M. Achille Cazin on Internal Work in Gases. 



M 



Series VI. (September 1867). 



Dry air. Manometer communicating with the tube H 7 (fig. 2). 



jt? 1 = 3'86 atmospheres, p 2 =. 0*22 atmosphere. Temperature 19°. 



/ 0=0^10 

 \h=-Z mm 



t=... 



37 



8-9 



13-6 



203 



24 



54 



120 



+92 



-40 



+ 10 



+ 18 



+ 16 



+14 



+3 







f 0= 0-21 

 1 A=-3 



... 



3-3 



8-1 



138 



231 





53 



120 



+22 



-73 



-17 



+8 



+ 11 





+4 







J 0=030 

 *U=-4 





2-9 



66 



9-7 



142 



24 



54 



120 



... 



-88 



-25 



+« 



+ 19 



+ 15 



+6 







f 0=0-38 

 \h= 



... 



2-9 



6 



S-2 



113 



15 3 



24 



120 





-99 



-42 



-10 



+ 10 



+ 18 



+ 14 







J 0=0-92 

 \h=-2 





3-2 



M 



10-5 



161 



25 



55 



120 



... 



-88 



-21 



+9 



+ 17 



+ 12 



+1 







It will be seen, in tracing the curves of this series, that when the 

 valve of the manometer is opened after a time < 030 second, 

 the exterior level of the manometric liquid rises at first very ra- 

 pidly higher the lower 6 is, and afterwards redescends and com- 

 ports itself as before. The form of the first two curves of Series 

 VI. is that of the line a' b' b" c' of fig. 1. 



It is easy to explain this peculiarity. Before the expansion 

 commences, the tube DH'R and the reservoir A are filled with 

 compressed gas. When the expansion commences, and before 

 the valve R is opened, the gas in the tube DH'R escapes into 

 the reservoir A ; and it may happen that the valve opens before 

 the tube is emptied. Then the manometer indicates a momentary 

 increase of pressure, until equilibrium is again established 

 throughout the tube. An analogous effect may be produced in 

 Series I. on account of rarefaction in the tube S R : the de- 

 pression of the level will be increased by this effect for small 

 values of 6. But the difference of pressure between the reser- 

 voir B and the tube S R is much less than between the reservoir 

 A and the tube D H' R. Moreover I used for S R a wide and 

 short lead tube. This kind of influence is therefore altogether 

 insignificant in experiments arranged like those of Series I. 



It must be observed that if 6 > 0'30 second, the results are 

 the same in the two series ; so that it is a matter of indifference 

 whether the manometer communicates with the tubulures S, H', 

 or even H (as was the case with the glass reservoir B), on con- 

 dition that we do not take too small. 



Comparisons analogous to those I have just mentioned have 

 been frequently repeated ; and they all lead to the conclusion 

 that equality of pressure establishes itself very quickly in the 

 reservoirs, and that it afterwards maintains itself, as is repre- 

 sented by the line g h i e } fig. 5, whilst the various portions of 

 the gas exchange among themselves motion and heat. 



Phil. Mag. S. 4. Vol. 40. No. 265. Aug. 1870. H 



