BKTWKKX <>XK ATMOSI'IIKKK AXD HALF AX ATMOSI'MKI.'K UK I'UKXSUKK. ."-I 1 , I 



In the first oljeervation V, is the volume of the two large bull** together and 0, 

 the temperature of the water-lth, reckoned from some convenient neighbouring 



li-lii|ii-r.-il Mi.- .1-- >l;ili>l;i|->l V i-~ tin- Hli'_;:iir_;.-<l M'lmiir :i 1 1 i-;u 1 V i ll-'-ll^si-i 1 \\linM- 



temperature T t is given by the upper thermometer. V 5 is the (larger) volume in the 

 side apparatus whose temperature t l is that of the associated thermometer. In the 

 second ol nervation V, is the (mean) volume of a single bulb and 0., its temperature. 

 V + is the volume in the side apparatus whose temperature, as well as that of V 3 , is 

 taken to be T 2 . III. and IV. represent the corresponding observations when the 

 large bulbs are not used The temperatures of the mercury in the inanometric 

 columns are represented by TJ, TJ, TJ, r v 



As an example of the actual quantities, the observations on hydrogen, April 9-24, 

 1903, may be taken. The values of Vj and V 3 are approximate. 



V, = 632-6, V 3 = 11-02, V 5 = 13-978, V 4 = 1'504, 



V 5 -V 5 = -'650, V 4 -V 4 = -'245. 



0i= -007, 2 =+'OOl; , = +-31, < 3 = '01. 



T, = +-69, T 2 = +78, T 3 = +'23, T 4 = +'25. 



T, = +'43, T 2 = +'54, T S = +-05, T 4 = +-11. 



The volumes are in cubic centimetres and the temperatures are in Centigrade 

 degrees, reckoned from 11. 



The Reductions. 



The simple theory has already been given, but the actual reductions are rather 

 troublesome, on account of the numerous temperature corrections. These, however, 

 are but small. 



We have first to deal with the expansion of the mercury and of the iron in the 

 manometers. If the actual heights of the mercury (at the same temperature) be 

 H,, H 8 , we have for the relative pressures H/(l +nw), where m = '00017. Thus in 

 the notation already employed 



p 



l+THT/ l+mTj' 



and 



P = H) + H 2 or Hi+H 2 



The quantity of gas at a given pressure occupying a known volume is to be found 

 by dividing the volume by the absolute temperature. Hence each volume is to be 

 divided by 1+/30, 1 + $T, 1 -f/fr, as the case may be, where ft is the reciprocal of the 

 absolute temperature chosen as a standard for the set. Thus in the alx>ve example 



for hydrogen, /? = 



273 + 11 284' 



VOL. OCIV. A. 3 A 



