G2 
rEOFESSOE W. EAMSAY AND DE. M. W. TEAVEES 
neglecting to refractionate the tirst distillate : but as our object was to procure 
pu]*e neon, and not pure beliiun, tliis was of no consequence. 
The density of this neon was determined independently by each of us. 
Volume of bulb. 
Weight of gas . 
Pressure . 
Temperature. 
Density of neon 
W. It 
32'038 cub. centims. 
0'01 too gramme. 
306 '5 minims. 
292'05° abs. 
9-99 
M. W. T. 
32’038 cub. centims. 
0‘01120 gramme. 
313‘8 millims 
292-2° abs. 
9-94 
llie Preparation of Krypton and Xenon. 
These gases are left behind after the evaporation of liquid air, along with a large 
quantity of oxygen and some nitrogen. It has been necessary to use considerable 
(piantities of liquid air for refrigerating puiposes, and in almost all cases, the I'esidue 
of a feAV cub. centims., instead of being allowed to evaporate away, was collected in 
a gasholder. When a sufficient quantity liad accumulated, the oxygen was removed 
by combustion with hydrogen in the following manner :— 
An iron tube, about half an incli in internal diameter, tilled with platinised 
asbestos, was heated to redness in a long-tlame gas burner. At one end of the tube an 
arrangement like a Idowpipe was attaclied by screwing, and through one of the tubes 
a current of hydrogen entered from a Kipp’s apparatus, while through the other the 
mixture containing the rare gases was admitted. These gases burned, and by regulating 
the stop-cocks, it was possible to adjust tlie proportions fairly well. But to make it 
possible to leave the ojiei'ation to itself, and to render it in a sense automatic, a tell¬ 
tale tube of hard glass, containing copper oxide in one half, and metallic copper in the 
other, was connected with the other end of the iron tube : so that if excess of oxygen 
])assed it oxidised the coppei-, and if excess of hydrogen, it reduced the co})per oxide. 
The further end of the glass tube was connected Avith a reservoir, and with a gasholder. 
The water produced condensed in the reservoir, Avhicli was so arranged that it 
could be run off from time to time ; and the gases, now free from oxygen, passed 
into the gasholder. The nitrogen was next removed AA'ith a mixture of lime and 
magnesium. This mixture, as already stated by MAypu<:xN£, absorbs nitrogen at a 
much lower temperature than magnesium itself, and consequently it is not difficult 
to manipulate it in hard-glass tubes. The only j)recaution required is that the lime 
must be free from hydroxide and carbonate, for,' if not, the magnesium is apt to act 
so quickly on these inq)urities as to i)roduce a rush of gas,—hydrogen and carbon 
monoxide—-so rapid as practically to amount to an explosion. The lime, therefore, 
should be made directly before use, by heating precipitated carbonate in a muffle for 
several hours; and it is conveniently mixed Avith magnesium powder immediately 
before using, in about equal })ro})ortions. Cure must be taken to pass the current of 
