308 Intelligence and Miscellaneous Articles. 



placed by - 5 e being a conveniently chosen factor. Relation (1) 

 thus becomes : — 



ReT _ Ke : 

 P v- e a T(v+e/3) 2 ' 

 The volume of the gas under the normal pressure at zero being 

 taken as unit, it follows from the properties of perfect gases that 



Re becomes = i r= h . The factor e is therefore determined. 



3. The Compressibility and Critical Point of Oxygen. — The cal- 

 culation, applied to two series of experiments on oxygen *, leads to 

 the following values : — 



log B= 1-23676; logK=7-08424 ; a=4-19 ; /3=323. 



If with these coefficients, and employing measured volumes, we 

 calculate the corresponding pressures, we find the numbers in the 

 following Table, from which the accuracy of the formula can be 

 appreciated : — 



Temperature 14°-7. Temperature 100°-2. 



Pressure. Pressure. 























Calcu- 



Differ- 







Calcu- 



Differ 



7 olume. 



Measured 



lated. 



ence. 



Volume. 



Measured. 



lated. 



ence. 





atrn. 



atrn. 



atm. 





atm. 



atm. 



atm 



40-90 . 



.... 1134 



1136 



-0-2 



45-57 . 



141-1 



1419 



-0-8 



32-78 . 



.... 141-1 



141-1 



00 



35-97 . 



181-1 



181-4 



-0-3 



25-67 . 



.... 181-1 



1805 



4-06 



27-52 . 



240-9 



241-5 



-0-6 



19-56 . 



.... 240-9 



241-7 



-0-8 



20-20 . 



3421 



342-8 



-0-7 



14-59 . 



.... 342-1 



344-3 



—2-2 



17-16 . 



418-9 



418-1 



+0-8 



12-74 . 



.... 418-9 



414-8 



+4-1 











Adopting for the unit of pressure the atmospheric pressure, and 

 for the unit of volume the volume of the gas at zero under the 

 pressure of the atmosphere, the four constants of the formula are. 

 for oxygen, 



R=0-00306o, X = 0-5475, a=0-000b90, /3 = O-0006>0 ; 

 and for the critical point the values of the variables, calculated by 

 the formula; (2), are 



^=0-004042, / c =-105°-4, p e = 48-7 atm. 



These numbers lead to a remarkable consequence. M. Raoul 

 Pictet measured the density of solid oxygen at the temperature of 

 about —110°, under the pressure of 470 atmospheres. If we seek, 

 by meaus of the formula, the corresponding value of v, we find 

 0-00136. Applying this result to the unit of weight, and taking 

 the litre as unit, we find 0-00136 x 007-2 = 0-948. The density, 

 therefore, is very close to unity, in accordance with the valuation 

 of M. Raoul Pictet. In an early communication I will make known 

 the results relative to the other gases investigated by M. Auiagat. 

 — Comptes Rendas de VAcademie des Sciences. March 6, 1882, 

 t. xciv. pp. 639-642. 



* Cvinptes Rendu.*, Nov. 15, 1880. 



