( 543 ) 



Measurement of the volnme : 



In order to jii(l,u<' of llic acciiracv we shall proceed as if we 

 had lo consider a (luaiililv of ,i;as incastircd in the UrsI lai'iic hull) 

 hjh^, above (sec 1. c. |)lalo 11 liu'. 1). 'IMicrc the ivlalive error is 

 lar.u'cst as the small liidl» /'7>., al»()\(^ is oidv used for aiixiliai'v 

 iiieasiireiuents. The calhetomeler used cei'taiiily reads well a( 0.04 mm. ; 

 lei the error he ().()2 mm. With a horr nï Eh. of ahoiit 200 mm'. 



this gives an erroi' of 4 mm'; on 250 cc. : . 



GOOOO 



The height of the nHM'Curv meniscus read in the Noliimciiometer \\as on 



an averaf!,'e 0.140 cm. I ha\-e supposed that the xolunie of the m(M-cur\ 



Ö 



meniscus is found bv mulliplvinj^' the bore bv — of the hei.uiil. The 



mean licigiil undonbledlv lies between the half and the whole height (cf. 



vScii.M.Kwi.iK ('oinm. N". (i7, These Pi'oc. Ill Jan. 1001 |). 488), so that the 



1 . . 1 



eri'or is certaiidv smaller than -~ ol the heiühl, sav — . Hence this 



4 ^ * 8 



gives — X^'i^^ mm. =0.18 mm., on the \()lnme an ei"i-or of 



o 



1 1 



36 mm" or . In order lo reach an accuracv of a 



7000 • 10000 



moi-e detailed investigation of th(> xolnmes of the mercnrv menisci 



at this i-adins (7.8 mm.) would be recpured, in the wav as ScitAi.KWi.iK 



I.e. has done for radii from 0.5 to 4 mm. 



The vai'iation of the volume due to temperature can accurately 

 be acconiited for. 



Variation of volume owing to diftei-ence of pressure in and outside 

 the volumenometer. 



If we a\ail oursehes of the circumstance that the thickness of the 

 wall is small as com[)ai'ed with the radius, a calculation aj)plied to 

 each bulb in(li\iduall_v gives: 



'Y ~ 1 E d 



1 



or for our case, [)utling: y^zzrüöOO K.G./mm.', f< = -— -, with A'=:39 



mm., d = 0.5 mm.: 



(fV 



— — 0.00000177 ipi—pe) 



if /)(■ and p,. are expressed in centimeters of mercnrv; so that for 



rf^ 1 T. I- 



n: — o,, =3 ob cm.: — ==: — . l' Ol' this a coi'reetion is aitplied 



^ ^' V 10000 '* 



