity 
aid intensity be both required, then a 
large number of large plates will be 
hecessary. For general purposes, four 
inches square will be found to be the 
most convenient size.” 
Mr. Fverarp Homer, in examining the 
internal structure Of a Squallus maximus, 
met with a peculiarity in the interver- 
tebral substance of the spine, not hitherto 
noticed ; an account of this subsiance, as 
_ found in‘¥ish and guadrupeds, he has laid 
before the royal society. It is fluid of 
the consistence of liquid jelly, with a 
tendency to coagulation. In the squai. 
lus, the form of the cavity is nearly sphe- 
rical, capable of containing three pints 
of liquid. The fluid being incompres- 
sible, preserves a'proper interval between 
the vertebre to allow of the play of the 
lateral parts, which are ligamentous and 
elastic, and forms a ball round which the 
concave surfaces of the vertebre are 
moved, and readily adapts itself to every 
change which takes place in the form of 
the cavity. The elasticity of the liga- 
ments, by its constant action, renders 
the joint always firm, independently of 
any other support, and keeps the ends 
of the vertebre opposed to each other, 
so that the whole spine is preserved ina 
straight line, unless it is acted on by 
muscles or some other power. When a 
muscular force is applied to one side of 
the spine, it stretches the elastic ligament 
on the opposite side of the joint, and as" 
soon as that force ceases to act, the 
joint returns to the former state, which 
is one of the most beautiful instances in 
nature of elasticity being employed.as a 
substitute for muscular action. The ex- 
tent of the motion in each particular 
joint is undoubtedly small, but this is 
compensated by their number, and the 
elasticity of the vertebre themselves. 
Fish in general have their vertebra 
formed with similar concayities to ee 
e 
