CHA 
CHA 
Morveau and others, have pointed out the 
precise distinction. See Carbon. 
When charcoal is prepared in the usual 
way, by exposing wood in close vessels to 
a red heat, it always contains a portion of 
hydrogen. For if a quantity of this char- 
coal be exposed to a strong heat in a retort 
of porcelain, iron, or coated glass, a great 
quantity of gas is obtained. The gas which 
comes over first is a mixture of carbonic 
acid and heavy inflammable gas ; but the 
proportion of carbonic acid diminishes, and 
at last it ceases to come over at all ; yet 
the inflammable gas continues as copious 
as ever. The evolution of these gases was 
long ascribed by chemists to the water 
which charcoal usually contains, and which 
it is known to absorb from the atmosphere 
with considerable avidity. If that were 
the case, the proportion of inflammable gas 
ought to diminish at the same rate'with the 
carbonic acid; the hydrogen of the one 
being equally derived from the decompo- 
sition of water with the oxygen of the 
other. But as the evolution of inflammable 
gas continues after that of carbonic acid 
has ceased, it is scarcely possible to deny, 
that the hydrogen which thus escapes con-, 
stituted a component part of the charcoal. 
If, therefore, we consider the experi- 
ments of Morveau on the combustion of 
the diamond as decisive, we must conclude, 
that common charcoal is composed of three 
ingredients; namely, carbon, hydrogen, and 
oxygen. It is of course a triple compound. 
When common charcoal is exposed for 
an hour in a close crucible, to the stongest 
heat of a forge, it ceases to emit gas ; and 
no temperature is sufficient to expel gas 
from chai’coal thus treated. Desormes 
and Clement have endeavoured to demon- 
strate, that by this treatment common char- 
coal is deprived of the whole of its hydro- 
gen. The same • chemists tried the com- 
bustion of charcoal obtained from a variety 
of other substances exposed to the heat 
of a forge, as pitcoal, animat substances, 
and various vegetable substances, and found 
the products exactly the same. Hence 
they conclude that charcoal is in all cases 
the same, provided it be exposed to a 
heat strong enough ; and they conclude too 
that by this strong heat the whole hydrogen 
of common charcoal is expelled. 
These facts enable us to conclude, that 
there are two species of charcoal, namely; 
common and prepared charcoal. The first 
contains three ingredients, carbon, hydro- 
gen, and oxygen; the second is deprived 
of a portion of its hydrogen and oxyge'm 
It consists chiefly of carbon and oxygen 
united ; but it still retains a small portion 
of hydrogen, and is not, therefore, strictly 
speaking, a pure oxide of carbon, though 
it approaches veiy nearly to such an oxide. 
CHARGE, in gunnery, the quantity of 
gunpowder and ball wherewith a gun is 
loaded for execution. The role for charg- 
ing large pieces in war arc, that the piece 
be first cleaned or scoured within side ; 
that the proper quantity of powder be next 
driven in and rammed down : care however- 
being taken, that the powder in ramming 
be not bruised, because that weakens its 
effect ; that a little quantity of paper, hay, 
lint, or the like, be rammed over it ; and 
that the ball or shot be intruded. If the 
ball be red-hot, a tampion, or trencher of 
green wood is to be driven in before it. 
The weight of the powder necessaiy for a 
charge is commonly in a subdnple propor- 
tion to that of the ball. 
Charge, in heraldry, is applied to the- 
figures represented on the escutcheon, by 
which the bearers are distinguished from 
one another ; and it is to be observed, that too- 
many charges are not so honourable as fewer. 
CHARGED, in heraldry, a shield cari-y- 
ing some impress or figure, is said to be 
charged therewith ; so also when one bear- 
ing, or charge, has another figure added 
upon it, it is properly said to be charged. 
CHART, or hydrographical rmp, in na- 
vigation, is a representation, in piano, of 
a part, or of the w-liole of the water on the 
surface of the globe, and the adjacent coast. 
There are various kinds of charts, as Glo- 
bular, Plane, Mercator’s, &c. 
Chart, globular, is a projection so called 
from the conformity it bears to the globe 
itself. This projection was proposed by 
Senex, in which the meridians are inclined, 
tlie parallels equidistant and curvilinear, 
and the rhumb-lines real spirals, as on the 
surface of the globe. From this last pro- 
perty, it is evident it can be of very little 
use in navigation ; as a map, however, it 
has its advantages. 
Construction of Charts. 
I. Of the plane chart . — The number of 
degrees of latitude which the chart is in- 
tended to contain, and tlie extent from 
east to west being fixed upon ; a line is to 
be drawn near the side or end of a sheet 
of paper, in length equal to the whole 
lengtli of the chart from north to south ; 
and this line is to be divided into degrees 
