measured al ahoiil 20'' (' iIm' llicorclical iioniial vctlnmc of tlial 

 (|iiantit} of u-as (al ü" (Jj. 



Physics. — ''■Jsotlwrniiils of n/i.rfnrrs of ii.ri/t/f'// mid cnrJnni (luKCuh'. 

 lil. The (I('frfiii/ii>i/i()i/ of isolhcriiKils hrdri't'ii 1)0 iind 140 

 (itiiiosithciu's, mul hrlii'f'i'ii — 15 (_' diid -}-()0"^'." By W . II. 

 Kkksom. (Vniiiuiinicalioii X". .S8 (3''^ |)ai'l) IVoin tlic PliAsical 

 Laboi-alory at Leiden, hy Pi-of. 11. Kamkri,in(;ii Onnes. 



((Joinniunicated in the niooling uf Ücloljer 31, 11)03). 



§ 1. Diiriiiu' my nieasiiremeiils of llie isotliei-iuals of inixtnres of 

 oxviiX'ii and caflxiii dioxide il a|)i)eared desiraltle to lake se\ei'al 

 precaution"^ and lo make some modilicalioiis in llic nsnal nielliods. 

 Tliey will he (lesei'ii)ed lier(^ in eonneelion willi and in behalf of 

 following!: |>apers on the i*esulls obtained. 



§ 2. lli>' tirfii/ii/rii/(U/f. The inanomelertid)e and the expei-imental 

 lidx; which befoi'ehand had beeji cenienlcd into a steel thmued lid»c 

 (conip. Comni. X". 70 V, These Proc. \\ Jnne 29, '01 ]). 107) were 

 placed into steel jn-essnre cylin(hM-s. For the sha|>es of these see also 

 Comni. X°. 43, Th(>sc Proc. 1 June 25, IcSiJH, j.. 83, tig. 2. The 

 arrangement as drawn there has been modilied, \i/. the two pressure 

 cylinders into \\ hich the aforementioned tnbes were placed were 

 entii-ely filled with mercury. They coninnmicated at Iheir lower einls 

 by means of a steel tube and of a steel T-piece with each other and 

 with a thii'd pressure cylinder. This was tilled partly with mercury 

 partly with glycci'ine. To ol)tain pressni-e, glycerine was forced into 

 it by means of a S( iiAFFEK-BrDKNBF.iu; j>ump. This arrangement oifei-s 

 the advantage thai the tubes tilled \Nilh gas do nol come into contact 

 with the glycerine, and the mercury which is forced into the tnbes 

 only slightly with the glycerine. In this way it was vovy easy to 

 redeternnne the normal xolume aflei- lifliiiü' oul the experimental tube 

 from the pre.ssure cylinder, Avhile the mercury menisci in the lubes 



