200 
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beech. This mixture being moiftened with half a pint 
ot water, is introduced into a HefTian retort; the matter 
is affayed, by making a portion red-hot in a crucible: 
if it emit a violent flame, with a fmell of garlic, it is a 
proof that phofphorus will be afforded. The retort is 
placed in a furnace built on purpofe, and a large receiver 
is adapted, one-third full of water; the receiver muff 
have a fmall hole pierced in it; and M. Hellot confiders 
this as one of the moll neceffary circumftances to enfure 
fuccefs. Three or four days after the apparatus has been 
put together, a fire is made fo as very gradually to dry 
the furnace and the lutes. The fire is raifed by degrees 
to the moft extreme heat, and kept up -in that Rate from 
fifteen to twenty hours; the phofphorus does not come 
over till about fourteen hours after the commencement 
of the operation, which in the whole lafls twenty-four 
hours. A large quantity of ammoniacal carbonat firft 
riles, which is partly difl'olved in the water of the re¬ 
ceiver: the volatile or aeriform phofphorus, firft pafles 
in luminous vapours; the true phofphorus next comes 
over, in the form of an oil, or refembling melted wax. 
When no more pafles over, the apparatus is left to cool 
for two days ; the receiver is then unluted, and water is 
added to lool'en the phofphorus adhering to the fides; 
the phofphorus is then melted in boiling water, and cut 
into fmall pieces, which are introduced into the necks 
of matraffes, cut towards the middle of the body in the 
form of a funnel, and plunged in boiling water; the 
phofphorus melts, is purified, and becomes tranlparent, 
by the feparation of a blackifh matter, which rifes to the 
top; it is afterwards plunged in cold water, by which it 
is rendered folid. 
Modern chemifts obtain phofphorus by decompofing 
calcareous phofphat with fulphuric acid, &c. When the 
phofphat is very pure, it is tranlparent, and of a conflu¬ 
ence like wax. In order to mould the phofphorus into 
flicks, take a long-necked funnel, or tube ; flop the ori¬ 
fice with a cork or bit of wood; fill it with water, and 
put in the phofphorus ; plunge the tube into boiling wa¬ 
ter, and the phofphorus will melt and run ; then plunge 
the tube into cold water; and, when the phofphorus is 
congealed, take away the cork, and pufti it out of the 
tube or mould with a fmall flick or rod. Pelletier con¬ 
trived the following method: Take a tube about feven 
inches long, with an aperture not too large to be clofed 
with the top of the fore-finger; melt the phofphorus in 
boiling water, then immerle one end of the tube, hold¬ 
ing the other end in the mouth; make a flight infpira- 
tion, that the phofphorus may rife in the tube, but flop 
the moment the phofphorus is within an inch of your 
mouth ; then flop the end of the tube with your finger, 
and plunge it into an earthen pan full of cold water; the 
pholphorus will foon congeal, and, by a flight fhake, may 
be driven out of the tube. 
In breaking a flick of phofphorus, the elements of cryf- 
tallization are fometimes apparent; but, to obtain it cryf- 
tallized in oflahedrons, it mull be difl'olved in water of 
31 or 32* temperature; as it congeals, prick it, and let 
the ftill-liquid phofphorus run out: the refult is a mafs 
of cryflals in needles. Pelletier alfo obtained cryftal- 
.Hzed phofphorus from its l'olution in a volatile oil, by 
cooling only, or in adding alcohol to the folution ; and 
at length a precipitate was formed, which was of eight 
lides with the upper and lower angle blunted. The phof¬ 
phorus fhould always be melted under water. By put¬ 
ting it under water for melting, the temperature of its 
fufion may be eflimated. To preferve phofphorus, it 
fhould be kept under water and without light; for, when 
expofed to the light, it becomes covered with a red pel¬ 
licle ; this is a beginning of combultion or oxydation. 
Ip preferving pholphorus under water, care mull be taken 
that it be not aerated. 
Phofphorus, when extrafled from the fubllances which 
contain it, is commonly dirty and impure; it contains 
charcoal-d ult and phofphorus half burnt; which gives it 
S T R Y. 
a red or brown colour. To obtain it pure, it fhould be 
melted, and paffed feveral times through chamois-leather 
in hot water: the leather can ferve only once, as the fe- 
cond parcel of pholphorus put into it would be coloured 
by it. Phofphorus volatilifes eafily in diftillation with 
water; it becomes liquid, and rifes in vapour, with the 
heat of boiling water. It may be diftilled by filling the 
veflels previoufly with carbonic acid, or any other gas 
not proper for maintaining combuflion. 
The various colours under which phofphorus is ob¬ 
tained, arife from the greater or lels quantity of oxygen 
it has abforbed, but yet not to become acid : this is oxyd 
of phofphorus. To feparate the phofphorus from its 
oxydated part, put a given quantity of it into a tube, 
- which plunge into hot water; the phofphorus melts, and 
the oxyd floats on the furface, provided the oxydated 
portion is not foluble in the fame degree of heat. This, 
therefore, exhibits another mode of purifying phofphorus. 
If phofphorus be expofed to atmofpherical air, it burns 
flowly, and exhales fntoke all over its furface ; this va¬ 
pour, which gives out a itrong fmell of garlic, is phof¬ 
phorus acid. Put each cylindrical flick of phofphorus 
into a little glafs tube, whole extremity is clofed funnel- 
fafhion, with a fmall aperture for the palfage of the little 
drop of acid which is produced : prepare feveral of thefe 
tubes, and pat them into a large funnel under a bell- 
glafs or jar, as reprefented in the Chemiftry Plate II. 
fig. 16. Place this in a difh containing water, and cover 
the whole with a large glafs dome, with apertures at the 
fides, that the duft may not fall upon it, and alfo to keep 
the air moift, which greatly forwards the decompofition 
or infenfible combuflion of the phofphorus. 
Take a tube of glafs, clofed at one end, about fixteen 
inches long and half an inch thick, widened at bottom 
that it may (land firm. Introduce into it a fmaller tube, 
at the end of which fallen a Hick of phofphorus." Place 
the apparatus over water. The phofphorus takes up all 
the oxygen of the air; and the azot, which melts the 
phofphorus, does not unite with it, but holds a part of 
it in folution, which even catches fire at once, if not 
kept in a proper temperature. This is Berthollet's eu¬ 
diometer. The prefence of the phofphorus, thus held in 
folution by the azot, may increal'e the volume fo as 
caule l'ome miltake in experiments with the eudiometer, 
if you only verify the volumes without proving alfo the 
weights. 
Take a tube of glafs or cryflal, of an inch in diameter 
and fix inches long, clofed at its upper end, and widened 
at the lower extremity. Fill this with mercury, and put 
in a little phofphorus, which, having lefs fpecific gravity, 
rifes to the upper part of the tube; melt the phofphorus 
by means of a lighted coal applied on the outfide of the 
tube; then introduce into the tube the fmall portions of 
air to be wrought upon, which have been previoufly gaged 
in a jar graduated for that purpofe. The combuflion con¬ 
tinues till the end of the operation ; but, for greater ex- 
attitude, heat the refidue very llrongly; and, when cold, 
pafs it into a little jar gaged at the fame time with the 
firll: the difference in the two volumes (hews the quan¬ 
tity of oxygen gas which the ait contained that was ufed 
in the experiment. This is the whole artifice of Seguin’s 
eudiometer. 
Humboldt has lately proved, by a great number of ex¬ 
periments, 1. That phofphorus, whether it be burnt or 
nearly made lucid in contact with atmofpherical air, is 
an eudiometrical fubflance extremely irregular and un¬ 
certain, flnee oftentimes it abforbs only o - i5 to o‘2o of 
oxygen, inftead of o'T.'j ; and the fame gas efl'ayed in 
different tubes gives different refults. That nitrous 
gas dilcovers almoft conllautly fome hundredth parts of. 
oxygen in the refiduum of the phofphoric eudiometer. 
3. That all azotic gafes, in which phofphorus throws out 
no light, and which do not decreafe in volume with ni¬ 
trous gas, cannot be confidered as devoid of oxygen. 
There are cafes where 0-13 of oxygen remain concealed 
