142 Screntific Intelligence. 
MM. Pictet has done; on being separated from its enormous pres- 
sure it has merely put on on the — of a cloud. 
M. Cailletet first introduced pure nitrogen gas into the appa- 
ratus, Undera pressure of 200 atmospheres the tube was opened, 
and a number of drops of liquid nitrogen were formed. Hydro- 
n was hext experimented with, and this, the lightest and most 
difficult, of all gases, was 8 reduce to the form of a mist at 280 
present at the experiment estimated it at —300 
Although oxygen and nitrogen h ad both been liquefied, it was 
deemed of interest to carry out the process with air, and t 
eo was filled with the latter, carefully dried and freed from 
carbonic acid. The xp yielded the same 
3. On the Lie Soctiee ‘of Acetylene, Ethyl hydride, Nitrogen 
dioxide and ly Mars. AILLETET, studying the com- 
pressibility ot acetylene, seeds a amarked departure from the law 
f Mariotte in its behavior, and, pushing the condensation still 
further, succeeded in liquefying it. The apparatus consisted of a 
ac a i the temperature bei ais gens tans 1 
seen to form and run down the walls of the tube, under a pre 
of eighty-three atmospheres. R the pressure gradually, 
ragerelty a pears to hl refractive, and is lighter than water 
which ais soluble Eas | proportions. It dissolves paraffin 
and fats. Cooled to zero in presence of water and linseed oil, it 
forms a white compound like snow, which decomposes on heating 
or lowering the pressure. The tension of the acetylene vapor 
is as follows: at +1°, 48 pera sar at 2°5, 50; at 10, 
63; at 18°, 83; at 25°, 94; at 31° Com omparing t the tensions 
of acetylene, ethylene, and ethyl i (C,H,) which con- 
tain in equal volumes, equal weights ts of carbon united to increas- 
ing quantities of hydrogen in the ratio 1:2: 3, the author finds 
the tension of acetelyne at 1°, as above, to be "forty-four atmo- 
spheres ; that of ethylene at 0° according to Semen: being forty- 
six atmospheres, and that of ethylene hydride—now liquefied for 
