ISO 
yellowish colour; it occurs massive, and 
crystallized. Specific gravity 2.5 nearly. 
Before the blow pipe it froths, and melts 
into an opaque head. It is supposed to 
consist of 
Silica 
... 24.5 
Potash 
Water 
Loss 
99.6 
100 
ICONOCLASTS, in church history, an 
appellation given to those persons who, in 
the eighth century, opposed image-worship, 
and is still given by the Church of Rome 
to all Christians who reject the use of images 
in religious matters. 
ICOSAHEDRON, in geometry, a re- 
gular solid, consisting of twenty triangular 
pyramids, whose vertexes meet in the cen- 
tre of a sphere, supposed to circumscribe 
it ; and, therefore, have their height and 
bases equal ; wherefore the solidity of one 
of those pyramids multiplied by twenty, 
the number of bases, gives the solid con- 
tent of the icosahedron. See Body. 
ICOSANDRIA, in botany, the name of 
the twelfth class in the Linnaean system, 
consisting of plants with hermaphrodite 
flowers, furnished with twenty or more sta- 
mina, that are inserted into the inner side 
of the calyx, or petals, or both. By this 
last circumstance, and not by the number 
of stamina, is this class distinguished from 
the class polyandria, in which the number 
of stamina is frequently the same with that 
of the plants of the class icosandria, but 
they are inserted, not into the calyx or pe- 
tals, but into the receptacle of the flower. 
The icosandria furnishes the pulpy fruits 
that are most esteemed, such as apples, 
plumbs, peaches, cherries, &c. whereas the 
polyandria are mostly poisonous, as the aco- 
nite, columbine, larkspur, hellebore, and 
others. The species of the icosandria have 
a hollow flower cup composed of one leaf 
to the inner side of which the petals are 
fastened by their claws. In this class there 
are five orders, founded upon the number 
of the styles or female organs. The myr- 
tle, almond, and plumb have a single female 
organ ; the wild service, two ; the service 
and sesuvium, three; medlar and apple, &c. 
five ; rose, raspberry, strawberry, &c. an 
indefinite number. 
IDE 
IDENTITY, denotes that by which a 
thing is itself, and not any thing else 5 in 
which sense, identity differs from simili- 
tude as well as diversity. The idea of iden- 
tity we owe to that power which the mind 
has of comparing the very being and ex- 
istence of things, whereby considering any 
thing as existing at any certain time and 
place, and comparing it with itself as ex- 
isting at any other time and place, we ac- 
cordingly pronounce it the same, or differ- 
ent. Thus, when we see a man at any time 
and place, and compare him with himself 
when we see him again at any other time 
or place, we pronounce him to be the same 
we saw before. 
To understand identity aright, we ought 1 
to consider the essence and existence, and 
the ideas these words stand for ; it being 
one thing to be the same substance ; another 
the same man ; and a third, the same per- 
son. For, suppose an atom existing at a 
determined time and place, it is the same 
with itself, and will continue so to be at any 
other instant as long as its existence conti- 
nues ; and the same may be said of two or 
any number of atoms, whilst they continue 
together ; the mass will be the same ; but 
if one atom be taken away, it is not the 
same mass. In animated beings it is other- 
wise, for the identity does not depend on 
the cohesion of its constituent particles, any- 
how united in one mass; but on such a 
disposition and organization of parts, as is 
fit to receive and distribute life and nou- 
rishment to the whole frame. Man, there- 
fore, who hath such an organization of parts 
partaking of one common life, continues 
to be the same man, though that life be 
communicated to new succeeding particles 
of matter vitally united to the same organ- 
ized body; and in this consists the identity 
of man, considered as an animal only. But 
personal identity, or the sameness of an in- 
telligent being, consists in a continued con- 
sciousness of its being a thinking being, en- 
dowed with reason and reflection, capable 
of pain or pleasure, happiness or misery, 
that considers itself the same thing in dif- 
ferent times and places. By this conscious- 
ness every one is to himself, what he calls 
self, without considering, whether that self 
be continued in the same or divers sub- 
stances ; and so far as this consciousness ex- 
tends backward to any past action, or 
thought, so far extends the identity of that 
person, and makes it the object of reward - 
and punishment. Hence it follows, that if 
the consciousness went with the hand, or 
