324 



Intelligence and Miscellaneous Articles. 



We know that this theory leads to this formula when we suppose 

 the internal work due to the change undergone by the gas equal to 

 zero. It would seem that this does not hold for carbonic acid, the 

 internal work of which is considerable. M. Hirn has put forward a 

 theory applicable to this case which leads to the same formula ; 

 my experiments are consequently favourable to this theory ; but 1 

 ought to remark that this law represents an ideal expansion which 

 cannot be realized, and it will be seen that real expansions comport 

 themselves differently. 



Second mode oj observation. — We keep p 1 constant and vary p 2 . It 

 is thus that I have studied expansion from a pressure of 9 atmo- 

 spheres to 5, 4, 3, .... atmospheres. The principal results of this 

 investigation are given in the annexed Table. 



p i = 6576 millims. of mercury, p L = 6'61302. 

 The specific gravity p = l under a pressure of 1000 millims. 



Air. 



p-2. 



Pz- 



At 



e. 



Ay. 



p 2 . 



p'- 



P"- 



p"-p'. 



0-07860 

 0-08803 

 0-05930 

 0-06370 

 0-06066 



4219 

 2998 

 2173 

 1437 

 769 



4728-0 

 3685-0 

 2925-9 

 2156-5 

 1349-7 



29-4 

 50-9 

 70-2 

 91-0 

 117-4 



s. 



0-15 



0-23 



0-40 



0-54 



0-70 



0-00610 

 000590 

 0-01080 

 0-01321 

 0-02341 



4-74641 

 3-69553 

 2-93198 

 2-15923 

 1-35022 



4-74861 

 3-70043 

 2-94618 

 2-18513 

 1-38272 



4-82721 



3-78846 

 3-00548 

 2-24883 

 i-44338 



Carbonic acid. 



3285 3838-9 



20732686-8 



811 1275-1 



13-4 

 62-3 

 99-3 



0-42 

 0-64 

 112 



0-0045 

 0-0070 

 0-0061 



3-93501 

 2-72537 

 1-27795 



3-93947 

 2-74074 

 1-31483 



4-56492 

 3-46253 

 1-94386 



0-62545 

 0-72179 

 0-62903 



The specific gravities have been calculated by the help of M. Reg- 

 nault's formulas for the compressibility of gases. 



At is the decrement of the temperature, calculated according to 

 p x andj9 3 by means of Gay-Lussac's law. 



Ay is the diminution of the ordinate for the lower branch of the 

 curve which represents each series, corresponding to an increment 

 of the abscissa equal to one second. It is by means of these 

 values that the correction relative to the sides has been made. 



jo 2 is the observed specific weight without any correction. 

 p is this weight corrected according to the thermic action of the sides. 



p" is this weight calculated from the formula of Laplace and 

 Poisson with m=l*41 for air and 1*291 for carbonic acid. 



If we calculate the differences p" — p 2 , we find quantities which, 

 according as p 2 diminishes, vary very little for air, but which for 

 carbonic acid first increase, then decrease. The result shows that 

 the real specific gravity at the end of the expansion is always smaller 

 than if the gas followed the preceding law, and that the deviation 

 cannot be solely due to the influence of the sides ; for according as 



