C H E M 
nitrat, fince that fait does not produce the fame pheno¬ 
mena with combuftible bodies treated in the lame man¬ 
ner. Bertholiet, who firft diicovered the facility with 
which this fall gives out its oxygen to combuftible bo¬ 
dies, has made leveral attempts to form a gun-powder 
fl'ronger than that commonly ufed. His expectations 
w'ere readied; but he found that the life of it would 
become extremely dangerous, from its extraordinary in¬ 
flammability. 
Of PHOSPHATS. 
Phofphoric acid unites to earths and alkalis, and forms 
falts, which have obtained the name o i phofphats \ while 
thofe which refult from the combinations of the. phol- 
phoious ajid, are called pliofphits ; which denominations 
indicate at once the nature of the fait, of the bale, of the 
acid, and of the ftate it is in. The combinations of phof- 
phone acid with earths, alkalis, and fome metallic oxyds, 
are decompoled by the fulphuric, nitric, muriatic, oxa¬ 
lic, &c. acids, when made cold, and in water; but it is the 
contrary with heat, and the fulphat of potalh, nitrat of 
potalli, "&c. are decompofed by that dcid. 
Phosphat of Barytes. —This may be made two 
ways, either by diredtly uniting, to Saturation, pure ba¬ 
rytes with phoiplioric acid, or combined with phofphoric 
acid; or elfe by double affinity, by bringing in conta6l 
a barytic fait difiolved in water, fucli as the muiiat or 
nitrat, with phofphoric acid combined with an alkali, 
whether foda, potalh, or ammoniac : then the phoiplioric 
acid attacks the barytes, and forms a depefit in the li¬ 
quor, while the other fait remains in loliition. 
This lalt melts by fire without changing its nature, 
and vitrifies in a red heat of leveral hours. It melts un¬ 
der the blow-pipe; and, if the operation be performed 
on a bit of charcoal, it ipreads a yellow phofphoric flame ; 
the globules it forms become opaque in cooling, unlels 
they contain an excels of alkali. It is infoluble in wa¬ 
ter ; but becomes loluble by an excels of acid. It is not 
decompoled by earths and alkalis; neither do acids en¬ 
tirely decompole it, with the exception, as is luppol’ed, 
of the fulphuric acid; but, as pholphat of barytes has a 
very great affinity for an excels of acid, the nitric and 
muriatic acid only take away a part of the barytes, and 
an acid pholphat of barytes remains. 
Phofphat of barytes is decompoled by thofe falts which 
a£l by double affinity, elpecialiy when the acid of thole 
falts afts more ftrongly upon the barytes than upon their 
bales; thus pholphat of barytes is decompofed by fulphat 
of barytes and by all the alkaline carbonats, whether 
hot or cold ; but, in the former cale, the carbonat of am¬ 
moniac is not iufficient. This fait has not hitherto been 
applied to any ule; but it might be employed, to advan¬ 
tage, for feparating the fulphat of lime from the phof¬ 
phoric acid drawn rrom bones: by boiling thefe things 
together, the fulphuric acid unites to the barytes, and 
the lime to the phoiplioric acid ; whence arile two perfedt- 
ly-infoluble lalts. 
Phosphat of Strontian. —This fait is prepared by 
combining phoiphoric acid with pure ltrontian, in the 
proportion of 58-76 of ltrontian, and 41*24. of phofphoric 
acid. Heated with the blow-pipe, it melts into a white 
enamel, and fpreads a phoiphoric light. It is foluble in 
water, by the aid of the muriatic and nitric acids. It is 
decompofed by barytes, and by the fulphuric acid, be¬ 
coming acidulated phofphat. 
Phosphat of Lime. —This fait exifts abundantly in 
nature, and in confnierable mailes : it conftitutes the 
bale of the Ikeletons of moll animals; and it is found 
more oriels in the allies of all vegetables. In Spain, in 
the province Eltramadura, it has been lately diicovered 
in large and extenfive ftrata : it is of an opaque colour, 
flattered with yellowiih fpots aiding from the oxyd 
of iron. 
The phofphat of lime, ufed :n chemiftry ?md the arts, 
is drawn from the bones of animals,' ftrongly calcined in 
I S T R Y. 251 
furnaces, to feparate the animal fubftances which con- 
ne£l the parts This lalt b) exposure to heat, feems to 
be only loftened to aflume a kind of iemi-fufion, like 
porcelain earth; therefore thefe matters, when ftrongly 
calcined, have been called porcelaincd bones. Yet bones, 
expofed to a very ftrong heat, throw out a yell w phof¬ 
phoric light, which indicates a decompcfiti 11 of phof¬ 
phoric acid, whole pholphorus burns at a cert; in dif- 
tance ; but this decompofition is very confined, and foon 
flops. Perhaps thele phenomena may arile from a fmall 
quantity of pholphat of ammoniac, contained between 
the bony plates, or in the membranes which unite them. 
Pholphat of lime is infoluble in water, but becomes 
foluble with the help of an acid, fucli as vinegar, or the 
phofphoric acid itfelf. Alkalis and earths produce no 
alteration in it, whence it is evident that its principles 
are very ftrongly united ; but the fulphuric, nitric, mu¬ 
riatic, acetous, and oxalic, acids, decompofeit in part, juft 
to the point from-which they had feparated from the phoi¬ 
phoric acid, about 0-40 of the lime contained in a cer¬ 
tain mals of the calcareous phofphat. It is by the de¬ 
compofition of pholphat of lime with nitric acid, that 
Scheele lias explained the nature of bones : but the lame 
end is now obtained in a more fimple way, as follows : 
Calcination of Bones .— A furnace is to be built of brick, 
about eight inches high, and forty inches wide; lay bars 
of iron acrofs, to form a kind of grate, and upon this 
place the bones to be calcined ; leave a hole about eight 
inches- fquare in the furnace, to lupply a current of air; 
and through this hole introduce fome pieces of wood al¬ 
ready lighted, which will let lire 10 the bones : then they 
burn of themlelves till they are 'Sufficiently calcined. 
This operation, which is attended with no expence, 
Ihould be made in the open air, becaufe the oily matter, 
which comes over by combuftion, is ltill fufficient to be 
dangerous in a fmall ^confined place. Thefe bones are 
then reduced to fine powder, and lifted. 
The next operation is the reparation of the phofphoric 
acid by means of fulphuric acid. Take one part of thefe 
Calcined bones, temper them in four parts of water, and 
pour over the mixture one half part .of concentrated ful¬ 
phuric acid, fliiring the mixture continually. Let the 
whole macerate for four-and-twenty hours, birring it 
from time to time, to renew theTurfaces and points of 
contaft. At the moment the acid is poured on, there 
is a dilengagement of caloric, and a bii 11c effervefcence, 
occafioned by the dilengagement of carbonic acid ; for, 
befides the phofphat of lime, the bones contain ajfo a 
certain portion of carbonat of lime. The fulphuric acid 
now unites with the lime, forming an infoluble lalt; and 
the phofphoric acid, being let at liberty, difiolves in the 
water. The acid which is obtained Hill contains a good 
deal of lime, and, is to be confidered, according to the 
experiments of Fourcroy and Vauquelin, as an acidulat¬ 
ed phofphat of lime. To feparate all the phofphoric acid 
from the bones, the acidulated phofphat may be decom¬ 
posed by oxalic acid, carbonat of ammoniac, or nitrat of 
lead : but the firft is too expenfive ; the lecond, by pie- 
cipitating all the lime as chalk, and forming a phofphat 
of ammoniac, decompofable indeed by charcoal, gives the 
required refult, but it rather confines the operation by 
furnifhing carbonat of ammoniac; the third (nitrat of 
lead) leems preferable, becaufe it forms nitrat of lime 
which is held in lolution, and pholphat of lead which is 
precipitated, in the liquor: this precipitate well wulhed, 
and heated with very dry charcoal, eafily parts with all 
its pholphorus. 
From the experiments of the above-cited chem’ifts, it 
appears, that 100 parts of neutral phoiphat of lime, or 
earth of calcined bones, contain 0-41 of phoiphoric acid, 
which, according to the analysis of Luvoifkr, contain 
0-16 of pholphorus; thus, by letting thele 0-41 of phof¬ 
phoric acid at liberty, there is gained by diftiijation with 
charcoal, 0*16 of pholphorus, or iittie lets than a fixth 
part of the weight of the earth, which in truth contains 
that 
