LIQUEFACTION OF OXYGEN. 751 



In the interior of the carbonic acid tube passes a fourth tube, intended 

 tor the compression of oxygen ; it is 5 metres long and 14 millimetres in 

 external diameter. Its internal diameter is 4 millimetres. This long tube 

 is consequently immersed in solid carbonic acid, and its whole surface is 

 brought to the lowest obtainable temperature. These two long tubes are 

 connected by the ends of the carbonic acid tube, consequently the small tube 

 extends about 1 metre be^'ond the other. I have curved this portion down- 

 ward and given the two long tubes a slightl}^ inclined position, but still very 

 near the horizontal. 



The small central tube is curved and screws into the neck of a large 

 howitzer shell, the sides of which are 35 millimetres thick; the height is 

 28 centimetres, and the diameter 17 centimetres. 



This shell contains 700 grnis. of chlorate of potash and 256 grms. of chlo- 

 ride of potassium mixed together, fused, then broken up, and inti'oduced into 

 thu shell perfectly drj-. 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 decomposition of the chlorate of 

 potash takes place at first gradually, then rather suddenly towards the end 

 of the operation. A pressure-gauge at the extremity of the long tube, lets 

 me constant!}^ observe the pressure and the progress of the reaction. This 

 gauge is graduated to 850 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 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, how^- 

 ever — can be obtained. 



Pieces of charcoal, slightly incandescent, put in this jet inflame sponta- 

 neously 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 possi- 

 bly 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 characterized, 

 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 utilize a similar arrangement in attempting the condensation 

 of hydrogen and nitrogen, and I am especially occupied with the possibility 

 of maintaining low temperature very easily, thanks to four large industrial 

 pumps which I have at my disposal, worke'd by a steam engine. 



Geneva, December 25, 1877. 



Since receiving the above we have been favored with further particulars 



