MOL 
peduncles or feet : of these there are five 
genera, viz. 
Amphitrite Nereis 
Aplirodita Spio 
Nais 
G, mouth placed beneath and generally 
central. There are five genera, viz. 
Asterias Medusa 
Echinus Physsophora 
Lucernaria 
MOLOSSES, in commerce, the thick 
fluid matter remaining after the sugar is 
made, resembling syrup. See Sugar. 
MOLTING, the change of feathers, 
hairs, ,or horns, in birds and beasts. 
MOLUCCELLA in botany a genus, of 
the Didynamia Gymnospcrmia class and 
order. Natural order of Verticillata;. 
Labiatas, Jussieu. Essential character ; 
calyx, bell-shaped, widening, broader than 
the corolla, spiny. There are three spe- 
cies, of which M. spinosa, prickly Mo- 
lucca bauin, has an annual root, with pur- 
plish, smooth stems, four feet iu height, 
branching; leaves small, on short foot stalks 
acutely indented on their edges ; calyx, 
cut into eight segments, each terminated 
by an acute spine; flowers in whorls. It 
is a native of the Levant. 
MOLYBDATES, in chemistry, salts 
formed from the molybdic acid and the 
earths, alkalies, &c. They are mostly colour- 
less, and soluble in water ; they have a 
metallic taste. The prussiate of potash 
throws down from several of them a light 
brown coloured precipitate. 
MOLYBDENUM is a metal of a grey- 
ish white colour, in the form of brittle in- 
fusible grains. Formerly two substances 
were confounded together, which being ex- 
amined by the industrious and accurate 
Scheele ; he gave to the one the name of 
plumbago, which is composed of carbon 
and iron ; the other he called molybdenum. 
In colour it resembles lead, but in the 
analysis was obtained sulphur, and a whitish 
powder, which possesses the properties of 
an acid, This Bergman suspected to be 
a metallic oxide, which has since been de- 
monstrated to be the case. Hitherto this 
metal is only obtained in grains, the great- 
est heat has not been sufficient to melt it 
into a button; its specific gravity is 7.4. 
Wlien exposed to heat, in an open vessel, 
it gradually combines with oxygen, and is 
converted into a white oxide, which is vo- 
latilised in small brilliant needle form cry. 
MOM 
stals. This oxide having the properties of 
an-acid is called the molybdic acid. 
Molybdenum is capable of combining 
with four different proportions of oxygen, 
and of forming four oxides, the black, the 
blue, the green, and the yellow or white. 
To the green is given the name of molyb- 
dous acid. It combines readily with sul- 
phur, and in that state it is called molyb- 
dena, the sulphuret of molybdenum. This 
may be formed by distilling together one 
part of molybdic acid and five parts of 
sulphur. It will also combine with phos- 
phorus. Muriatic acid has but little effect 
on the metal; but it dissolves the oxide. 
Molybdenum will unite with many of the 
metals forming with them alloys. 
Molybdena, or sulphuret of molybdenum, 
occurs massive, disseminated, and rarely 
crystallized. Its colour is like that of fresh 
cut metallic lead. It occurs in granular 
distinct concretions ; it is opaque, stains the 
fingers, leaves shining traces when drawn 
over paper ; it is very soft and easily di- 
visible in the direction of its laminae. Spe- 
cific gravity 4.5 to 4.7. It is infusible be- 
fore the blow-pipe, but exhales a sulphure- 
ous odour ; at a very high heat, it melts, 
gives out white fumes and burns with a 
blue flame ; it consists of 
Molydic acid 45 
Sulphur 55 
100 
It is found in Norway, Sweden, Saxony, 
and in Mont-Blanc in Switzerland. 
MOLYBDIC 1 add. See above. Mo- 
MOLYBDOUS i lybdic acid combines 
with alkalies, earths, and several metallic 
oxides and forms Molybdates, which 
see. This acid, combined with potash, 
forms a colourless salt ; mixed with filings 
of tin and muriatic acid, it becomes blue, 
and precipitates flakes of the same colour, 
which disappear after some time. It is 
composed of 
Molybdenum 67 
Oxygen 33 
100 
MOMENT, in the doctrine of time, an 
instant, or the most minute and indivisible 
part of duration. Strictly speaking, how- 
ever, a moment ought not to be considered 
as any part of time, but only as the termi- 
nation or limit thereof. 
Moment, in the doctrine of infinites, 
