CHEMISTRY. 
The sulphuric acid unites itself to the earth 
of the bones, anti forms sulphate of lime ; by 
these means the phosphoric acid is disen- 
gaged, and remains in a free state in the 
liquor. The licpior is then to be decanted, 
and the residuum being washed, the water 
employed for this purpose must be added to 
the decanted liquor. The whole must then 
be evaporated, in order to separate the sul- 
phate of lime which crystallizes in silky fila- 
ments, and you will thus obtain phosphoric 
acid, under the form of white transparent 
glass; which, when reduced to powder, and 
mixed with a third of its weight of charcoal, 
and distilled, will yield good phosphorus. 
Phosphorus is found in almost every ani- 
mal substance, and in some plants, which, 
according to chemical analysis, have an ani- 
mal character. In this state it is generally 
combined with carbon, hydrogen, and azote, 
from which there result radicals with four 
bases. Phosphorus inflames at the temper- 
ature of 401 degrees. 
It has so great an affinity for oxygen, as 
to decompose oxygen gas. Example. A re- 
ceiver containing three or four quarts of oxy- 
gen gas (fig. 23) was placed over the mer- 
curial trough HC, and about 61^ grains of 
phosphorus distributed in the saucer I), and 
introduced under the receiver A, and kindled 
by means of a red-hot wire. The combus- 
tion took place with great rapidity, producing 
a brilliant flame, and the disengagement of 
a great degree of light and heat; the inside 
of the receiver became covered with -white 
light flakes, which were found to he concrete 
phosphoric acid. The quantity of oxygen 
gas employed was lb. 2 cubic inches; after 
the absorption there remained 23 cubic 
inches, of course 139 inches of gas was ab- 
sorbed. About 4.1 grains of phosphorus were 
burnt, and these combined with the oxygen 
formed the phosphoric acid. This experi- 
ment proves that, at a certain temperature 
oxygen has more affinity for phosphorus than 
it has tor caloric ; that, the phosphorus decom- 
poses the oxygen gas by seizing on its base ; 
and that the caloric passes into the surround- 
ing bodies, and produces in them heat. 
The following experiment, made on a 
larger scale, proves the'justness of the pre- 
ceding results in a manner more rigorous and 
exact. Take a large glass balloon, A (fig. 
27), the aperture of which, E F, is about 
three inches in diameter, and cover the aper- 
ture with a plate of ground glass, pierced 
with two holes to receive the two tubes, 
y .'/ !/, v x .r, furnished with cocks. Before 
you cover it with the plate, introduce into it 
a supporter, C B, with a porcelain cup, 1), 
containing 1303. grains of phosphorus; and 
after you have closely shut the balloon, by 
luting on the glass plate, exhaust the balloon 
of air by connecting the tube ,r.i' x with an 
air-pump. Then weigh the whole .apparatus 
by a nice balance, and fill the balloon with 
oxygen gas by means of the tube ?/ ?/ //, con- 
nected with a hydro-pneumatic machine. 
By the help of this machine you may ascer- 
tain in a verv accurate manner, the quantity 
of oxygen gas introduced into the balloon, 
and tint consumed during the course of the 
operation. 
When every thing is thus arranged, kindle 
the phosphorus by' meads of a burning glass; 
the combustion will be exceedingly rapid, 
and accompanied with a large flame and a 
Vol. I. 
Hydrogen — 
strong heat. In proportion as it is effected, 
there is formed such a quantity’ of white 
flakes, which attach themselves to the inside 
of the vessel, that it'is soon rendered entirely 
opake. 
When the whole apparatus has cooled, 
and you* have ascertained the quantity of 
oxygen gas employed, weigh the balloon 
again before you open it. Then wash, dry, 
and weigh, the small quantity of phosphorus 
remaining in the cup, in-order that it may 
he deducted from the whole quantity of 
phosphorus employed in the experiment. 
By observing these precepts, it will be easy 
to determine, 1st, the weight of the phos- 
phorus burnt ; 2d, the weight of the oxygen 
gas which lias combined with the phosphor- 
us ; 3d, the weight of the fiakes obtained 
by the combustion. This experiment will 
give nearly the same results as the pre- 
ceding. 
It thence appears that the phosphorus, in 
burning, combines itself with oxygen equal 
to one and a half of its own weight ; and 
that the weight of the white flakes, or con- 
crete phosphoric acid, produced, is equal to 
the sum of the weight of the phosphorus 
burnt, and that of the oxygen combined with 
it. 
Fhe combination of phosphorus not oxy- 
genated v th 
Degrees 
of oxygenation. 
C l, forms oxide of phosphorus 
Oxygen 7 2, — phosphorous acid 
(, 3, — phosphoric acid 
i phosphuret of hydro- 
' gen, or the base of 
1 phosphorized hydro- 
( gen gas 
Azote — phosphuret of azote 
Carbon — phosphuret of carbon 
Sulphur — phosphuret of sulphur 
t f phosphuret of iron, call- 
\ ed formerly siderit. 
Of Earths. — By analysing earths, and free- 
ing them from substances with which they 
are mixed, chemists have obtained nine 
simple or primitive earths, viz. lime, mag- 
nesia, barytes, alumina, silex, strontian, zir- 
conia, yttria, and glucina. 
Time is rarely found in a pure state ; it is 
contained in chalk, which may be deemed a 
neutral salt, being formed by the combination 
of lime with carbonic acid. The best process 
for obtaining lime in a state of purity is this: 
wash chalk in distilled water, brought to a 
state of ebullition, and then dissolve it in dis- 
tilled acetous acid : this acid, by combining 
with the lime, expels the carbonic acid, 
which escapes under the gaseous form ; then 
precipitate the lime by carbonate of ammonia, 
for the acetous acid’ abandons the lime, in 
order to combine with the ammonia, and the 
lime is precipitated : wash and calcine this 
precipitate, and the residuum will be pure 
lime. 
Lime is soluble in water, but in very small 
quantities ; more than BOO parts of w ater are 
necessary to dissolve one of it. It lias a 
pungent, hot, and acrid taste ; it turns blue 
vegetable colours green. It takes up water 
with avidity. When thrown into this liquid 
it splits, sw'dls up, acquires a larger volume, 
and a great heat. It dissolves in acids with- 
out effervescence. The borate of soda and 
the phosphates of urine dissolve it also. 
U u 
337 
Lime, when alone, is infusible, even 
though the fire may be urged by oxygen gas,, 
as has been proved by Lavoisier; but if 
combined with, acids, it forms a fusible body, 
for lime is a salifiable base. Of all these 
bases it is that most abundantly diffused 
throughout nature. See Li m e . 
Magnesia has never yet been found free= 
from every kind of foreign matter. To pro- 
cure it in the utmost degree of purity, cry- 
stals of the sulphate of magnesia (Epsom 
salt), of which it forms the base, must be dis- 
solved in distilled water, and decomposed 
by alkaline carbonates : the sulphuric acid 
combines with the alkalies; the magnesia 
with the carbonic acid, and is precipitated. 
I his precipitate must then be calcined, in 
order to disengage the carbonic acid ; and 
what remains wall be pme magnesia. 
Pure magnesia is exceedingly white, ten- 
der, and in appearance spongy. When per- 
fectly pure, it is not sensibly soluble in w ater. 
It excites no sensible savour on the tongue ; 
and in this respect it is greatly different from 
lime. It gives a light green colour to the 
tincture of turnsole. Lavoisier has proved 
by experiment that magnesia is as infusible 
as lime. See Magnesia, 
Barytes, or ponderous earth, has never 
yet been found pure and free from all com- 
bination. It is found under the pulverulent 
form, and exceedingly white. It gives a 
very slight tint of green to blue vegetable 
colours. Its specific gravity is from 4.2 to 
4.3000. Analysis lias proved that 100 parts 
of carbonate of barytes contain 62 of barytes, 
22 parts of carbonic acid, and 16 parts of 
water. See Barytes. 
Alumina or pure argil is found chiefly in 
the different kinds of clay, of w hich it forms 
the base,^ and where it is often mixed with 
silex. r l o obtain it very pure, sulphate of 
alumina (alum) must be dissolved in water, 
and afterw ards decomposed by alkaline car- 
bonates. The alkali combines with the sul- 
phuric acid, which then abandons the alu- 
mina ; anil the latter combines with the 
carbonic acid abandoned by the alkali. The 
alumina must then be freed from this acid 
by calcination; and after this process it will 
remain pure. It absorbs water with avidity, 
and becomes diluted in that liquid. It ad- 
heres strongly to the tongue. The.borate 
of soda and the phosphates of urine dissolve 
it. When exposed to heat, it becomes drv, 
shrinks, and cracks. By the action of the. 
fire it acquires so great hardness as to st rike 
fire with steel : it is then no longer suscep- 
tible of being diluted in wafer. Alumina, 
even when perfectly pure, is completely fu- 
sible in the fire, if urged by a current of 
oxygen gas. The result of its fus on is a 
vitreous, opake, and very hard substance, 
which scratches glass in the same manner as 
precious stones do. See Alum and Alu- 
mina. 
Silex, or vitrifiable earth, is almost in its 
state of purity in rock-crystal: but to have 
it perfectly pure, one part' of beautiful rock- 
crystal must be fused with four parts of pure 
alkali ; the mixture must then be dissolved 
in water, and precipitated by an excess of 
acid; the precipitate will be pure silex, 
which is rough and harsh to the touch ; its 
particles, when diluted in water, are easily 
precipitated. 
The fluoric acid dissolves silex exceedingly 
