PAL 
P A N 
PAN 
349 
united with the different metals, and formed 
alloys; the properties of which have been 
described by Mr. Chenevix. 
When exposed to the action of melted 
potass, it loses its brilliancy, and a little of its 
weight. Soda acts with less violence. When 
ammonia is kept over it for some days, it ac- 
quires a blue colour. 
Sulphuric acid, when boiled upon palladi- 
um, acquires a line red colour, and dissolves 
a portion of it; but its action is not very pow- 
Ciful. Nitric acid acts with much greater 
energy, and oxydizes and dissolves it, for , ing 
a very beautiful red solution. Muriatic acid, 
when long boiled upon it, becomes of a beau- 
tiful red colour. Nitro-muriatic acid attacks 
it with great violence, and forms a fine red 
solution. 
The alkalies and earths throw down a fine 
orange powder from these solutions ; and 
when ammonia is used, the supernatant li- 
quid is sometimes of a fine greenish blue. 
Sulphat, nitrat, and muriat of potass and of 
ammonia, throw down orange precipitates, as 
they do from the solutions of platinum. Mu- 
riat of tin throws down a dark orange or 
brown precipitate from neutralized salts of 
palladium. Sulphat of iron throws down 
palladium in the metallic state. Prussiat of 
potass occasions an olive-coloured precipi- 
tate, and water containing sulphureted hy- 
drogen gas a dark brown one. Fluoric, 
arsenic, phosphoric, oxalic, tartaric, citric 
acids, and their salts, precipitate some of the 
solutions of palladium, and form various com- 
pounds with it. 
Such are the properties of palladium ascer- 
tained by Mr. Chenevix. They indicate a 
substance different from every other known 
metallic body. Still he considered the sub- 
stance as a compound, and tried various ways 
of forming one similar. i\t last he suspected 
mercury and platinum as likely lobe its con- 
stituents ; and alter various trials, hit upon 
the following mode of forming it, which suc- 
ceeded : 
One hundred parts of platinum, previously 
purified by solution in nitro-muriatic acid, 
and precipitation by sal ammoniac, were dis- 
solved in nitro-muriatic acid. To the solu- 
tion 200 grains of red oxide of mercury were 
added. These not saturating the excess of 
acid, he continued to add more till the acid 
was saturated. A solution of sulphat of iron 
was put into a long-necked matrass; the 
mixed solution of platinum and mercury was 
poured into it, and the matrass heated on a 
sand bath. A copious precipitate soon fell, 
and the inside of tiie matrass was coated with 
a thin metallic crust. This crust, collected 
and washed, was put into a charcoal crucible, 
and exposed to a violent heat ; a button of 
metal was obtained, which possessed the pro- 
perties of palladium. From the proportions 
employed, Mr. Chenevix concluded, that 
palladium is composed of two parts of pla- 
tinum, and one of mercury. 
The extraordinary consequences that fol- 
low from this experiment will occur at once 
to the reader, Here is a compound of two 
metals, which cannot be decomposed by art 
And if we know one such compound, why 
may not many of the other supposed metals 
be such compounds ? 
We have here a compound containing mer- 
cury, one of the most volatile substances in 
nature, in such a state as to resist the most 
violent heat without quitting its combination: 
so that one of the most apparently whimsical 
of all the alchymistical opinions is here veri- 
fied. 
But the specific gravity of palladium is one 
of the most extraordinary circumstances. It 
is considerably less than that of the lightest of 
its component parts. The specific gravity of 
platinum cannot be stated at less than 22. 
'Flic specific gravity of mercury may be 
stated at 13.5 ; but the actual specific gravity 
was only \ 1.2. So that an expansion amount- 
ing to more than a third of the whole has 
taken place. 
The experiments of Mr. Chenevix were 
repeated by some of the eminent chemists in 
London ; among others, by Dr. Wollaston 
and ' Mr. Tennant : but these gentlemen 
could not succeed in obtaining palladium. 
Hence doubts are still entertained by some 
concerning the composition of this substance. 
But the well-known precision of Mr. Chene- 
vix, and the uncertainty which he has himself 
pointed out of succeeding in a few trials, 
ought to induce us to give him full credit. 
Dr. Thompson tried the experiment with all 
the precautions he could think of to ensure 
success. The metallic crust announced by 
Mr. Chenevix was formed ; and upon heat- 
ing it violently in a charcoal crucible, a but- 
ton was obtained of a white colour, ami very 
like platinum. It was very porous, and there- 
fore though malleable, it soon broke under 
the hammer. Its specific gravity was only 
1 1. 126. But this was partly owing to its 
porousness. It was acted upon by the three 
mineral acids; but the action of neither of 
them was violent, and the solution, instead 
of red, was a dirty reddish-brown. He could 
detect no iron by the usual tests ; but the so- 
lutions gave unequivocal marks of the pre- 
sence ot platinum. In short, the button was 
not platinum, but at the same time it was not 
palladium. 
PA LASS [A, a genus of the syngenesia po- 
lygamia frustranea class and order. 'The re- 
ceptacle is chaffy; down none; seeds verti- 
cal; margin ciliated; calyx imbricate. r l here 
is one species, a shrubby plant of Lima. 
PALLET, in heraldry, is nothing but a 
small pale. 
Pallet. See Watch. 
PALM, a measure of length, about three 
inches. 
PALPITATION. See Medicine. 
PALSY. See Medicine. 
PALY, or Pale, in heraldry, is when the 
shield is divided into four or more equal 
parts, by perpendicular lines falling from the 
top to the bottom. 
PANARY FERMENTATION. See 
Fermentation. 
PAN AX, Ginseng, a genus of the di- 
cecia order, in the polygamia class of plants. 
In the umbel the corolla is tive-petalled ; 
stamina rive; hermaphrodite calyx five- 
toothed; superior styles two; berry two- 
seeded; male calyx entire. 'There are nine 
species of this plant: 1. Quinquefoliav 2. 
Trifolia. 3. Fruticosa. 4. Arborea. 5. 
Spinosa. 6. Aculeata. 7. Chrysophylla. 
8. Simplex. 9. Attenuata. 
Ginseng was formerly supposed to grow 
only in Chinese Tartary, affecting mountain- 
, ous situations, shaded by close woods : but it 
has now been long known that this plant is 
also a native of North America, whence M. 
Sarrasin transmitted specimens of it to Paris 
in the year 1704; and the ginseng since dis- 
covered in Canada, Pennsylvania, and \ ir- 
giii’.a, by Lafiteau, Kalm, Bartram, and others, 
lias been found to correspond exactly with 
the 'l artarian species ; and its roots are now 
regularly purchased by the Chinese. 
l he dried root of ginseng, as imported 
here, is scarcely the thickness of the little 
finger, about three or four inches long, fre- 
quently forked, transversely wrinkled, of a 
horny texture, and hot' internally and ex- 
ternally of a yelknvish-wi .te colour. On the 
top are commonly one or more little knots, 
which are the remains of tiie stalks of the 
preceding years, and from the number of 
which the age of the root is judged of. “To 
the taste it discovers a mucilaginous sweet- 
ness, approaching to that of liquorice, ac- 
companied with some degree of bitterness, 
and a slight aromatic warmth, with little or 
no smell. It is far sweeter, and of a more 
grateful smell, than the roots of fennel, to 
which it has by some been supposed similar ; 
and differs likewise remarkably from those roots 
in the nature and pharmaceutic properties of its 
active principles, the sweet matter of the gin- 
seng being preserved entire in the watery as 
well as the spirituous extract, whereas that of 
fennel-roots is destroyed or dissipated in the 
inspissation of the watery tincture.. The 
slight aromatic impregnation of the ginseng 
is likewise in good measure retained in lhe 
watery extract, and perfectly in the spiritiL- 
ous.” 
'J’iie Chinese ascribe extraordinary virtues 
to the root of ginseng; and have long con- 
sidered it as a sovereign remedy in almost ail 
diseases to which they are liable - , having no 
confidence in any medicine unless in combi- 
nation with it. It is observed by Jartoux, 
that the most eminent physicians in Chinas 
have written volumes on the medicinal pow- 
ers of this plant. We know, however, of no> 
proofs of the efficacy of ginseng in Europe z 
and from its sensible qualities, we judge it to- 
possess very little power as a medicine. 
PANCRATIUM, a genus t-lie liexan-- 
tiria monogynia class of plants, the flower of 
vvlreh consists of six l'anceolated petals ; its 
nectarium is twelve-cleft; stamina placed on 
the nectary. There are ten species, beauti- 
ful dowering plants, with large bulbs-. 
PANCREAS. See Anatomy. 
PAN DAN LS, a genus of the dicrcia m<*- 
nandria class and order. There - is no caivx 
or corolla; male anther sessile ; female stig- 
mas two p fruit compound. There is oue 
species-. 
PANDECTS, in the civil law,, collections - - 
made by Justinian’s order, of five hundred 
and thirty -four decisions of the antient law- 
yers, on so many questions occurring in the* 
civil law; to which that emperor gave the- 
force and authority of law, by an epistle pre- 
fixed to them. The pandects consist of fifty- 
books, and make the first part of tiie body 06 
the civil law. See Civil Law. 
PANEL, inlaw. See Jury. 
PANICUM, a genus of the digynia order, 
in the tviandria class- of plants. Tiie calyx is; 
trivalved, the third valvule being very small.. 
The species are in number seventy-nine, 
grasses of different countries. 
PANN.EL, in law. See Panel. la the 
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