3D I A 
D I A 
ID I A 
51.0 
Explanation. 
The numbers in the first horizontal line are 
■units, and those in the first vertical column 
tens ; the .other numbers, under the one, and 
opposite to the others, are the respective dia- 
meters of shot and calibers. Thus, to 'find 
the diameter of the shot, and the caliber of a 
24-pounder, look for the number 2 on the 
left-hand side, and for 4 at top ; then the 
number 5.547, under 4, and opposite 2, will 
be the diameter of the shot in inches and de- 
cimals, and the number 5824, under the first, 
the c aliber of a 24-pounder, &c. 
Diameters of leaden bullets from 1 to 29 in the pound. 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
0 
0 
1.671 
1 .326 
1.158 
1.05 
.977 
.919 
.873 
.835 
.803 
1 
.715 
.51 
.730 
.711 
.693 
.677 
.663 
.650 
.637 
.626 
2 
.615 
.605 
.596 
.587 
.579 
.571 
.564 
.557 
.550 
.544 
3 
.538 
.536 
.526 
.521 
.517 
.511 
.506 
.501 
.497 
.493 
The diameter of musket-bores differs about 
1-5 0th part from that of the bullet. The 
government allows 1 1 bullets in the pound 
i'or the proof of muskets, and 14 in the pound, 
or 29 in two pounds, for service ; 1 7 lor the 
proof of carbines, and 20 for service ; 28 in 
the pound for proof of pistols, and 34 for ser- 
vice. 
Diameter of a curve , is a right line AC 
{Plate Miscel. fig. 42.) bisecting the right 
lines DE, DE, drawn parallel to one 
another ; and either of a finite or infinite 
length. Though a right line, bisecting all 
parallel lines drawn from one point of a curve 
to another, is taken in a strict sense only for 
the diameter of a curve line, yet it may not 
be amiss more generally to define a diameter 
in saying that it is that "line, whether right or 
curve, which bisects all parallels drawn from 
one point of a curve to another, so that, ac- 
cording to this, every curve will have a dia- 
meter: and thence sir Isaac Newton’s curves 
of the second order have all either a right- 
lined diameter, or else the curves of some 
one of the conic sections for diameters ; and 
many geometrical curves of the higher or- 
ders may also have for diameters curves of 
more interior ones, and that ad infinitum. 
See Curve. 
Diameter of a sphere, is the diameter of 
the semicircle, by whose rotation the sphere 
is generated ; in which sense it is the same 
■with axis. See Axis. 
Diameter of gravity, in any surface or 
solid, is that line 'in which the centre of gra- 
vity is placed. See Center of gravity. 
Diameter, in astronomy. The diame- 
ters of the planets are either apparent or real: 
the apparent diameters are such as they 
appear to the eye ; and being measured by a 
micrometer, are found different in different 
circumstances and parts of their orbit. See 
Astronomy. 
The mean apparent diameters of the pla- 
nets, as seen from the sun, are as follow : 
Merc. Yen. Ear. Moon Mars Jup. Sat. Her. 
20" 30" 17" 6" 11" 37" 16" 4" 
DIAMOND, is a precious stone, which 
has been known from the remotest ages. 
When pure, it is perfectly transparent like 
crystal, but much more brilliant. Its figure 
varies considerably ; but most commonly it 
is crystalized in the form of a six-sided prism, 
terminated by a six-sided pyramid. It is the 
hardest of all bodies ; the best-tempered steel 
makes no impression on it. Diamond-pow- 
der can only be obtained by grinding one 
diamond against another. Its specific gra- 
vity is rather more than 3.5. It is a non- 
conductor of electricity. 
As the diamond is not affected by a consi- 
derable heat, it was for many ages consider- 
ed as incombustible. Sir Isaac Newton, ob- 
serving that combustibles refract light more 
powerfully than other bodies, and that the 
diamond possesses this property in great per- 
fection, suspected it, from that circumstance, 
to be capable of combustion. This singular 
conjecture was verified in 1694 by the Flo- 
rentine academicians, in the presence of 
Cosmo III. grand duke of Tuscany. By 
means of a burning-glass, they consumed se- 
veral diamonds. Francis I. emperor of Ger- 
many, afterwards witnessed the destruction 
of several more in the heat of a furnace. 
These experiments were repeated by Rou- 
elle, Macquer, and Darcet; who proved that 
the diamond was not merely evaporated, but 
actually burnt; and that if air was excluded, 
it underwent no change. 
No attempt, however, was made to ascer- 
tain the product till 1772. Lavoisier, in a 
Memoir published that year, ' shewed that 
when the diamond is burnt, carbonic acid 
gas is obtained, and that there is a striking 
analogy between it and charcoal. In 1785, 
Guyton-Morveau found that the diamond is 
combustible when dropped into melted nitre; 
that it burns without leaving any residuum, 
and in a manner analogous to charcoal. This 
experiment was repeated with more preci- 
sion by Mr. Tennant in 1797. The conclu- 
sion which he drew from it was, that when a 
diamond is burnt the whole of the product is 
carbonic acid gas ; that a given weight of 
diamond yields just as much carbonic acid 
gas as the same weight of charcoal; and that 
diamond and charcoal are both composed of 
the very same substance. The conclusion 
that diamond is nothing else than charcoal, 
was directly contrary to what one would 
have expected from comparing the two sub- 
stances together. Their colour, hardness, 
specific gravity, and electrical properties, are 
exceedingly different ; nor do they resemble 
each other more nearly in their combustibi- 
lity. Charcoal takes fire at a red heat; and 
when once kindled in oxygen gas continues 
to burn till it is wholly consumed. Accord- 
ing to Morveau, the diamond, before it can 
be burnt, must be exposed to the sun’s rays 
in the focus of a large burning glass, or to a 
heat not under 5000°. But. sir George 
3 T 2 
MffCenzle found that diamonds will burn in 
a muffle, when heated no higher than 14° ot 
1 5° Wedgewood ; which must be consider- 
ably lower than 5000° Fahrenheit. Its sur- 
face assumes a black colour like charcoal: 
this crust is soon wasted, and another is form- 
ed in its place. It was in this manner that a 
diamond weighing 3.089 grains troy, gradu- 
ally wasted away completely when exposed 
by Morveau for one hour and 40 minutes in 
the focus of the celebrated burning glass of 
Tschirnhausen, while a thermometer exposed 
to the sun stood at 104°. 
Morveau found that one part of diamond 
during its combustion combines with 4.592 
parts of oxygen, and the carbonic acid gas 
formed amounts to 5.592 parts : consequent- 
ly, carbonic acid gas is composed of one part 
of diamond and 4.592 of oxygen; or, which 
is the same thing, 100 parts of carbonic acid 
gas are composed of 
17.88 diamond 
82. 12 oxygen 
100.00 
But Lavoisier ascertained that one part of 
charcoal, when burnt, combines with 2.5714 
parts of oxygen, and forms 3.5714 parts of 
carbonic acid gas: consequently, 100 parts 
of carbonic acid gas are composed of 
28 charcoal, 
72 oxygen. 
100 . 
But 100 parts of carbonic acid gas are alse 
composed of 17.88 diamond, and 82.12 oxy- 
gen. We have therefore this equation: 
Diamond. Oxygen. Char. Oxygen, 
17.88 -f 82.12 = 28 + 72. 
Consequently, subtracting 72 parts of oxygen 
from both sides of the equation, we have 
Diamond. Oxygen. 
17.88 -f- 10.12 = 28 charcoal. 
That is to say, 28 part? of charcoal are com- 
posed of 17.88 diam ond and 10.12 oxygen. 
Of course, 100 parts of charcoal are com- 
posed of 
63.85 diamond, 
36.15 oxygen. 
100.00 
Thus we see why diamond and charcoal 
possess different properties : the one is a 
simple substance ; the other is a compound 
of the diamond and oxygen, or it is what the 
French chemists • call an oxide of diamond. 
The diamond, then, is that substance in a 
state of purity to which Lavoisier and his as-\ 
sociates gave the name of carbon ; charcoal 
is not carbon, as they supposed, but the oxide 
of carbon. 
Diamond-mines are found only in the East 
Indies, and in Brazil in South America ; in 
the kingdoms of Golconda, Visapour, Ben- 
gal, and the island of Borneo. There are 
four mines, or rather two mines and two 
rivers, whence diamonds are drawn. 1. The 
mine of Raolconda, in the province of Car- 
natica, five days journey from Golconda, and 
eight from Visapour, which has been disco- 
vered about 200 years. 2. That of Gairi, 
or Coolour, seven days journey from Gol- 
conda eastwardly. It was discovered 140 
years ago by a peasant, who, .digging in' the 
