DIA 
jolaced with it in the muffle. Wlien botli 
were perfectly red throughout, the pyrome- 
ter was withdrawn, and indicated 13° of 
Wedgwood’s scale. They were replaced, 
and the heat increased until the glow ap- 
peared ; it was kept at this as equal as pos- 
sible until the diamond was consumed j the 
pyrometrical piece then indicated 14°, and 
in another diamond the heat requisite to 
produce the glow, and consume it, was 15°. 
These experiments are evidently the most 
accurate that have been made to ascertain 
this point ; and indeed the temperature as- 
signed by Guyton were rather from conjec- 
ture than experiment. Although they shew 
that a less elevation of temperature is re- 
quisite for the combustion of the diamond 
than was supposed, they still prove it to be 
much higher than that which is requisite for 
the combustion of charcoal. 
Sir George Mackenzie, likewise, re- 
peated and confirmed an experiment of the 
French chemists, in which a piece of soft 
iron was converted into steel by being 
heated with diamonds, in the same manner 
as it would have been by being heated in 
the usual manner with charcoal powder ; 
and his experiments are more satisfactory, 
as having been made with diamond in its 
ptirest state. (Nicholson’s Journal, 4to. 
vol. iv. p. 103.) 
The diamond is scarcely acted on by any 
other agent than by oxygen, at an elevated 
temperature. Bergman states an experi- 
ment, from which it would appear to be 
capable of being partially oxyded by sul- 
phuric acid ; this acid, when poured on the 
diamond pow'der, previously freed from 
impurities by digestion with nitro-miiriatic 
acid, and evaporated to a small quantity, 
becoming black, and depositing small pel- 
licles, which take tire on the approach of 
flame, and are consumed. The other acids, 
according to his observation, exert no sen- 
■sible action on it j nor does it appear from 
tlie experiments he made with soda (the 
mixture of soda and of diamond powder 
being exposed to a very strong heat) that it 
had suffered any chemical change from the 
action of the alkali ; for though a minute 
portion of earthly matter appeared to be 
produced, this might probably be derived 
from the various -agents which W'ere em- 
ployed in the experiments. (Essays, vol. ii. 
p. 118.) 
Diamond, in the glass trade, an in- 
strument used for squaring the large plates 
or pieces ; and, among glaziers, for cutting 
their glass. 
VOL. II. 
DIA 
These sorts of diamonds are differently 
fitted up ; that used for large pieces, as 
looking-glasses, &c. is set in an iron ferril, 
about two inches long, and a quarter of an 
inch in diameter ; the cavity- of the ferril 
being filled up with lead, to keep the 
diamond firm : there is also a handle of 
box, or ebony, fitted to the ftrril, for 
holding it by. 
Diamond, in heraldry, a term used for 
expressing the black colour in the achieve- 
ments of peerage. Guillim does not ap- 
prove of blazoning the coats of peers by 
precious stones instead of metals and co- 
lours; but the English practice allows it. 
Morgan says the diamond is the emblem of 
fortitude. 
DIANjE arbor, or Alt BOR hince, in che- 
mistry, the beautiful crystallizations of sil- 
ver, dissolved in nitrous acid, to which some 
quicksilver is added ; and so called from 
their resembling the trunk, branches, 
leaves. See. of a tree. This elegant arrange- 
ment, however, of tlie particles of silver is 
not peculiar to this state or menstruum, 
since copper filings dropped into the solu- 
tion of silver in aqua tbrtis, is found to 
have the same effect, when viewed by the 
microscope: nay, the silver ores are fre- 
quently found ramified in the same manner. 
DIANDRIA, the name of the second 
class in Linmeus’s sexual system, consisting 
of hermaphrodite plants, which, as the 
name imports, have flowers with two sta- 
mina or male organs. The orders in this 
class are three, derived from the number of 
styles or female parts. Most plants, with 
two stamina, have one style, as jessamine, 
lilac, privet, veronica, and bastard alater- 
nns. Vernal grass has two styles ; pepper 
three. 
DIANTHERA, in botany, a genus ofthe 
Diandria Monogynia class and order. Na- 
tural order of Personatae. Acanthi, Jus- 
sieu. Essential character : corolla rin- 
gent ; capsule two-celled, bursting with an 
elastic nail ; stamina each a pair of alter- 
nate anthers. There are twelve species, 
of which D. americana is a low herbaceous 
plant, with a perennial root, which sends 
out several weak stalks about four inches 
long. The leaves are hairy, sessile, and of 
a dark green colour, and an aromatic 
odour. The flowers are produced from the 
side of the stalks in small spikes, and are in 
shape and colour very like those of clino- 
podium. They come out in July, but rarely 
produce seeds in England. It is a native 
of Virginia. 
Kk 
