334 
CHEMISTRY'. 
often compounded of hydrogen and Carbon. 
The bases of the alkaline salts aie often not 
more simple than those of the acid; , .... 
has been proved with respect to ammonia, 
.vhich is composed of hydrogen and azote. 
bee Ammonia. 
It results from our knowledge of thegases 
(see Air, pages 28 to 3.5) that there are a cer- 
tain number of substances which vve may con- 
sider as simple bodies, whether they are so or 
not, because no means have yet been disco- 
vered by which they may be decomposed. 
The substances of this kind are, 
f -Light 
Simple substances, which j Q^vgen 
may be considered as the y - ^ 
-elements of bodies. 
I Hydrogen 
f Carbon 
Simple non-metallic sub- j pi'^n\Tnrii<? 
stances, oxidable amH Muriatic radical 
acidiiiable. Fluoric radical 
v Boracic radical 
) Azote or nitro- 
gen 
Simple, earthy, salifiable 
substances. 
' Lime 
Magnesia 
Barytes 
i Alumina 
Silica 
Strontiaa 
Zirconia 
Glucina 
Yttria 
( Platina 
... . , 1 Gold 
-Simple metallic substances J yp ver 
oxidable. f Mercury 
1 Copper 
l Iron 
'Lead 
Tin 
Zinc 
Antimony 
Bismuth 
Cobalt 
Nickel 
Manganese 
Vegetables are not only indebted to light 
for their colour, their taste and odour are de- 
rived from the same source. From this 
cause it happens that hot climates are the 
native countries of perfumes, odoriferous 
fruits, and aromatic resins. The action of 
light on the organs of vegetables causes them 
to pour out streams of pure air from the sur- 
faces of their leaves, while exposed to the 
sun: whereas, on the contrary, when in the 
shade, they' emit air of a noxious quality. 
Even animals, in general, droop when de- 
prived of light; and it appears .to be of great 
importance to the health and happiness ot 
human beings. 
All metallic oxvdes,but especially those of 
mercury, bismuth, lead, silver, and gold, 
become of a deeper colour by exposure to 
the sun ; some of them become perfectly re- 
vived, others only partially. Many bodies, 
if exposed to light, either at high or low tem- 
peratures, combine w ith it, and emit it again 
under certain circumstances. 1 hese are call- 
ed solar phosphori. Substances ot this kind 
The combination 
Oxygen forms 
Azote or nitrogen 
Oxygen and azote 
Oxygen and carbon ^ 
Oxygen and the muriatic radical — 
-Oxygen and the muriatic radical, sur- > 
•charged with oxygen Jt 
Oxygen and sulphur 
Oxygen and the fluoric radical — 
Ammonia 
Hydrogen 
Hydrogen and sulphur 
Hydrogen and phosphorus 
Hydrogen and carbon 
Water *” 
have been prepared by various chemists ; I 
the principal of which are, the phosphorus of I 
Canton, Baldwin, Homberg, and the Folog-j 
nian phosphorus. I hese have the propel ty I 
of shininu in the dark. Various animal and! 
'•‘•'Stable substances seem to possess this | 
"Simple metaUlc'Substances i 
oxidable, and some ot-f-Lranium 
-them acidiflable. Titanium 
Tellurium 
Columbimn 
Tantalium 
Chrome 
Arsenic 
Molybdena 
^Tungsten. 
These simple substances may be combined 
with each other, and with other substances, 
in order to form compounds. 
Of fight. The physical properties of light 
.will be considered under Optics. 1 Ins sub- 
stance seems to have considerable lnlluence 
upon many chemical processes. The effect ot 
Wit unon- vegetation is well known. Many 
flowers follow the course of the sun, and 
plants tliat grow in houses, seem soucitous, as 
it were, -to get at the light. Plants that grow 
in the shade, or in darkness, aie pale, and 
without colour: and when this is the case, 
they are said to be etiolated or blanched. 
Gardeners avail themselves of this tact to 
render vegetables white and tenc.cn-. I he 
more plants are exposed to the light, th 
more colour they acquire. 5 et the dead 
vegetable is deprived of coiour by exposuic 
fo it. 
Of oxygen. Oxygen is a substance diffus- 
ed in great abundance throughout nature ; it 
forms nearly a third in weight of our atmo- 
sphere. Animals absorb a great quantity of 
it by respiration; and it combines with other 
bodies to convert them into oxides and acids. 
A certain number of conditions must be 
united, in order that a body may be oxyge- 
nated. The first is, that the constituent par- 
ticles of this body must not exercise between 
themselves an attraction stronger th n that 
which they exercise on oxygen. Il they do 
not possess this superior force of attraction 
for oxygen, it may be communicated to them 
artificially, by exposing them to heat, that is 
to say, by introducing into them caloric, 
which, separating them from each other, di- 
minishes the force of their reciprocal attrac- 
tion, and allows them to exercise a more 
powerful one on the oxygen: oxygenation 
will then take place. The degree ot heat 
necessary to produce this phenomenon is 
not the same for all substances: some may be 
oxygenated at a temperature so low that we 
never find them but in an oxygenated state. 
Of this kind is the muriatic radical, which 
never presents itselt to us simply, but always 
in an acid, which it has been hitherto im- 
possible to decompose. To oxygenate the 
greater part of bodies, and almost all simple 
substances, in general, it will be sufficient to 
expose them to the action of the atmo- 
spheric air, and to raise them to the proper 
temperature. The temperature necessary 
to oxygenate lead, mercury, and tin, is not 
greater than that in which we live; but, on 
phosphorus, 1 he glow-worm is a lemaikable I 
instance. Dead fish, rotten sea weeds, ai.cl I 
great numbers of insects, have this prope»ty| 
in a great degree. 
Instruments for measuring the degree orl 
intensity of light are called photonieteis. 
Of caloric. All the bodies in nature areiirwl 
mersedin caloric, which penetrates then pai is| 
throughout, and which nils up the inteivais 
left between the particles. In some cases the 
caloric is fixed in these bodies, and in such a 
manner as even to contribute to tneir solidity j 
but it often separates their particles also, try 
exercising on them a repulsive force ; and it 
is on its greater or less action oi accumulation 
that the transition of bodies from the solic 
state to the liquid, and from the liquid to tut 
aeriform, depends. 
of caloric with 
Oxygen gas, or vital air 
Azotic gas, or mephitic air 
Nitrous gas * 
Carbonic acid gas, and gas oxide of carbonj 
Muriatic acid gas 
Oxymuriatic acid gas 
Sulphurous acid gas 
Fluoric acid gas 
Ammoniacal gas 
Hydrogen gas 
Sulphurated hydrogen gas 
Phosphorized hydrogen gas 
Carbonated hydrogen gas 
Aqueous gas, and so of all other evapoiab 
liquids. 
the other hand, a pretty high degree of he 
is necessary to oxygenate iron and cpppjl 
in the dry way, and when the oxygen is n 
assisted by the action of humidity. Sum 
times the oxygenation takes place with gr| 
rapidity, and in that case is aocompalrfl 
with fleat, light, and even flame : such is t! 
combustion of phosphorus in the air, an <9 
oxygen gas. r I flat of sulphiu is much 9 
rapid. Such also is the combustion of ir 
in pure oxygen gas. Example : If a pi€ 
of iron wire bent in a spiral shape, as A (J 
20.), is hung in a receiver B fillet-' with! 
yaen gas, and by means ot a small piece 
phosphorus, it is inflamed, the metal « 
burn with the greatest briiiiancv . I in, leL 
and the greater part of the metals, oxidi 
slowly, and without the disengagement of tj 
caloric being sensible. 
There is still another method of oxygen I 
ing simple substances. Instead of exposjj 
them to oxygen united with caloric, J 
oxygen ma\ be presented to them in uni 
with some metal for which it has little afiil 
tv. The red oxide of mercury is one! 
those best fitted for accomplishing this! 
iect, because the oxygen in that state J 
heres very little to the metal: it is disengad 
from it at that degree of heat at which gl 
begins to become red. 'I he black oxide 
manganese, the red oxide of lead, the o . vi (9 
silver, and almost all the metallic oxides, c 
in a certain degree, .produce the same effl 
Every metallic reduction or reviviftcatil 
is an oxygenation of charcoal or sojj 
other combustible matter by a meti| 
