Oct. 15, 1885 | 
regulating the expansion so as to maintain a certain pressure in 
the tube, the oxygen is seen for some time completely liquefied. 
» When by means of the air-pump the evaporation of liquid 
ethylene is accelerated, as was done by Faraday with protoxide 
of nitrogen and carbonic acid, its temperature is reduced much 
below the critical point of oxygen. 
* With a view to avoiding the inconveniences and complications 
inyolved in the necessity of working iz vacuo, I indicated liquid 
Sorméne, which with the greatest ease achieves the liquefaction 
of oxygen and nitrogen. Notwithstanding these advantages, in 
consequence of the perfection to which I have recently brought 
the preparation and management of ethylene, it has seemed to 
me that this substance should be preferred to formene, and so, 
by means of boiling ethylene in open vessels, I have succeeded 
in obtaining a temperature sufficiently low for the complete 
liquefaction of oxygen. 
The preparation of ethylene by means of sulphuric acid and 
alcohol is frequently impeded by the frothing of the material, 
terminating the experiment before the gas has been com- 
pletely liberated. The admixture of sand, recommended by 
Wohler, does not always serve to counteract this frothing, but 
T have found the addition of a small quantity of vaseline effica- 
cious in this respect. 
NATURE 
585 
The material I work with consists of 400 grammes of alcohol, 
2000 grammes of sulphuric acid, and 15 to 20 grammes of vase- 
line. This is warmed in a glass globe, of 5 or 6 litres capacity, 
over a burner in the usual way. The gas is washed in two 
large flasks of caustic soda, and then collected in a water gas- 
holder. By means of a mercury pump the ethylene is dried by 
passing through a flask of sulphuric acid and condensed in steel 
bottles having a screw tap. 
Fig. I represents the apparatus I made use of to liquefy 
oxygen by the rapid evaporation of ethylene by means of 
a current of air or of refrigerated hydrogen. The liquid 
ethylene is inclosed in the bottle E, which is fixed to a vertical 
support, with its mouth directed downwards, and is in communi- 
cation with a copper worm, ss, of 3 mm. to 4 mm. in diameter, 
closed at its lower extremity by a screw cock, 7’. After the 
worm has been cooled to — 70° by means of chloride of methy- 
lene in the manner I shall explain further on, the ethylene there 
accumulating possesses at this temperature but a weak tension, 
and it may therefore be run without sensible loss into the test- 
tube, L, when the cock, 7”, is opened. This new arrangement 
I have adopted for ethylene and formene allows the liquefied 
gas to be cooled as well as though the whole reservoir containing 
it were of the same temperature as the worm. 
r 
Fic. 2. 
The glass test-tube L is arranged in a vessel containing, air 
dried by means of pumice and sulphuric Gc’, and in this way hoar- 
frost is prevented from being deposited on the refrigerated sides. 
When the ethylene has been received in the test-tube L, 
its evaporation is accelerated by passing through it a cur- 
rent of air, or, still better, of hydrogen dried by its passage in 
the vessel Cc, containing chloride of calcium, and cooled in the 
worm Ss’. 
The two worms in which the air and the ethylene circulate 
are plunged into chloride of methylene which is rapidly evapor- 
ated by means of dry and cool air, and in this way a temperature 
of — 70° is obtained. 
Fig. 2 shows the arrangement of the oxygen apparatus and 
the compression pump. When the tube To is plunged into the 
ethylene, the evaporation of the latter is accelerated by gently 
opening the cock F, and blowing on to it the air or hydrogen 
cooled in the worm s’. 
The pump is then brought into action, and the oxygen re- 
solves into a colourless, transparent liquid, separated from the 
gas surmounting it by a perfectly sharp meniscus. 
By means of a hydrogen thermometer, the construction of 
which I shall shortly explain, I have measured the temperature 
of the ethylene, which in one of my experiments was found to 
be —123°C. By dint of certain modifications effected in the 
apparatus I am in hopes of achieving a still lower temperature. 
Altogether, I have proved that by quickening the evaporation 
of the ethylene by means of a current of air or hydrogen cooled 
to a low degree, its temperature is lowered much under that 
of the critical point of oxygen, and that in such a medium the 
oxygen liquefies most easilyr! 
This experiment is so easy of accomplishment, that the 
practice of it may be commenced at once in laboratories, and be 
repeated in public lectures. 
The apparatus I have described has been constructed with 
great care by M. Ducretet, and I have to thank M. *Jamin 
for kindly permitting me to perform the experiments in the 
Physical Laboratory of the Sorbonne. 
1 M. E. Sainte-Claire Deville, engineer to the Gas Company of Paris, and 
son of my illustrious master, has now for some time, by my advice, been 
studying the problem of lowering the temperature by means of the rapid 
evaporation of chloride of methylene, and has established that, by sufficiently 
cooling the injected air, temperatures varying from —23° C., to —72° C. may 
be maintained nearly constant for several hours. 
