O X I 
20 
lime. Tf any is present, a white powder im- 
mediately precipitates. The reason of this 
is, that oxaiat of lime is altogether insoluble, 
and oxalic acid in consequence is capable of 
taking lime from every other acid. 
OXALIS, ZL’oorfsorre!, a genus of the pen- 
tagvnia order, in the decandria class of plants, 
and in the natural method ranking under the 
1 4th order, gruinales. The calyx is penta- 
phyllous, the petals connected at the heels, 
the capsule pentagonal, and opening at the 
angles. There are 9b species; of which the 
common woodsorrel grows naturally in moist 
shady woods, and at the^ sides of hedges, in 
many parts of Britain, and is but seldom ad- 
mitted into gardens. The roots are com- 
posed of many scaly joints, which propagate 
in great plenty. The leaves arise immedi- 
ately from the roots upon single long foot- 
stalks, and are composed of three heart- 
shaped lobes. They are gratefully acid, and 
of use in the scurvy and other putrid disor- 
ders. The bulbous kinds from the Cape are 
elegant ornaments of the greenhouse. 
OXIDE, any substance combined with 
oxygen, in a proportion not sufficient to pro- 
•duce acidity. 
Oxygen is capable of combining with bo- 
dies usually in various proportions, consti- 
tuting a variety of compounds with almost 
every substance with which it is capable of 
uniting. Now the whole of the compounds 
into which oxygen enters, may be divided 
into two sets: 1. Those which possess the 
properties of acids ; and, 2. Those which 
are destitute of these properties. The first 
set of compounds are distinguished by the 
term acids ; to the second, the term oxide 
has been appropriated. By oxide, then, is 
meant a substance composed of oxygen and 
some other body, and destitute of the pro- 
perties which belong to acids. It is by no 
means uncommon to find a compound of the 
same base and oxy gen belonging to both of 
these sets, according to the proportion of 
oxygen which enters into the compound. In 
al| "these cases, the smaller proportion of oxy- 
gen constitutes the oxide ; the larger the 
acid. Hence it follows, that oxides always 
contain less oxygen than acids with the same 
base. 
Oxygen combines with three distinct set of 
bodies, the simple combustibles, the incom- 
bustibles, and the metals, and forms oxides 
with every individual belonging to these sets. 
These oxides vary as the substance which con- 
stitutes the base ; but all the oxides of the 
simple combustibles are combustible, except 
the oxide of hydrogen, which is a product of 
combustion; all the oxides of the simple in- 
combustibles are supporters of combustion ; 
and all the oxides of the metals are either 
products of combustion or supporters. Of 
course, the first set of oxides (except that of 
hydrogen) cannot be formed by combustion ; 
neither can the second set ; but part of the 
third set are formed by combustion, a part 
by the union of the oxygen of supporters 
without combustion. 
Besides these oxides, which may be con- 
sidered as simple, because they contain but 
one ingredient combined with oxygen, there 
is another set much more numerous than 
they, consisting of oxygen united at once 
with two or more simple substances. These 
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bodies may be distinguished from the others 
by giving {hem the name of compound ox- 
ides. 
Oxides are often distinguished according 
to the degree of oxygen they contain. Thus 
the protoxide or first oxide denotes a metal 
combined with the least portion of oxygen ; 
deutoxide, or second oxide, a metal com- 
bined with two doses of oxygen; and when a 
metal has combined with as much oxygen as 
possible, the compound is called a peroxide. 
Oxide, carbonic. When a mixture of 
purified charcoal and oxide of iron or zinc 
is exposed to a strong heat in an iron retort, 
the metallic oxide is gradually reduced, and 
during the reduction a great quantity of gas 
is evolved. This gas is a mixture of carbo- 
nic acid gas, and another which burns with a 
blue flame. This last is. carbonic oxide. 
OXYBAPHIJS, a genus of plants as yet 
unclassed, nearly allied to the mirabilis, a 
native of Peru. 
OXYGEN, in chemistry, a simple sub- 
stance that enters into the composition of 
water and air. The term oxygen signifies 
that which generates or produces acids. This, 
one of the most characteristic properties of 
this body, was discovered by l)r. Priestley 
in 1774. It was at first called dephlogisti- 
cated air, and afterwards successively known 
by the names of eminently-respirable air, 
pure air, vital air, as long as it was not known 
that this aerial form is merely one of its states 
of combination ; which, notwithstanding its 
frequency, and its being less impure in this 
than in any other condition, does not prevent 
its being concealed in other states; and more 
particularly as, by combining with many bo- 
dies, it loses this elastic state or appearance 
of air. As soon as this truth was well proved, 
and clearly explained by Lavoisier, the ne- 
cessity was admitted of giving it a different 
name, which might be applicable to all the 
states in which it could exi>t, as well that of 
gas as of the liquid or solid form. Lavoisier 
first called it {he oxygenous principle; and 
the French school having decided for the 
word oxygen, by admitting a simple change 
of termination in the first word proposed 
by Lavoisier, this name became generally 
adopted. 
The effect of oxygen is of such import- 
ance, that its presence must be stated as the 
most indispensable condition of combustion ; 
which would not otherwise take place. It 
truly constitutes the essential part of that 
process, because its most decided and exten- 
sive character is its indispensability in that 
process. 
Oxygen, like many other natural bodies, is 
found in three states, but in neither of them 
is it alone or insulated. In the gaseous form 
it is dissolved in caloric; in the liquid and 
solid form it is combined with different sub- 
stances, and can never exist concrete and 
pure without combination, like many other 
substances no less decomposable than itself. 
And though we can, in imagination, conceive 
it alone, insulated, pure, and in a solid state, 
experiment has never yet exhibited this fact, 
it is a discovery which still remains concealed 
in the bosom of nature ; or may exist, ill un- 
derstood, under the name of some substance 
yet unknown in our collections of minerals. 
As oxygen is frequently contained in a 
more or less solid form in several natural 
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fossils which have undergone combustion, 
anil as it has much attraction for caloric, it 
is only required that some one of those fos- 
sils should be heated more or less, or pene- 
trated with a great quantity of caloric, in or- 
der to disengage this principle, and obtain" it 
in the form of a ; r or gas. 1 his is done by 
chemists to procure oxygen gas. '1 hey ex- 
pose certain substances, particularly metals 
burned by nature or by art, to a lire of con- 
siderable activity in -closed vessels, so dis- 
posed as to conduct and receive, under in- 
verted jars, the elastic fluid intended to be 
collected. The burned matter passes again 
to a combustible state ; and the ox\ gen w hie h 
gave it the burned state, being separated and 
fused by caloric, for which it lias a great at- 
traction, becomes developed in the form of 
gas. It is the product of a true combustion. 
Of the two bodies which form oxygen gas, 
the caloric, which is the solvent, and gives it 
the state of invisibility and elastic fluid, not 
being ponderable; the solidiliable base which 
is dissolved, or oxygen, being the only pon- 
derable and fixable body in all the substances 
with which this gas can combine ; and che- 
mists having no other means of obtaining 
oxygen in a simpler state than that of gas, 
in which they use it for a great number of 
operations or combinations ; many of them 
are habituated to denote this gas by the 
simple name of oxygen. This is, neverthe- 
less, an error of nomenclature, and inimical 
to the perspicuity of chemical doctrine ; be- 
cause the word oxygen ought only to be used 
to denote the base of this gas considered 
alone, or in all tjie possible states, but par- 
cularly in the numerous combinations wherein 
jt possesses the liquid or solid state. 
Oxygen gas. See Air. 
OXYMEL, in pharmacy, a composition 
of vinegar and honey. 
OXYMURIATIC ACID. This acid was 
discovered by Scheele in 1774, during his 
experiments on manganese. He gave it the 
name of dephlogisticated muriatic acid, from 
the supposition that it is muriatic acid de- 
prived of phlogiston. The French chemists, 
after its composition had been ascertained, 
called it oxygenated muriatic acid; which 
unwieldy appellation K invan has happily 
contracted into oxymuriatic acid. 
It may be procured by the following pro- 
cess: Put into a tubulated retort a mixture 
of three parts of common salt, and one pait 
of the black oxide of manganese in powder. 
Place the retort in the sand-bath of a furnace, 
plunge its beak into a small water-trough, 
and lute a bent funnel into its mouth. When 
the mixture has acquired a moderate heat, 
pour into it at intervals through the bent 
funnel two parts of sulphuric acid, which 
ought to be somewhat diluted with water. 
An effervescence ensues ; a yellow-coloured 
gas issues from the retort, which may be re- 
ceived in large phials fitted with ground stop- 
pers. 
Oxymuriatic acid gas is of a yellowish- 
green colour, its odour is intolerably acrid 
and suffocating. It cannot be breathed with- 
out proving fatal. The death ot the inge- 
nious and industrious Pelletier, whose chemi- 
cal labours have been so useful to the world, 
was occasioned by his attempting to respire 
it. A consumption was the consequence of 
this attempt, which, iu a short time, proved 
