( 413 ) 



\ï wo iiitrodiKM! litis value ol' if' in e(|ii;xlioii (8) we get 



3 



o 1-23' 



which is eiilii'elv coiisisleiil \\'\\\\ Ihe (hMihle proporlioii. 



Conseqneiitlii it = 6 is the oiilij otitic > 5 ilutt is consish'nl ti-illt 

 the principle of the rittioiial iitt/ircs. If we extend (he re(jiiireiueiit 

 that cos xp must be mtioiial to the ease it <^ 5 then tlie values ii = '2, 

 3, 4, are also [)ennissil)le (or axes of the (irst kind, and the \alues 

 n=2, 4 for axes of (he secoiid kind. 



(rö/fiio/cit, November l'.K)7. 



Physics. -- '" Isollicfiits of <liitloiiitc (jiisi's iiitil ï/tt'if /)iii(f!-i/ itti.ritirrs. 

 \\. Isotloiitis of hinh'iujni^ Ix^ltrceit — J()4"C. niid —21T Vr 

 (Continued). l)j Pj'of. 11. Kaahiklixcmi ( )nnes and C. Uraak. 

 Communication N". JOO' from (he Physical Lal)ora(ory at 

 Leiden. 



(Communicated in (lie mccling of Novemljer 30, 1007). 



§ 17. S/tiT(>i/ of the (h'tcrirtiiKitiotis. Ri' tit (irk oit tin' <ti>j)tir(itiis. 



The nicasuremejds men(ione(l in this (,\)mmunica(ion comprise in 

 the (irst place the supplementary determinations to which we already 

 alluded in § 14 of Comni. N". 99" (Sept. 1907). These are three 

 detenninatiojis at — 217° at a density of about 170 times the normal one. 



The ol)vious thing to do further was to rei)eat the other dcterminatioiis 

 of series II with the same piezometer arranged for the determinations 

 mentioned aboxe, this piezometer being one of about the same 

 dimensiojis as that of series II of Comm. N". 97" (lAIarch 1907). 

 As a matter of fact a comparison of the values of pvx ol)tained in 

 this series with those yielded by the series III and IV^ teaches that 

 the former lie somewhat, though only slightly, lower than the latter. 

 This may be due to a systematical error as the filling in the later 

 series was accomplished with more [)recautions (compare § 5 of 

 Comm. W. 97"). In the sei'ies now given, just as in series IV, distilled 

 hydrogen was used. 



Both the steel tubes on the stem of the piezometer and those on 

 the stem of the piezometer reservoir ^vere soldered to the glass (cf. 

 § 15 of Comm. N". 99"). This ensures a gas-proof connection with 

 the steel ca])illary. Willi sealing w^ax it is difficult to make the 

 connection gas-proof, because sometimes the nut begins to slide off 

 when the llange is lightly screwed on. 



