J 290 



il) which '/cL>, aiul </co, are two elements of space the distance of 

 which is expressed I)}- i\^, and in which the density of the niole- 

 cnles amounts respectively to ;i, and n^. We now can pnt: 



w, -rr ?« 4- A, + «',(7/ -I- A,) 

 ", = « -h ^, f '",(w + A,). 



1m tliis // represents the mean density, L the deviation, as we 

 might expect it also without cni'rent, ?(;, ?i, 3= ui^ {n -f- \7,) representing 

 according- to § 4 the deviation from the mean density brought about 

 hv the current. Terms that would contain //•^ have been neglected. 

 In the product n^n.^ the term (?i -|- A,) (n -|- Aj will yield the same 

 value for all the coordinate directions. This term would also occur 

 when there was no current, and its ijilegral in e(|ualioM f21) will 



a 



produce the term of the hydrostatic pressure according to the 



equation of state. Let us also remark that ?/A,=() and ??A,=rO, 

 iheu (2J) may he written as follows: 



V-:i—P = — 1 1 ^ ^- *-! {w^n^L^ -\- ic^n^L, f n^u\n,w,)dir^duij (21a) 



J J or,, r,. 



We shall neglect the third term. The \^^ and ilie 2'"' will he 

 equal on an average, hence we may lake twice the lirst. We shall 

 substitute in it the value for »;, that we have found in e(|ualion 

 (17), in which we may replace n' by A', because when A' is every- 

 where zero, also u\ becomes =r 0. Thus we find: 



vd^ a rrrr \ ,,ö'/'(^-$'r-(;-5r 



1 Or/. (.^-5j 



(loi'dxo doi^dio^ (21^) 



and iu the same way : 



p^^-p-- -df k^dj.y'^^^^ ^ -^ — 



kffjh 



1 dr/)(?,-c,r 



r, dr,, r, 



doi'do) dio. dvj. 



It will hardly be possible 10 calculate the value of these expres- 

 sions accurately. I shall confine myself to a rough estimation of the 

 order of magnitude, and demonstrate that />.-; — /> and P;r:-~p 

 assume equal but opposed values, which in virtue of the properties 

 of the stress tension had to be the case. 



