314 Intelligence and Miscellaneous Articles. 
For oxygen and nitrogen the direction of the rectilinear parts is 
not yet sufficiently marked, and to obtain it far higher pressures 
must be obtained than has hitherto been the case. With this 
view I have constructed apparatus in which I have been able 
to compress gas to about 4000 atms. ‘Two accidents in succession 
have hitherto prevented me from making regular numerical 
determinations; but I may already announce the following result :— 
I have frequently reduced oxygen to the nine-hundredth of its 
volume ; in these conditions its density was far higher than that 
of water; with the greatest pressure I could produce, density 
was higher than 1°25, and this when the surrounding temperature 
was 17°; we must therefore abandon the idea of unity as a 
limiting density. 
Compared with hydrogen, numbers are given as the density of 
this body in the liquid state which present such extraordinary 
differences that I shall not attempt to discuss them. The limiting 
density, as deduced from my own experiments, is very nearly equal 
to 0:12. Referring to the curve of L. Meyer, it follows that the top 
of the ordinate which represents the atomic volume of hydrogen 
will be on the prolongation of the curve, passing through the tops 
of lithium, of sodium, and of potassium. ‘This would enable us, in 
conformity with the ideas of Dumas, to assume between this body 
and lithium a period analogous to those which succeed, but in 
which, it is true, no known body could be placed. 
The two accidents mentioned above appear to me to present 
sufficient interest to be noticed. In one of the experiments the 
gas-manometer was contained in a cylinder of cast steel with very 
thick sides, and with mercury in the bottom. All at once a 
screeching sound was heard, and a jet of pulverized mercury was 
shot through the right section of the breach, striking the base of the 
apparatus, and bounding off to more than 1 metre in all directions, 
producing the same sound as steam escaping from a high-pressure 
boiler ; the section showed no defect when seen under the micro- 
scope. We have therefore before us the classical experiment of 
the mercurial rain in the form of a true jet of mercury passing 
through the pores of steel through a thickness of 0°08 metre. The 
pressure was certainly at least 4000 atmospheres; the same appa- 
ratus under the same pressure does not allow a drop of glycerine 
to pass; this is probably the case also for water and other liquids. 
Another apparatus, a solid block of steel with a closer grain, 
weighing 116 kilog., was split parallel to the axes of the cylinder, 
and although there was neither projection, nor even separation of 
the parts any more than a sudden entrance of the gas, the fracture 
took place with extreme violence ; the mercury escaped through 
the crack, as I had time to observe, i in the form of a bright plane 
vertical metallic sheet of 0:06 to 0-07 metre in breadth, 
Among other apparatus which I have used for measuring 
pressure, I may mention a manometer of Desgoffe’s, in which I have 
introduced the improvement already pointed out by M. Meraud 
Deprey for piston-manometers. This apparatus should give ex- 
