Staunton spectator, and general advertiser. [volume] (Staunton, Va.) 183?-1849, 1846-01-01
A g lg I q w u II U 1g 20
FROM rul LEXINGTON GAZETTE.
Notes Of course Of Lectures on Agricultural Chem
istry delivered before an Association of Praeti-
cal Farmers.
BY GEORGE d. ARMSTRONG,
PnorEsson OF CHEM,srnY IN wAsHINoroN COLLEGE,
= LExiSo TON, VA.
LECTURE Nv.


ton was then directed to two of these, viz: Oxy-
gen and Chlorine. To-day, we will examine in
to the properties OF Hydrogen, an important COM
pound which hydrogen forms with oxygen, viz:
| IPater, and the phenomena of CAPILLARY .qifrac-
lion And allow me here 10 remind you that
| our examination OF these subjects, must, for the
pPresen', be such as belongs rather 10 general
than TO agricultural chemistry, for the reason that
where several elements enter into the composition
OF any substance, or are jointly concerned in the
production OF any effect, and such is the case
with the chemical operation of vegetable and ami
NAL lite, some general knowledge of each Of
these elements is necessary to explain fully the
operation OF any one of them. We must there
| tore complete our general examination of these
elements before we can enter upon the consdera-
ton OF subjects belonging TO Agricultural Chem
istry proper.
Hydrogen, when separated from combination
with other elements, mall ordinary circumstances.
exists In the form of gas, and hitherto, chem
lists have failed In all their efforts through the
agency OF great pressure or an intense degree of
cold, to make II assume either the liquid or solid
form. In combination with other elements it ex-
ISIS as gas, In carburetted hydrogen (the gas
used for purposes of illumination in our cilies,)
as liquid In water, and as solid, in many We
geta6ie and animal products, such as sugar,
starch, DC. Hydrogen is not very abundant
element in the mineral kingdoms il is far more
abundant In the other departments Of nature, few
|
animal life being destitute of it. Like oxygen,
u is destitute OF color, odour and TASTE SO that
by The unaided senses we cannot distinguish it
from common atmospheric air:-like that of gas
1t Is also sparingly soluble in water; 100 cubic
inches of that liquid absorbing only about /. of
the gas. Hydrogen is the linhtest among the
gases, and of course the lightest substance known
being nearly is times lighter than common air,
about 10000 times lighter than water and about
100000 times lighter than platinum. Ii is in
consequence OF its extreme lightness that this
gas is used in filling balloons.
Among its more important chemical propertics
are the following, viz
LIST. Although not possessed Of so wide range
oil chemical affinity as Oxygen, it is nevertheless
capable OF chemical union with many other ele-
ments, often forming with them very important
compounds, such as water, sugar. alcohol, &c.
Snd. IL is incapable OF supporting either ami
mai or vegetable life, although mixed atmos.
phere OF oxygen and hydrogen may be brcaihed
without Inconvenience. Ii is also incapable of
supporting combustion "a lighted taper plunged
into This gas, is immediately cxtnguished.
3fd. AZ ydroSon 40 i.s.lf urniIIelIiy cumbusIi- !
BILE; as exempfed in the experiment lust refer
red to ;-whilsi the lighted taper plunged into !
this gas is immediately eXtngushed, the gas it, |
sell Is kIndled and burns with {. yellowish blue |
hame at the mouth of the vessel, the point at
winch 1t meets with supply of oxygen, fur !
nished by the atmosphere, to support its combus- |
,ion. The sole product of this combustion of
hydrogen, IS Ipater. If hydrogen be mingled !
win oxygen, IN the proportion of 8 parts, by |,
weight, OF the latter 10 of the former (the ex-
act proportion to form water,) or with such a |
quantity OF atmospheric air as to furnish parts
OF oXygen'to every part of hydrogen, and then. |
flame be applied to the mixture, combination in. |
simultaneously ensues throughout the mass, ac-
companed by an explosion. Here again, water
is the sole product of the combination.
4th. hydrogen is capable of combining with
substances, and forming with them class of
true acids, of which Hydro-chloric or Muratic |
acid may serve as an example.
ON The chemical equivalent, combining pro-
portion, or atomic weight (See Lee. 2nd, Law
9th of Affinity of Hydrogen is 4 !, its atom being
taken as the standard of 1 comparison for The !
atoms OF all other kinds of matter. The atom of
hydrogen, has been taken as The standard Of
comparison, because it is the lightest Of the atoms
OF matter. When we say that the atomic weight
OF oxygen Is 3, we mean not pounds, or ounces,
or grains, but times much as the atom of
hydrogen.
1t VIII be seen at once that these numbers en-
press relative weights only but let il be re-
marked that they not Tie less valuable on this
account, for nothing is more easy, than 20 sub
stItute absolute weights for these relative ones
For instance, know that pure water is compos.
ed OF one atom Of hydrogen united with one of
oxygen, the respective atomic weights of these
elements being and Il know then that for ev
water, there is pound of hydrogen; for every s
ounces OF the former there is ounce of the latter
and so on for any other absolute weights.
9th. Ii stream OF hydrogen be projected up
on piece OF recently prepared spongy platinum.
The platinum soon becomes white, hot and sets
fire to the gas. This fact, with which chemists
have been acquainted for d number of wears. has
| never until recently been satisfactorily explained
AS shall have TO refer TO The principle involved
in the explanation of this fact, when we come to
examine into the manner in which plants convert
the crude sap which they obtain from the soil
| into gum, resin, starch, and the other proximate
elements Of which they are composed, as also
the means which they possess of feeding upon
the atmosphere, will 20 into somewhat min
ute explanation of il al the presen, time In or
der TO do this, however, must first direct your
| attention to species of attraction of which we
have hitherto taken no notice, viz. Capillary at
/ traction.
! Capillary attraction. is generally defined as
that species Of attraction which liquids manifest
| in rising in small tubes, in tubes about the size
Of human hair, and hence the name from The
Latin word capillus, hair. The more impor-
tant of the laws which govern this species of al
traction the following, viz:
| LIST. When capillary tube Of glass, open at
both ends, has one end dipped into vessel Of
/ water, the water will rise in that tube above the
| level of that in the vessel
| 2nj. The height to which water will rise in
different tubes, will vary inversely as the diane
ters Of those tubes, j. e. if it rise 10 a certain
height In tube Of certain size, il will rise twice
as high in tube Of half that diameter.
| Ord. tube OF glass one-huDdredlh Of an inch
in diameter will raise water SD inches Know
ing This law and the one preceding it, we can by