.,
,
378
16.
VACUUM TECHNIQUE
.
a calcium chloride tube, then over hot copper shavings or a hot
copper
wire (heated dull red), then through a phosphorus pentoxide
tube.
The rst and last tubes take out the water vapor and the
copper
combines with the oxygen
to form copper oxide.
Hydrogen
mixed in proper proportion with oxygen or air is explosive so that
the.hydrogen should be passed through the system for a short time
-
before heating up
the copper.
The safe condition may be determined by passing the gas, as it leaves the last tube, into an inverted
test tube.
When the gas has owed for a short time, remove the
test tube a few feet away, keeping it inverted, and apply a match.
If the hydrogen burns rather than giving a gentle explosion it is
'
safe to start the heating.
,
Tank nitrogen contains oxygen and water vapor
which are
removed as with hydrogen. It is not necessary
to take any pre—
caution against explosions.
_
Tank helium contains hydrogen and water vapor.
The latter
:
is removed with calcium chloride and phosphorus pentoxide as
before.
The middle tube should contain black copper
oxide heated
to dull red.
The copper oxide combines with the hydrogen to form
copper and water.
Another way is to circulate the gas over heated,
out—gassed charcoal, using liquid air to freeze out the vapors.
"
To reduce the amount of oxygen in tank argon or tank helium
(from say
6 to 1 per cent), pass
the gas slowly through a liquid
air trap.
For further purication, expose
the gas for 12 hours to ;_
'
a hot tungsten lament operated at approximately 1100° C.
_—
Any one of the rare gases may be puried by passing it through
a chamber in which a spark is occurring between misch‘ metal elec+
trodes, or an arc
between calcium electrodes.
Misch metal
a
miXture of rare
and absorbs nitrogen very readily. _—_
‘
Tank oxygen, made from liquid air, contains nitrogen wh1ch
"*
isdifculttoremove. ,Water vapor should be taken out with phos—
ff
Oxygen from electrolysis contains water vapor
andhydrogenwh1chare removed with CaCl, ’P2Q5_ and heated
copperomäeasmthecaseofhehum _
-
.
St1cksofpotassmm ".hydroxidè«(KOH)1—in
server©
—
.
removecarbondwxe fromthe system
»
<
fè Îçeuteumasàst
'Obfäîed »‘by! passmg the vapmofheaVY
Wâtefthf0ughlmc1mgsat350 C Thedeutermmomdedecm
PasesmœzmcOXIdeanddeutermm(z)…
the
,
378
16.
VACUUM TECHNIQUE
.
a calcium chloride tube, then over hot copper shavings or a hot
copper
wire (heated dull red), then through a phosphorus pentoxide
tube.
The rst and last tubes take out the water vapor and the
copper
combines with the oxygen
to form copper oxide.
Hydrogen
mixed in proper proportion with oxygen or air is explosive so that
the.hydrogen should be passed through the system for a short time
-
before heating up
the copper.
The safe condition may be determined by passing the gas, as it leaves the last tube, into an inverted
test tube.
When the gas has owed for a short time, remove the
test tube a few feet away, keeping it inverted, and apply a match.
If the hydrogen burns rather than giving a gentle explosion it is
'
safe to start the heating.
,
Tank nitrogen contains oxygen and water vapor
which are
removed as with hydrogen. It is not necessary
to take any pre—
caution against explosions.
_
Tank helium contains hydrogen and water vapor.
The latter
:
is removed with calcium chloride and phosphorus pentoxide as
before.
The middle tube should contain black copper
oxide heated
to dull red.
The copper oxide combines with the hydrogen to form
copper and water.
Another way is to circulate the gas over heated,
out—gassed charcoal, using liquid air to freeze out the vapors.
"
To reduce the amount of oxygen in tank argon or tank helium
(from say
6 to 1 per cent), pass
the gas slowly through a liquid
air trap.
For further purication, expose
the gas for 12 hours to ;_
'
a hot tungsten lament operated at approximately 1100° C.
_—
Any one of the rare gases may be puried by passing it through
a chamber in which a spark is occurring between misch‘ metal elec+
trodes, or an arc
between calcium electrodes.
Misch metal
a
miXture of rare
and absorbs nitrogen very readily. _—_
‘
Tank oxygen, made from liquid air, contains nitrogen wh1ch
"*
isdifculttoremove. ,Water vapor should be taken out with phos—
ff
Oxygen from electrolysis contains water vapor
andhydrogenwh1chare removed with CaCl, ’P2Q5_ and heated
copperomäeasmthecaseofhehum _
-
.
St1cksofpotassmm ".hydroxidè«(KOH)1—in
server©
—
.
removecarbondwxe fromthe system
»
<
fè Îçeuteumasàst
'Obfäîed »‘by! passmg the vapmofheaVY
Wâtefthf0ughlmc1mgsat350 C Thedeutermmomdedecm
PasesmœzmcOXIdeanddeutermm(z)…
the