( 616 ) 
A, a dry gas meter, (air inlet). 
B, two poiash drying towers. 
C, three iron tubes!) containing a mixture of 90% calcium carbide and 10°/, 
calcium chloride, heated in a coke furnace so as to absorb oxygen and nitrogen. 
D, a porcelain tube containing copper oxide, and heated in a chemical combus- 
tion furnace so as to get rid of hydrocarbons (especially acetylene). 
E, two drying tubes containing potash and phosphorus pentoxide. 
F, a mercury jet circulating pump (more detailed in Fig. 2). 
G, Tépler pump for drawing off the gas that has been treated and an oil gaso- 
meter for storing it in. 
During the working cycle the valves C, and C are closed; the gas travels the 
path indicated by arrows. 
Fig. 2.°) Apparatus for a working cycle over HEMPEL mixture. 
A, iron tube containing Hempet mixture, and heated in a chemical combustion 
furnace for absorption of nitrogen. 
B, a hard glass tube of copper oxide heated in a smail furnace to absorb traces 
of hydrocarbons that come from the mixture. * 
C, two drying towers filled with potash and phosphorus pentoxide, 
D, circulating pump: a Prytz-pump D, worked by an electric motor Dj raises 
the mercury. The mercury does not pass through any taps, and the apparatus 
can be evacuated without allowing any air to force its way in through the punip. 
The pump can be worked for all pressures in the apparatus less than 1 atm. If 
the tube cf the Prytzpump breaks the gas in the apparatus can neither escape 
nor be contaminated. 
i, side tubes for removing and supplying gas. 
F, manometer. 
G, two vessels each of about 5 L. content, to increase tbe capacity of the apparatus. 
H, phosphorus pentoxide drying tube. 
I, a side tube to allow of the removal of the gases developed when the Hemper 
mixture is heated at the beginning. 
J, side tube for the removal of the purified gas, which is then stored in a high 
pressure cylinder as shown in Fig. 3. 
Fig. 3.% Apparatus for the separation of argon and neon by 
fractional distillation. 
A, High pressure cylinder containing argon still contaminated with neon. 
B, manometer. 
C, reservoir surrounded by liquid oxygen boiling under strongly reduced pressure ; 
in this the argon freezes. A mercury suction pump £ brings the neon along D 
to the bulb IF. A Töpler pump then removes the argon along G. H is the pressure 
side of this pump, from which the argon at an over pressure of about 1 atm. is 
passed into the chamber J, immersed in liquid air boiling under reduced pressure. 
When that chamber is filled with solid argon, it is warmed, and the gas blows 
off to the pure gas storage cylinder J. 
1) These tubes, have already served for the preparation of helium, cf. Proc. 
May-June 1908, Comm. N°. 108. 
2) Proc. May 1910. Comm. N°, 115, Part. I § le. 
5) Proc. May 1910. Comm. N°. 115, Part. I. § 3, 
