16—19.
INTRODUCING GASES
377
small ame is applied to the constriction, the tube fused together,
and the chamber pulled' off.
_
.
16—19.
Introducing.
a small but constant leak
of gas into a vacuum system is desired, one may use a long, ne
capillary tube. For a slower rate of leakage, a value may be used
in which a ne needle nearly closes a small, gently tapered hole,
The mechanical device to adjust the position of the needle in the.
hole, to control the rate of leakage, may be made air tight with a
sylphon bellows.
'
*
As shown in gure 3—6, a small piece of lavite, pointed on the
end, may be waxed in the end of a glass tube and surrounded With
mercury, leaving such an amount of the tip projecting as to give
’
the desired rate of leakage thrbugh this semiporous material into
the vacuum system,
-
.
‘
.
A bent, attenedmetal tube may be used as a valve to control
the rate of ow of a gas into a vacuum system. Themore it is
,
bent, the slower the leak.
'
,
A small crack in a glass tube may
also be used as a valve;
'
Twisting the tube Will open
the crack and increase the ow of
gas through it. «
'
'
In order to introduce hydrogen into a vacuum system, a '
palladium tube is sealed into the system as at ], gure 16—12.
_
If a bunsen ame is’ applied with the tip of its inner cone (the
—
oxidizing part) on the palladium, hydrogen-will be__drawn
out of
the system.
If the Outer part
of the ame is applied, hydrogen
Will pass into the vacuum. The palladium thimble should
not be
_
heated red hot.
,
’
_
K in gure'16—12 is a platinum tube, some .20
cm. long,
1 mm.
in diameter, with walls 0.1
thick, sealed in a
soft glass tube
attachedto the pyrex system through the graded seal
L.
'
Tank hydrogen ows over the platinum
tube at a rate 1nd1cated
'
by the bubbling in the water M and is burned at N. Ifthe platr—
num is heated to 500° C. by a battery (20 volts, 1_5 amperes) f3r
a
Step down transf0rmer, it allows pure hydrogen t0 OW SÏOW1Y 1nto
the system.
The hotter it is, the faster the hydrogen
_
it may _,be used as a valve and also
as a purier of the
gas
.
—
ehtering the vacuum
—
_
‘
_
'
_
Purifyig
mam things to
from
È tank hydrogen are oxygen and water Vapor.
Pass the gas through
INTRODUCING GASES
377
small ame is applied to the constriction, the tube fused together,
and the chamber pulled' off.
_
.
16—19.
Introducing.
a small but constant leak
of gas into a vacuum system is desired, one may use a long, ne
capillary tube. For a slower rate of leakage, a value may be used
in which a ne needle nearly closes a small, gently tapered hole,
The mechanical device to adjust the position of the needle in the.
hole, to control the rate of leakage, may be made air tight with a
sylphon bellows.
'
*
As shown in gure 3—6, a small piece of lavite, pointed on the
end, may be waxed in the end of a glass tube and surrounded With
mercury, leaving such an amount of the tip projecting as to give
’
the desired rate of leakage thrbugh this semiporous material into
the vacuum system,
-
.
‘
.
A bent, attenedmetal tube may be used as a valve to control
the rate of ow of a gas into a vacuum system. Themore it is
,
bent, the slower the leak.
'
,
A small crack in a glass tube may
also be used as a valve;
'
Twisting the tube Will open
the crack and increase the ow of
gas through it. «
'
'
In order to introduce hydrogen into a vacuum system, a '
palladium tube is sealed into the system as at ], gure 16—12.
_
If a bunsen ame is’ applied with the tip of its inner cone (the
—
oxidizing part) on the palladium, hydrogen-will be__drawn
out of
the system.
If the Outer part
of the ame is applied, hydrogen
Will pass into the vacuum. The palladium thimble should
not be
_
heated red hot.
,
’
_
K in gure'16—12 is a platinum tube, some .20
cm. long,
1 mm.
in diameter, with walls 0.1
thick, sealed in a
soft glass tube
attachedto the pyrex system through the graded seal
L.
'
Tank hydrogen ows over the platinum
tube at a rate 1nd1cated
'
by the bubbling in the water M and is burned at N. Ifthe platr—
num is heated to 500° C. by a battery (20 volts, 1_5 amperes) f3r
a
Step down transf0rmer, it allows pure hydrogen t0 OW SÏOW1Y 1nto
the system.
The hotter it is, the faster the hydrogen
_
it may _,be used as a valve and also
as a purier of the
gas
.
—
ehtering the vacuum
—
_
‘
_
'
_
Purifyig
mam things to
from
È tank hydrogen are oxygen and water Vapor.
Pass the gas through