PHO 
women weave a variety of fine matting for 
elotliing, and several otlier purposes. It 
is also manufactured in Norfolk Island for 
canvass and coarse linen clotlis. 
PHOSPHATES, in chemistry, salts 
formed of the phosphoric acid, with earths, 
alkalies, Ac. 'Hie alkaline phosphates are 
soluble and crystallizable ; they are also fu- 
sible, forming a kind of glass, and facilitate 
the fusion of a number of other substances. 
They may be decomposed in the humid 
way, by sulphuric and some other acids ; 
but in the dry way these decompositions do 
rot often happen. 'Hie phosphate of soda 
is much used in medicine ; it is purely sa- 
line, without any bitterness, which renders 
it a ^ood substitute for Epsom and Glau- 
ber’s salts. As it melts easily, and promotes 
the fusion of the earths and metallic oxides, 
it is used in chemical operations as a flux. 
Phosphate of ammonia exists in the urine ' 
of carnivorous animals, in considerable 
quantity, united with phosphate of soda, 
forming a triple salt, formerly denominated 
microcosmic, or fusible salt, in mine. 
PHOSPHITES, are salts formed of the 
phosphorous acid, with alkalies, earths, &c. 
In several of their properties they resemble 
the phosphates ; but maybe distinguished 
from them, by appearing luminous when 
heated with the blow-pipe, and by afford- 
ing, by distillatipn, a small quantity of 
phosphorus. 'Hiey detonate, too, with oxy- 
muriate of potash, and precipitate gold 
from its solution in a metallic state. By 
exposure to the air, they pass into phos- 
phates. 
PHOSPHORESCENCE, ? light. 
PHOSPHORI, S 
PHOSPHORIC add. When phospho- 
rus undergoes combustion in oxygen gas, a 
great quantity of white fumes are produced, 
which are deposited in white flakes. These 
are phosphoric acid; so that it is a com- 
pound of phosphorus and oxygen. The 
phosphoric acid was first shewn to be dis- 
tinct from all other acids, in the year 1743, 
by Margraaff. He found tliat it existed in 
the salts which were taken from human 
urine, and that phosphorus could only be 
obtained from this acid ; as well as that it 
could be converted into phosphoric acid. 
This acid was found to exist in some veget- 
able substances, although it was formerly 
supposed to be peculiar to animal matters. 
Phosphoric acid may be obtained not only 
by the method just mentioned, but also by 
transmitting a current of oxygen gas through 
phosphorus melted under water. 'I'he acid, 
PIIO 
as it is formed, combines witli the water, 
from which it may be obtained in a state of 
purity by evaporation. The specific gravity 
of this acid varies according to the different 
states in which it existsj In the liquid 
state it is 1.4; in the dry state it is 2.7; 
in the state of glass 2i85. It changes tlie 
colour of vegetable blues to red ; has no 
smell, but a very acid taste. When it is 
exposed to the air it attracts moisture, and 
is converted into a thick viscid fhiid like 
oil. It is very soluble in water. When in 
the form of dry flakes, it dissolves in a small 
quantity of this liquid, producing a hissing 
noise like that of a red-hot iron plunged 
into water, with the extrication of a great 
quantity of heat. The component parts of 
this acid have been accurately ascertained 
by Lavoisier, and it consists of, 
O.xygen..... 60 
Phosphorus 40 
100 
It combines with the alkalies, earths, and 
metallic oxides, and forms salts which are 
denominated phosphates. 
PHOSPHORITE, in mineralogy, is of 
a yellowish white, frequently spotted with 
grey : it occurs massive ; internally it is 
glistening, sometimes dull ; it is translucent 
on the edges, soft, brittle, and not very 
heavy. It forms a great bed in the pro- 
vince of Estremadura in Spain. In ap- 
pearance it resembles curved, lamellar, 
heavy-spar ; but it is harder and lighter 
than tills kind of heavy-spar. 
PHOSPHOROUS acid, is obtained by the 
slow combustion of phosphorus at the com- 
mon temperature of the air. If phosphorus, 
in .small pieces, be exposed to the air in a 
glass funnel placed in a bottle, it attracts 
the oxygen and moisture from the atmos- 
phere, and runs down into the bottle. This 
is the phosphorous* acid. By this process, 
about three times the w eight of the phos- 
phorus is obtained. It is then in the form 
of a white thick liquid, adheiing to the sides 
of the vessel. It varies in consistence ac- 
cording to the state of the air. Its specific 
gravity is not known. It has an acid pun- 
gent ta,ste, not difterent from phosphoric 
acid. It also reddens vegetable blue co- 
lours. 'Hie phosphorous acid is not altered 
by light. When exposed to heat in a retort, 
part of the water combined with it is first 
driven off, and when it is concentiated, 
bubbles of air suddenly rise to the surface, 
and collect in the form of white smoke, and 
