98 



M. Achille Cazin on Internal Work in Gases. 



It will be remembered that I have mentioned in § V. two ex- 

 periments on hydrogen not given in Series III. They show 

 that the influence only manifests itself for 6 <: 0*1 second. 



Continuation of Series III. 



f 0=08-08 



\h=0 





2-2 



6-2 



11 



16 



24 



60 



+ 19 



-113 



-34 



-13 



-6 



-1 







J 0=0-09 

 [h=-6 





2-3 



6-9 



10-8 



18-4 





60 



+ 13 



-112 



-24 



-14 



-3 









§ VIII. Influence of the arrangement of the channel which joins 

 the two reservoirs. 



Wishing to investigate at the outset of these researches the 

 influence of the mode of communication of the manometer with 

 the copper reservoir A and the glass one B, I had fitted inte- 

 riorly to the tubes D, E (fig. 2) some copper tubes, a a! 3 a l a' lf 

 open at a 1 , a' v so that the interior pressure might be transmitted 

 to the manometer Q, either by the pipe a' aDW R, or by the 

 similar one a\ a 1 E H R. These tubes grazed the sides of the tu- 

 bulures of the reservoirs, and did not seem likely to obstruct the 

 jet of gas when it rushed from A towards B. I was very much 

 astonished, in making some experiments like the preceding, to 

 see the curve take the form of the line nine (fig. 1); h attained 

 the maximum value +250 millims. (water), the difference of 

 pressure P\—p<z being about four atmospheres. This effect was 

 always produced, whatever the value of 6. It underwent no 

 change when an opening was made at the point a x of the tube, 

 when the extremity a\ was closed, and, finally, when both a x 

 and a\ were closed. In this latter case the internal pressure 

 was transmitted to the manometer only by the passage a'aD H'R, 

 whilst in the other cases we used either this passage or the other. 



The tube a Y a\ was suppressed, and then the effects of series 

 V. observed, which are described in § VI. and represented by 

 the line a'b'b"c , i ^. 1. 



It is evident that the anomaly observed was due to the action 

 of the tube a Y a\ on the gaseous jet, and that the tube a a* exer- 

 cised an analogous action, but not so great. Hence this is the 

 explanation of the anomaly : — 



Let us distinguish three parts in the gas of the reservoirs : — 



(1) that which remains in the reservoir A after the expansion; 



(2) that which remains in the reservoir B before the expansion ; 



(3) that which passes from the reservoir A into the reservoir B. 

 When the expansion has taken place, there is equality of pres- 

 sure between these three parts; the magnitude p of this pressure 

 depends on the state in which each is found. It afterwards 

 varies, in proportion as these parts mix together and exchange 

 heat, either with one another or with the sides; and when these 

 exchanges have ended, the pressure attains the final value p'. 



