ITC 
XX — dx-\-\dd=z — 5 + 
\/ + 
Thus if one side of the square be 10 ; and 
one side of an oblong be 19, and the other 
1 ; tlien will the ambits of that square and 
oblong be equal, viz. each 40, and yet the 
area of the square will be 100, and of the 
oblong but 19. 
ISOPYRUM, in botany, a genus of the 
Polyandria Polygynia class and order. Na- 
tural order of Multisilique. Ranunculacese, 
Jussieu. Essential character: calyx none; 
petals five ; nectary trifid, tubular ; cap- 
sule recurved, many-seeded. There are 
three species. 
ISOSCELES triangle, in geometry, one 
that has two equal sides. See Geomethy. 
ISSUE, in law, has many significations, 
sometimes being used for the children be- 
gotten between a man and his wife; some- 
times for profit growing from amerce- 
ments or fines ; and sometimes for profits of 
lands or tenements ; sometimes for that 
point of matter depending in a suit, when, 
in the course of pleading, the parties in the 
case affirm a thing on one side, and deny it 
on the other, they ai^ then said to be at 
issue ; all their debates being at last con- 
tracted into a single point, which may be 
determined either in favour of the plain- 
tiff or defendant. 
Issues, in surgery, are little ulcers made 
designedly by the surgeon in various parts 
of the body, and kept open by the patient 
for the preservation or recovery of his 
health. 
ITCH, a cutaneous disease, supposed to 
be caused by an insect, a species of the 
genus Acarus, viz. A. scabiei, which, when 
viewed by a good microscope, is white with 
reddish legs ; the four hind ones having a 
long bristle. It is found in the small pellu- 
cid vesicles with which the hands and 
joints of persons infected with the itch are 
covered. It appears to be not only the 
cause of the disorder, but the reason why it 
is so highly infectious. 
ITCHING, an uneasy sensation, which 
occasions a desire of scratching the place 
affected. It is frequently a troublesome 
sensation, but more nearly allied to plea- 
sure than pain. As pain is supposed to 
proceed from too great an irritation, so 
does itching proceed from a slight one. 
Certain species of itching excites people to 
many necessary actions, as the excretion of 
the feces and uruie ; coughing, sneezing, &c. 
ITT 
ITEA, in botany, a genus of the Pen- 
tandria Monogynia class and order. Natu- 
ral order of Rhododendra, .Iiissieu. Essen- 
tial character: capsule two- celled, two- 
valved, many-seeded ; stigma emarginatc. 
There are two species, viz. I. virginica. 
Virginian itea ; and I. cyrilla, entire-leaved 
itea. These are both shrubs. Linnaeus re- 
marks, that the itea virginica has the ap- 
pearance of the Padus ; that the leaves are 
petioled and the flowers in terminating 
racemes. The stigma is headed in this spe- 
cies, wiiereas in the other it is bifid or 
double; the former is a native of North 
America ; the latter of Carolina and Ja- 
maica. 
ITl’RIA. This earth was discovered by 
Gadolin, a Swedish chemist, in a fossil, found 
at Ytterby, in Sweden, which has since re- 
ceived the name of gadolinite, and in which 
it is combined with silex and lime. The 
discovery was confirmed by Ekeberg, Klap- 
roth, and Vauquelin ; and the same earth 
has been discoyered in some other fossils 
particularly combined with lantaliuni. In 
several of its properties ittria resembles 
glucine, particularly in forming salts of a 
sweet taste, and in being soluble in carbo- 
nate of ammonia ; but it differs entirely in 
others. 
The process followed by Vauquelin to 
obtain this earth from the gadolinite was to 
dissolve it, with the assistance of heat, in 
diluted nitric acid, pouring off the solution 
from the undissolved silex. The liquor is 
then evaporated to dryness by which any 
remaining silex and any oxide of iron is 
separated from combination with the a- 
cid. By redissolving the residuum in wa- 
ter, the compound of nitric acid and ittria 
is obtained : if there are any traces of 
iron, the liquor is either again evaporated 
to dryness or a tittle ammonia is added; 
and after tiie separation of the oxide of 
iron by yellow flakes, the solution is de- 
composed by ammonia, which precipitates 
the new earth. (Philosophical Magazine, 
vol. viii. p. 369.) The process employed 
by Klaproth is similar ; nitro-miiriatic acid 
being employed; the iron being remov- 
ed by the action of succinate of soda; 
and the ittria being jirocipitated by carbo- 
nate of soda. (Analytical Essays, vol. ii.- 
p. 47.) 
Ittria is obtained in the form of a white 
powder, and is heavier than any other 
earth ; its specific gravity according to 
Ekeberg being 4.842. It is not fusible 
alone, but with borax it forms a white glass. 
