244 
Liquefaction of Oxygen. 
[April, 
then broken up, and introduced into the shell perfectly dry. 
When the double circulation of the sulphurous and carbonic 
acids has lowered the temperature to the required degree, I 
heat the shell over a series of gas-burners. The decompo- 
sition of the chlorate of potash takes place at first gradually, 
then rather suddenly towards the end of the operation. A 
pressure-gauge, M, at the extremity of the long tube, lets me 
constantly observe the pressure and the progress of the re- 
action. This gauge is graduated to 800 atmospheres, and 
was made for me expressly by Bourdon, of Paris. 
When the reaction is terminated the pressure exceeds 
500 atmospheres ; but it almost immediately sinks a little, 
and stops at 320 atmospheres. If at this moment I open 
the screw-tap, r, which terminates the tube, a jet of liquid is 
distinctly seen to spirt out with extreme violence. I close 
the tap, and in the course of a few moments a second jet — - 
less abundant, however, can be obtained. 
Pieces of charcoal, slightly incandescent, put in this jet 
inflame spontaneously with inconceivable violence. I have 
not yet succeeded in collecting the liquid, on account of the 
considerable projectile force with which it escapes, but I am 
trying to arrange a pipette, previously cooled, which possibly 
may be able to retain a little of this liquid. 
Yesterday I repeated this experiment before the majority 
of the members of our Physical Society, and we had three 
successive jets, well characterised. I cannot yet determine 
the minimum pressure necessary, for it is evident that I have 
a surplus pressure produced by the excess of gas accumulated 
in the shell, and which could not condense in the small space 
represented by the interior tube. 
I hope to utilise a similar arrangement in atempting the 
condensation of hydrogen and nitrogen, and I am especially 
occupied with the possibility of maintaining low temperatures 
very easily, thanks to four large industrial pumps which I 
have at my disposal, worked by a steam-engine. 
The following experiment was performed for the fourth 
time on Thursday, December 27th, in the presence of ten 
scientific men — among others, Prof. Hagenbach, of Bale, 
who came expressly to assist at this important experiment, 
the success of which called forth the applause of all 
present : — 
At 10 o’clock in the evening the manometer, which had 
risen to 560 atmospheres, sank in a few minutes to 505, 
and remained stationary at this figure for more than half-an- 
hour, showing by this diminution in the pressure that part 
