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LXI. Intelligence and Miscellaneous Articles. 



COMPRESSIBILITY OF THE GASES OXYGEN, HYDROGEN, NITROGEN, 

 AND AIR UP TO 3000 ATMOSPHERES. BY M. E. H. AMAGAT. 



T HAVE followed the method which I have already used for study- 

 -*- ing liquids within the same limits of pressure, but the difficulty is 

 here far greater ; it arises more especially from the smallness of the 

 volume which a gas occupies when it is somewhat powerfully com- 

 pressed. After numerous trials, I have arrived at perfectly regular 

 and concordant results by usiug for gauging the platinum-wire 

 tubes the method of reading by electrical contacts, which then 

 served to estimate in the same tubes the volumes successively 

 occupied by the compressed gas. 



I thus obtained for the same gas with different tubes graphical 

 traces which are almost absolutely coincident. 



The results which I give further on, and which are merely 

 apparent results, differ materially (numerically) from those at 

 which batterer arrived. The differences, which are somewhat 

 irregularly distributed amount to several hundredths of atmo- 

 spheres in the part common to our researches ; for the same reduc- 

 tion in the volume of gas I find in general pressures far higher 

 than those given by batterer : this difference can be easily 

 accounted for if we discuss the probable and even inevitable errors 

 inherent in the method pursued by this physicist. The following 

 results refer solely to high pressures ; pressures below 1000 atmo- 

 spheres will be investigated by an apparatus which enables me to 

 raise the temperature far higher than I have been able with very 

 high pressures, where I could only work between 0° and 50°. 



The following table gives for the pressures specified in the first 

 column the volumes occupied at 15°, by unit masses of gas, at the 

 same temperature and under the same pressure, 76 centim. 



Atmospheres. 



Air. 



Nitrogen. 



Oxygen. 



Hydrogen . 



750 

 1000 

 1500 

 2000 

 2500 

 3000 



0002200 

 0001974 

 0001709 

 0-001566 

 0001469 

 0-001401 



0-002262 

 0-002032 

 0-001763 

 0001613 

 0-001515 

 0001446 



0-001735 

 0001492 

 0001373 

 0-001294 

 0001235 



0001688 

 0001344 

 0001161 

 0-001047 

 0-000964 



It is interesting to compare the compressibilities of strongly 

 compressed gases among each other and with liquids. In order to 

 facilitate this comparison I have calculated from 500 atm. to 800 

 atm. their coefficient of compressibility as usually defined with 

 liquids. The following is the table of results obtained : — 



Phil. Mag. S. 5. Vol. 26. No. 163. Dec. 1888. 2 P 



