803 



1 1 /T 4rr 



— ^^aV -^ ~ ^-a I I >/ {.(■, — .Vr, !/^—!h, -- — ~r) cos -^ {z^ — z-) d.v, . . . dt/r 



V V 



liX 



For a great volume one integration over V can he performed 

 (compare the deduction of formula (11)); further we put (iVz=zN 



4rt 



and for the sake of bre\itj — - cos \(f ^= C, then we get 



1 — 



- ^r N 



1 + jjfcos Cz g {.c, y, z) d.cdydzA ... (13) 



The integral appearing here will he represented l)v Gv, that of 

 formula (li) hy (t. It will be seen that the deductions criticised in 

 § 1 yield an opalescence proportional lo r-, a quantity which accord- 

 ing to the above is proportiojial to 1 -}- G, whereas the opalescence 

 is proportional to 1 -\- G,- 



With the aid of the integral-equation (B) we can express (t and 

 G,: in the corresponding integrals of the function ƒ. which we will 

 indicate by F and F,. 



Integrating (6) with resp. to .vyz from — oc to -|- oo. we tind 



JJJ'j'<-'y') ^"^'^y^' -jjjtl{^^l^)'l'idHdC,jJjjlv.^l;,-\-,l,Z H)dxdl,dz = 



+ 00 



ƒ {xyz) dndydz 



or 



G 



(14) 



1—/' 



Multiplying (6) by cos Cz and again integrating, we get 



-|- CO -j" ^ 



Or — i ii'Ahi^) dldnd^i ^ ^\cos C (.-4-?) COS C7S+ sin C {z -\-C) sin Cgj 



ƒ(.« + §, .'/ + >2, ^~+?) d.cdydz = F,. 

 The integral with the sines disappears because ƒ and </ are even 

 functions; we find 



G,.= 



Fr. 



\-F. 



(1 



In order to apply the results ol)tiiined and to lest them experi- 

 mentally, one might try to deduce ƒ from molecular theory. This 

 would at best be possible under very simplifying suppositions and 



