O X Y 
107 
O X Y 
fraftures, and to form callufes; compofed chiefly of faf- 
fron, with gums difi'olved in vinegar. 
OX'YD, or Oxide, f. The term ufed in chemiftry, to 
denote a very numerous clafs of bodies formed by the 
union of certain bafes with a fmaller proportion of oxy¬ 
gen than what is neceflary for their converfion into acids. 
The molt remarkable of thefe bodies are what were 1 for¬ 
merly called metallic calces, and have for their bafe lb me 
metallic fubftance. It is in this Hate that metals are often 
contained in the ores, from which they are extrafted, and 
converted into the metallic form, by theprocefs called re¬ 
duction. Metals are converted into oxyds by combuftion, 
and-by folution in acids; and many of them aflurae this 
form from the aftion of the atmofphere alone, but more 
readily when this is affifted by moifture. See the article 
Chemistry, vol. iv. p. 165. and Mineralogy, vol. xv. 
p. 478. 
OXYDA'TION, or Oxidation, f. The procefs by 
which bodies are converted into oxyds. 
OXYDER'CIA, J'. [from the Gr. fharp, and 
to fee.] Medicines to help the light. 
OXYDRA'C^E, in ancient geography, a people of 
India, who inhabited the diftrift now called Outch, near 
the confluence of the Acelines (Chunaub) with the Indus. 
OXYGA'LA, f [from the Gr, 0|v;, fharp, four, and 
yx'Ka,, milk.] Sour milk. The Turks ufe this as a popu¬ 
lar drink, and call it igur. Vigenere fays, they drink 
four milk diluted with water; which is found to cool and 
nourifli better than the milk alone. 
OXYGA'RUM, f. A word ufed by the ancients to ex- 
prefs a mixture of vinegar and garum, which is a pickle 
for preferving fifli, or a fimple mixture of fea-falt and 
water. 
OX'YGEN, f. [Greek.] A principle exifting in the air, 
of which it forms the refpirable part, and which is alfo 
neceflary to combuftion.— Oxygen , by combining with 
bodies, makes them acid; whence its name, fignifying 
“ generator of acids.” Todd. 
It appears, by M. Klaproth’s extracts from a Chinefe 
book written in the year of our era 756, that the Chinefe 
had fome faint notions of oxygen. They called it “ the 
impure part” of air; and faid that it combined with ful- 
phur, charcoal, and metals ; that it may be extracted from 
laltpetre by means of heat, and from the black ftone called 
he-tann-cliL They feem to have thought likewife that it 
was a conftituent of water. 
Oxygen Gas is the dephlogi/licated air of Dr. Prieftley, 
the firft difeoverer of it 5 the vital air of others. Under the 
article Chemistry, vol. iv. p. 193,4. we have given the 
various procefles for obtaining it in a pure ftate. In this 
ftate it exhibits the following charafteriftic properties. 
It is permanently elaftic at all known temperatures; co- 
lourlefs, tranfparent, and without finell and tafte. It is 
refpirable, and may be breathed for fome time without in¬ 
convenience. Its fpecific gravity, compared to atmo- 
fplieric air, is as 111 x to 1000; to hydrogen as 15 to 1. At 
a mean temperature and preflure, 100 cubic inches weigh 
33*888 grains. 
This important element is very generally diffufed 
throughout nature. It exifts in the atmofphere, and in 
water; it is often found in combination with metallic 
bafes, and it conftit;utes one of the ultimate principles of 
almoft all animal and vegetable matter. It is eflential to 
the refpiration of animals, and is frequently abforbed by 
plants, contributing to the healthy performance of fome 
of their mod intricate funftions. Dr. Davy (Left, at the 
Royal Inftitution, Mar. 7, 1812.) has demonftrated, that 
oxygen-gas forms one-fifth of the air of the atmofphere, 
and is the principle neceflary for combuftion and refpira¬ 
tion. In its pure form it produces a number of brilliant 
refults, by afting upon inflammable bodies; the metals 
burn in it brilliantly and abforb it, and it is a conftituent 
part of moft acids and alkalies. 1 STr. Davy ftiowed a beau¬ 
tiful experiment, in which the fame oxygen, by being 
combined with fulphur, formed an acid, and, by being ab- 
ftrafted from the fulphur by potaflium, which took place 
with vivid combuftion, formed an alkali. Mr. Davy en¬ 
tered into fome general views refpefting the manner in 
which the oxygen of the atmofphere, and that diflolved 
in waters, were renovated. Oxygen is abforbed, and car¬ 
bonic acid is produced, in the refpirations of animals, in 
combuftion and in fermentation; vegetables, in the fun- 
ftiine, ablorb carbonic acid, and evolve oxygen. Mr. Davy 
combated the idea that this funftion of vegetable life was 
not fufficient to fupply oxygen equivalent to that con- 
fumed. Therdis no other mode known in which carbonic 
acid is decompofed in the procefles of nature; and, did not 
vegetables abforb it, it mutt be conttantly accumulating, 
which is known not to be the cafe. A great part of the 
folid furface of the globe is covered with plants, and light 
is eflential to their healthy growth, and therefore great 
quantities of oxygen are produced in countries where 
there is little animal life. Fillies, he Hated, will live in 
confined portions of water containing aquatic plants; and 
the oxygen they abforb is compenfated for by the plants, 
which decompofe the carbonic acid afforded in their ref¬ 
piration. This view of the connection of plants and ani¬ 
mals in their aftion upon air, is not only fupported by 
many proofs, but is likewife, fays Mr. Davy, conformable 
to the analogy of nature; it proves to us that the meaneft 
weed, the moft poifonous plant, is not without its ufes in 
the economy of things. The different parts of the at¬ 
mofphere are mingled by winds; the carbonic acid not 
confumed by found plants is carried into the waters, dif- 
folved by rain, miffs, and dews ; the fea is kept in agita¬ 
tion by waves and tides, and its influence upon the air 
conftantly exerted ; the ftorm and the whirlwind aflilt in 
this beneficent miniftration ; and the harmony difplayed 
in fuch diverfified combinations, offer a ftriking inltance 
of the wifdom and perfection of the arrangements con¬ 
nected with the prefervation of life in the iyftem of the 
globe. 
It will create no furprife, therefore, in our readers, 
when they are told that the inhalation of this gas, em¬ 
phatically called vital air, has been recommended in cafes 
of catalepfy, epilepfy, and confumption. Many cures 
have been effefted by it within our own knowledge ; but 
it may become a dangerous engine in the hands of un- 
fkilful perfons : it is a remedy not to be trifled with. 
Mr. Thenard has recently been able to combine oxygen 
with acids to an almoft-unlimited extent, chiefly by means 
of the peroxyd of barium. His general method was, to 
diflolve the peroxyd in the acid intended to be oxyge¬ 
nized, and afterwards to feparate the barytes by means 
of fulphuric acid ; the oxygen was thus transferred from 
the peroxyd of barium to the acid ; and, by repeating the 
operation, he found that additional doles could be added. 
In this way he oxygenized the nitric, muriatic, phofphoric, 
and other, acids ; and, by taking advantage of its other 
properties, the muriatic acid in particular, was oxygenized 
even fo far as to contain 64 atoms of oxygen to 1 of mu¬ 
riatic acid. Thefe oxygenized acids combine with the 
different bafes, and neutralize them; but they are by no 
means permanent, giving off their fuperfluous oxygen by 
the application of heat, &c. By fimilar methods M. The¬ 
nard has been able to combine additional doles of oxygen 
with many of the metallic oxyds. Annales de Ckimie , 
tome ix. 
OXYG'ENATED MURIAT'IC AC'ID, or Oxymu- 
riatic Acid. See the article Chemistry, vol. iv. p. 218. 
It is now called Chlorine, (from Gr. green,) in 
confequence of fome new properties dilcovered in it, and 
the abfence of others it was fuppofed to poflefs. 
Sir Humphry Davy, in his Chemical Leitures at the 
Royal Inftitution, divides all fubltances not yet decom¬ 
pounded, into two great clafles; fupporters of combui- 
tion, and combuftible bodies; and, in the firft clafs, he 
fays, there are only two fubftances as yet known ; oxygen, 
and chlorine, hitherto called oxymuriatic acid 
Sir H. Davy’s new theory is the following: That oxy- 
3 muriatic 
