( :^fi5 ) 



nciglil)()iirli()()<I (tl" ils lops passos round jli(> lop ol' lli(> plait iii a 

 laii-ly \vi(le ciirle, so (hal it also eiicoiiipasscs llic |>lailp.oiiil. Wc 

 know about the ciirvo of the [)oiiits /.)aii(l />', oi- the poiiils lor whicli 



— - ^ (), lliat its lop li(^s insi(k^ iho plail. As to (he new locus 

 dv' 



ir,y =r: 0, which lies bctwecMi them, wo do iiol know a priori lio\v 



its top is siliia((Ml with regard to the toj) of the |)lail. We may oiil^- 



ox])ecl, liiat when tliere is a great distance between the fops of the 



plail and those of the points j'^.y^O, there is a greater chance tliat 



also the locus 1^,^- := i) will j)asy round the i)lait. Vov the j)lailpoint 



of tig. 7 the latter case has then be realized. For the |dailpoint of 



(ig. 8 ])robably the opposite case. 



For the poiids, for which ]^gj=={), wo get: 



or 



IT), \dT r r 



We might immediately have come to this conclusion. For from : 



0/) Ö'lf' 



follows the al)ove relation, keepini»' ,/■ constant, and -- or - — beini>' zei'o. 



r I 4^,1 ^t('':^ +<^--'>" 



If we write : 



cITj,^. \OTjr,, ' F,/- 



and now take inio considtM'ation that (?>/■),- is negalixc, we deri\e: 



w lieji I",/- is negative and \ice versa. 



I • . rr 'h' 



It we compare the value ot / ^- Un- the three-pliase-|u-ossure in 



<IT 



the inimediale neighboui-hood of a plailpoint. willi llic Naluc of 



7 1 — 1 lor the (Mpiijibriuiu of solid and lliiid phases in the next 



poiul, il may be dcmonsli-aled in sexci-al \\ays, thai lliose (pianlilies 

 ha\-e the same \alue. In lig. 7 il has been really rcpi-eseiiled like 

 Ihis, bul in liu'. S wo see in the iiejuboiirhood of /-* a sudden break 

 in the direclion of ihe |>ressure, which does not exist in realily. 



