C O B 
•planks which ftfise up the hatches higher 
than the rest of the deck, in which loop-holes 
for muskets to shoot out are usually made, in 
order to clear the deck when the ship is 
boarded by an enemy. 
COASTING, that part of navigation 
where the places assigned are not far dis- 
tant, so that a ship may sail in sight of land, 
or within soundings, between them. In this 
there are only required a good knowledge of 
the land, ancl the use of the compass and lead, 
or sounding-line. 
COAT, or coat of arms, in heraldry, a 
habit worn by the antient knights over their 
arms, both in war and tournaments, and Till 
borne by heralds at arms. It was a kind of 
surcoat, reaching as low as the navel, open 
at the sides with short sleeves, sometimes 
furred with ermine and hair, upon which 
were applied the armories of the knights em- 
broidered in gold and silver, and enamelled 
with beaten tin, coloured black, green, red, 
and blue : whence the rule never to apply 
colour on colour, or metal on metal. 
Coats of arms and banners were never al- 
lowed to be worn by any but knights and an- 
tient nobles. 
Coats, in a ship, are pieces of tarred can- 
vass put about the masts at the partners to 
keep out water. They are also used at the rud- 
der’s head, and about the pumps at the decks, 
that no water may go down there. 
COBALT, in mineralogy, a mineral of a 
grey colour, first discovered by Brandt, the 
celebrated Swedish chemist, in 1733. 
Bergman confirmed and extended the dis- 
covery of Brandt in the year 1780. In the 
year 1800 a new set of experiments were 
made upon it by the school of mines 'at Paris, 
in order to procure it perfectly pure, and to 
ascertain its properties when in that state. 
And in 1802 a new set of experiments were 
published by Thenard, which throw consi- 
derable light on its combinations with oxygen. 
1. 1. Cobalt is of a grey colour with a shade 
of red, and by no means brilliant. Its 
texture varies according to the heat em- 
ployed in fusing it. It is composed of 
plates, sometimes of grains, and some- 
times of small fibres adhering to each other. 
It has scarcely any taste or smell. 2. Its 
specific gravity, according to Bergman and 
the school of mines at Paris, is 7.7-; but Tas- 
saert makes it 8.5384. 3. It is brittle, and 
easily reduced to powder ; but if we believe 
Lconhardi it is somewhat malleable when 
red-hot. Its tenacity is unknown. 4. When 
heated to the temperature of 130 degrees 
Wedgevvood it melts ; but no heat which 
we can produce is sufficient to cause it 
to evaporate. When cooled slowly in a 
crucible, if the vessel is inclined the mo- 
ment the surface of the metal congeals, it 
may be obtained crystallized in irregular 
prisms. 5. Like iron, it is attracted by the 
magnet ; and from the experiments of Wen- 
zel it appears, that it may be converted into 
a magnet precisely similar in its properties to 
the common magnetic needle. 
II. When exposed to the air it undergoes 
no change, neither is it altered when kept 
. under water ; its affinity lor oxygen is not 
sufficiently strong to occasion a decomposi- 
! tion of the water. When kept red-hot in an 
open vessel it gradually imbibes oxygen ; 
and is converted into a powder at first blue, 
but which gradually becomes deeper and 
COB 
deeper, till at last it becomes black, or rather 
of so deep a blue, that it appears to the eye 
black. If the heat is very violent the cobalt 
takes fire, and burns with a red flame. From 
the experiments of Thenard it follows, that 
cobalt is capable of combining with three 
doses of oxygen at least, and of forming 
three distinct oxides, which may be exhibit- 
ed in a separate state. 
1 . The protoxide of cobalt has a blue co- 
lour. It may be obtained by dissolving co- 
balt in nitric acid, and precipitating the co- 
balt from the solution by means* of potass. 
The precipitate has a blue colour ; but when 
dried in the open air it gradually becomes 
black. This black powder is to be kept for 
half an hour in that degree of heat known to 
manufacturers of iron utensils by the name of 
cherry-red. This heat expels the oxygen 
which it had absorbed in drying, and converts 
it into a fine blue colour. This oxide dis- 
solves in acids without effervescence. The 
solution of it in muriatic acid, if concentrat- 
ed, is 'green ; but if diluted with water it is 
red. Its solution in sulphuric and nitric 
acids is always of a red colour. 2. When the 
protoxide of cobalt, newly precipitated from 
acids by potass, is exposed to the air, it gra- 
dually combines with an additional dose of 
oxygen, as Thenard ascertained by experi- 
ment, and assumes an olive-green colour ; 
and by cautiously drying it without the aid 
of heat, it may be obtained in that state. 
This is the deutoxide of cobalt. When this 
oxide is treated with diluted muriatic acid, a 
moderate heat developes oxymuriatic acid 
gas, and a red-coloured solution is obtained. 
Hence we see that the deutoxide of cobalt 
loses a portion of its oxygen during its solu- 
tion in muriatic acid. 3. When the protoxide 
or deutoxide of cobalt, newly precipitated 
from an acid, is dried by heating it in the 
open air, it assumes a flea-brown colour, 
which gradually deepens, till at last it be- 
comes black. This is the peroxide of cobalt, 
ft dissolves with effervescence in muriatic 
acid, and a great quantity of oxymuriatic 
acid gas is exhaled. Mr. Thenard considers 
the brown colour which the oxide of cobalt 
first assumes before it becomes black, as a 
tritoxide ; but his experiments are not suffi- 
cient to decide that, point. 
With respect to the reddish precipitate 
which is sometimes obtained by precipitating 
cobalt from acids, and which has been consi- 
dered as a peculiar oxide of cobalt, Mr. The- 
nard suspects, with reason, that it is a combi- 
nation of the oxide of cohalt with arsenic acid. 
III. 1. Cobalt does not combine with car- 
bon nor hydrogen. 2. It cannot be com- 
bined with sulphur by fusion. But sulphuret 
of cobalt may be formed by melting the me- 
tal along with sulphur previously combined 
with potass. It has a yellowish-white colour, 
displays the rudiments of crystals, and can 
scarcely be decomposed by heat. 3. Phos- 
phuret of cobalt may be formed by heating 
the metal red-hot, and then gradually drop- 
ping in small bits of phosphorus. It contains 
about one-fifteenth of phosphorus. It is 
white and brittle ; and when exposed to the 
air, soon loses its metallic lustre. The phos- 
phorus is separated by heat, and the cobalt is 
at the same time oxidated. This phosphuret 
is much more fusible than pure cobalt. 
IV. Cobalt does not combine with azotic 
gas, nor muriatic acid gas. 
3 B 2 
C O € 379 
\ . Cobalt seems capable of combining 
with most of the metals, but its alloys are 
very imperfectly known. 1. It combines with 
small portions of gold ; but the alloy scarcely 
differs from pure cobalt in its properties. 2. 
When two parts of cobalt and one of silver 
are melted together, the two metals are ob- 
tained separately after the process ; the silver 
at the bottom of the crucible, and the cobalt 
above it. Each of them, however, has ab- 
sorbed a small portion of the other metal i 
for the silver is brittle and dark-coloured, 
while the cobalt is whiter than usual. 3. The 
alloy of iron and cobalt is very hard, and not 
easily broken. Cobalt generally contains 
some iron, from which it is with great diffi- 
culty separated. 4. The alloy of tin and co- 
balt is of a light violet colour, and formed of 
small grains. 5. It was supposed formerly 
that cobalt does not combine with lead by 
fusion ; for upon melting equal parts of lead 
and cobalt together, both metals are found 
separate; the lead at the bottom, and the co- 
balt above. Indeed when this cobalt is melt- 
ed with iron, it appears that it had combined 
with a little lead; for the iron combines with 
the cobalt, aid the lead is separated. But 
Ginelin has shown that the alloy may be 
formed. He put cobalt in powder within 
plates of lead, and covered them with char- 
coal to exclude the air. He then applied 
heat to the crucibles containing the mixtures. 
Equal parts of lead and cobalt produced an aL 
loy, in which the metals appeared pretty uni- 
formly distributed, though in some places the 
lead predominated. It was brittle, and re- 
ceived a better polish than lead, which it re- 
sembled rather than cobalt; its specific gra- 
vity was 8.12. Two parts of lead and one of 
cobalt produced an uniform mixture, more 
like cobalt than lead, very little malleable, 
and softer than the last. Its specific gravity 
was 8.28. Four parts of lead and one of co- 
balt formed an alloy still brittle, and having 
the fracture of cobalt, but the polish of lead. 
It was harder than lead. Six parts of lead and 
one of cobalt formed an alloy more malleable, 
and hafder than lead. Its specific gravity 
was 9.65. Eight parts of lead and one of co- 
balt was still harder than lead, and it received 
a better polish. It was as malleable as lead. 
Its- specific gravity was 9.78. 
CCteCINELLA, in zoology, a genus of 
insects (see Plate Nat. Hist. fig. 132) of the 
order of coleoptera, the characters of which 
are these : the antennae are subclavated ; the 
palpi are longer than the antennas, the last ar- 
ticulation heart-shaped ; the body is hemi- 
spheric ; the thorax and elytra are margined; 
the abdomen is flat. This genus is divided 
into sections, from the colour of the elytra, 
and of the spots with which they are adorned. 
The females, impregnated by the males, de- 
posit their eggs, which turn to small larva?, 
slow in their process, and enemies to the 
plant-louse. Those larvae are frequently 
found upon leaves of trees covered with plant- 
lice. On the point of being metamorphosed 
they settle on a leaf by the hinder part of 
their body, then bend and swell themselves, 
forming a kind of hook. The skin extends, 
grows hard, and in a fortnight’s time the chry- 
salis opens along Hie back. The insect in its 
perfect state receives the impressions of the 
air, that gives its elytra a greater degree of con- 
sistence. It seldom flies, and cannot keep 
long on the- wing. Of all the different larva: of 
