MET 
MESSERSCHIMIDIA, in botany, so, 
named from Daniel Gottlieb Messerschmid 
a genus of the Pentandria Monogynia 
class and order. Natural order of Asperi- 
foli®. Borragineae, Jussieu. Essential cha- 
racter : corolla funnel form, with a naked 
throat; berry suberous, bipartile, each two 
seeded. There are two species, viz. M. 
fructieosa, and M. arguzia. 
MESUA, in botany, so called from John 
Mesne, a physician, a genus of the Mona- 
delphia Polyandria class and order. Na- 
tural order of Guttiferae, Jussieu. Essen- 
tial character: calyx simple, four leaved; 
corolla four petalled ; pistil one ; nut four 
cornered, one seeded. There is but one 
species, viz. M. ferrea, a native of the East 
Indies : it is much cultivated in Malabar, 
for the beauty of the flowers ; it bears fruit 
from the nut at six years old, and continues 
frequently bearing during three centuries. 
It is a very large tree, spreading like the 
lime ; the flowers resemble our sweetbriar 
roses, having only four white petals ; the 
fruit when ripe has a rind like that of the 
chesnut,with three or four kernels within 
of the substance, shape, and taste of ches- 
nuts. 
METACARPUS, in anatomy,- that part 
of the hand between the wrist and the fin- 
gers. 
METALS, according to strict definition, 
are inflammable bodies, being all capable of 
combining with oxygen, and many of them, 
during this combination, exhibit the pheno- 
mena of combustion. Formerly only seven 
metals were known, but modern discove- 
ries have added to the nuntber about twenty 
others, which are distinguished by their 
great specific gravity, considerable tenacity 
and hardness, opacity, and property of re- 
flecting the greater part of the light which 
falls on their surface, giving rise to what is 
denominated the metallic lustre or bril- 
liancy. See Lustre. To these have been 
added two others by Mr. Davy, who has 
dbcovered the method of decomposing 
potash and soda, and producing thereti ora 
tlie new metals called by that professor Po- 
tassium and Sodaium. See Potassium and 
and Sodaium, under which terms a more par- 
ticular account of these metals will be given. 
Of the others the principal characteristic is 
their superior specific gravity. In this they 
exceed all other bodies, the lightest being 
about six times heavier than water, the com- 
mon standard, while the spec fic gravity of 
the heaviest substance with which we are ac- 
MET 
quainted, that is not metal, is less than five 
times heavier than water. Opacity is 
another leading property of metals ; even 
when beat to the greatest possible thin- 
ness, they transmit scarcely any light : from 
the union of the two qualities, density and 
opacity, arises that of lustre. By their 
opacity and the denseness of their texture, 
they reflect the greater part of the light that 
falls on their surface. From their density 
they are susceptible of a fine polish, by 
which their lustre is increased. Colour is 
not a characteristic property of metals, but 
it serves to distinguish them from each 
other. Their colours are generally shades 
of white, grey, or yellow. Tenacity distin- 
guishes a number of the metals, and is not 
possessed in any great degree by other bo- 
dies: hence arises their Malleability and 
Ductility, w'hich see. Some of the metals 
are neither malleable nor ductile. Metals 
are less hard than the diamond and many 
fossils, and their elasticity follows the same 
order as their hardness. Both these quali- 
ties are greater in combinations of the me- 
tals than in the individual metals, and both 
may be increased by raising the metal to a 
high temperature, and then suddenly cooling 
it. Metals are the best conductors of calo- 
ric ; their expansibilities are various, and 
are probably nearly in the order of their fu- 
sibilities. Mercury melts at so low a tempe- 
rature, that it can be obtained in the solid 
state only at a very low temperature ; 
others, as platina, can scarcely be melted by 
the most intense heat^ which we can ex- 
cite. In congealing, some of the metals 
expand considerably, especially iron, bis- 
muth, and antimony ; the others contract, 
some of them to a great extent, the contrac- 
tion of mercury being equal to the j^rd of the 
whole volume. Metals may be volatilized; 
at the degree of 600 quicksilver may be 
volatilized ; and zinc and arsenic at a tempe- 
rature not very remote from this ; many 
others may be dissipated in the focus of a 
large burning mirror, or by a pow-erful gal- 
vanic battery. Metals are the best con- 
ductors of electricity. 
Metals are susceptible of combination ; 
they have an affinity to oxygen, hydrogen, 
carbon, sulphur, phosphorus, and to each 
other, and when combined with oxygen, to 
alt the acids, to the alkalies, and to the 
earths. The metals, independently of po- 
tassium and sodaium, may be thus enume- 
rated and ai'ranged. 
