252 C H E M I 
that quantity. But, as there are only o’17 of this acid 
difengaged, and as 0-24. ftill remains clofely united with 
the lime, thefe o'17 can yield but 0-06 of phofphorus; 
thus more than two-thirds of the phofphorus contained 
in the waters are loft ; and, after the diftiliation of their 
acid obtained in the ufual way by charcoal, the refidue 
contains 0-59 of phofphat of lime not decompofed. Thefe 
explanations therefore lead us to prefer the procefs of 
Fourcroy and Vauquelin, as follows : 
Evaporation of Acid. Liquors, and their Mixture 'with 
Povoder of Charcoal. —When the matter has been macerat¬ 
ed, as mentioned before, draw off the clear liquor ; wafh 
the remaining thick fluff in river-water feveral times; 
unite thefe waters with the fir ft, and evaporate in pots of 
copper, or rather of lead. During the evaporation of 
this liquor, there will be feparated a confiderable quan¬ 
tity of fulphat of lime, held in folution by means of the 
phofphoric acid ; this may be taken away by decanting af¬ 
ter ithasfettled ; butthe phofphoric acid will always retain 
a certain quantity of it, which cannot be feparated but 
by operations very complex and coftly. 
The phofphoric acid commonly appears as a mafs of 
a white colour, flightly tinged with yellow, formed of 
little fhining lcales like pearls; this is called concrete phof¬ 
phoric acid ; but it is not pure, containing ftill a good 
deal of lime. With this acid they make phofphorus. To 
extradt the phofphorus from the phofphoric acid, mix it 
with one fourth of its weight of charcoal in powder, and 
dry the mixture in a melting-pot, till the greateft part 
of the moifture is gone. 
Pelletier’s method is to bring the acid liqudrs to a thick 
confidence; then add the powdered charcoal, previoufly 
calcined till the matter is friable: continue the drying, 
but ftir it frequently to prevent it from being grumous ; 
and keep up the fire till the bottom of the veflel be red- 
hot. The veffel fhould have a very thick bottom, and 
be well luted on the outfide, or the fire may calcine it. 
Diftiliation of Phofphorus. —Fill a ftone retort with the 
mixture, and for a receiver ufe an inverted retort con¬ 
taining water. Pelletier ufes a copper receiver made on 
the fame principle. The water in the receiver flops the 
phofphorus as it pafles over, and prevents it from coming 
in contadt with the air; and hereby a large quantity of 
phofphorus efcapes combuftion, becaufe it muft pafs 
through a column of water of near eight inches, before 
it has contaft with the air ; yet there is a fmall portion 
volatilized naturally, which is driven four inches above 
the neck, where this phofphorus burns in fparks, and 
the neck or tubulation is fometimes clogged up with pul¬ 
verulent phofphorus ; attention muft be paid to this, to 
prevent abfofption ; but, if the operation is condudted 
with {kill, this inconvenience does not take place. For 
the purification, &c. of phofphorus, fee the diredtions 
already given in page 200. At the beginning of the 
operation, hydrogen gas and carbonic acid are difen- 
• gaged, arifing from the decompofition of the water by 
the charcoal. When the phofphoric acid begins to be 
decompofed, the hydrogen gas dilfolves a little of the 
phofphorus, which gives it the property of finning in the 
dark by the contact of air. At lalt, if the heat is ftrong 
enough, the phofphorus takes the form of an oil, which 
falls into the water of the receiver, where it congeals. 
This experiment {hews, that at a high temperature, the 
carbon has more attradtion for the oxygen than thephof- 
phorus has ; that this has more r than the hydrogen, fince 
the water is decompofed before the phofphoric. acid ; 
laltly, that hydrogen can diflblve a certain quantity of 
phofphorus. It appears that the water of the receiver 
retains the phofphorated hydrogen; for, if expoled to 
the air in the dark, even after being {trained, it gives 
out a very bright phofphoric flame, eipecially if the fur- 
faces are renewed by agitation. 
The ufes of phofphat of lime are numerous. It ferves 
to polilli metals, jewels, and factitious (tones; to make 
cupels, or aflay-veffels > to take fpots of greafe out of 
S T R Y. 
fluffs, linen, or paper; in the manufacture of toys, before 
it is calcined; laftly, it is uled in the large manufac¬ 
tures of ammoniac, as carried on in the country of Liege. 
Phosphat of Posash.— This phofphat is but little 
known. It does not cryftallize; it becomes a fort of 
jelly when the folution is evaporated ; in that ftate it at¬ 
tracts the moifture of the air; it is decompofed by lime, 
barytes, and ftrontian, which have all more attraction 
for the phofphoric acid. Vauquelin has made fome expe¬ 
riments which feem to prove that loda takes this acid 
from potafh. This fait is not decompofable by charcoal, 
like the phofphat of ammoniac ; which muft be the cafe, 
fince carbonat of potafti is decompoled by the phofphure, 
which deprives the carbon, by a double affinity, of the 
oxygen it contains in combination with the potafti. It is 
not decompofed by heat, but vitrefies. Molt of the me¬ 
tallic folutions, as of filver, iron, mercury, and anti¬ 
mony, are decompofed by it. If the phofphat of potafti 
be not well faturated with alkali, it reddens blue vegeta¬ 
ble colours. 
Phosphat of Soda. —This fait is produced by a 
combination of phofphoric acid with fcda. It is very 
{oluble in water, and cryftallizes eafily, provided there 
be a flight excefs of alkali; and then it changes the fyrup 
of violets to a green. Its ufual form is a lengthened 
rhomboid, the faces inclining one over the other; fome¬ 
times it exhibits rhomboidal and prifmatic cryftals, or 
little lamellous cryftals ; but its cryftallization is generally 
a rhomboidal parellelopiped with blunt angles. If, inftead 
of having an excefs of alkali, it has an excefs of acid, it cry- 
llallizes very imperfectly, appearing as a mafs compofed 
of little flaming leaves like pearls, relembling fedative 
fait: this is what Bergman called Haupfs pearly fait. Its 
tafte is pleafant, fweet, but little faline. It is very 
tranfparent, but by expolure to the air loon grows white 
and opaque: the cryftals however preferve their form 
and much of their confidence, contrary to many {alts, 
which, when they lofe their water of cryftallization, be¬ 
come farinaceous. Phofphat of foda contains a good 
deal of this water of cryftallization, fo that it liquefies 
with a gentle heat; in a ftronger heat, it becomes opaque, 
and vitrifies, producing a glafs of the colour of milk. 
Under the blow-pipe, it begins to liquefy; then pafles 
into the white concrete ftate; and at laft a little vitreous 
globule, which appears tranfparent when melted: this 
little globule becomes opaque in cooling, and aflumes a 
polyhedral {hape. Phofphat of foda in this cafe adts the 
fame as phofphat of lead, according to Pelletier. As 
this fait melts eafily, it facilitates the fufion of earths, 
•either Ample or compound, as well as the metallic 
oxyds; hence mineralogifts and chemifts ufe it often 
with luccefs, in their experiments with the blow-pipe, 
to difcover the nature of the fubftances they are aflaying. 
This fait is decompofed by barytes, ftrontian, lime, 
and potafti, and by the calcarean, magnefian, barytic, 
and aluminous, falts; but the decompofition of the lat¬ 
ter is operated by double affinity. Molt of the metallic 
falts are decompofed by this; by which metallic phof- 
phats are very eafily and expeditioufiy formed, which 
indeed are fubjedt to vary in the proportions, becaule, 
in thefe decompofitions, the ftrongeft acid always takes 
the lead, and determines the relation between the weak¬ 
en acid and the bale which the other gives to it. This 
phofphat is often ufed in medicine for lulphat of foda, of 
which it has all the good properties: the dofe is one 
ounce in a large glafs of water. 
Phosphat of Ammoniac.— This fait is prepared 
by mixing carbonat of ammoniac and phofphoric acid to 
the point o~f faturation ; then evaporate with a gentle 
heat. It is difficult to obtain cryftals of this fait, for, if 
heated too much, the ammoniac volatilizes ; it is necef- 
fary, as the liquor evaporates, to add a little more am¬ 
moniac to replace that which flies oft in vapours; with¬ 
out this, the lalt would contain an excels of acid, 
Plioiphat of ammoniac is always found with phofphat 
of 
