596 



As 



3 



2^ , > 



„/„, \ (-8 ^ _S„ 4_ 1 -«3 ) 



we get 



f=^ü^. • ■ • '«> 



Then we place the nu,i molecules: 



At the disposal of the first molecule are 



i ^ ) 



H 1 — riia-—) places, 



where a term with ^ has been omitted, being Jiegligible for the 

 order of magnitude wanted ; 



of the 2"*^^ molecule : 



here we must take into consideration that of the space at the 

 disposal of this molecule in the mean a certain part is occupied 

 bj one of the iim molecules; doing this we find for the number of 

 places at the disposal of the 2"^ molecule: 



X '- ^ 1—7/1^ —ï-^^ '-1?^±2\ places; 



di\ ( dv^ ) 



of the 3'*^ molecule : 



i 6 ) 



X 1 — (nia + 2) — places, 

 I ^" 1 1 



etc. 



Thus the placing of all the uih molecules (comp. Suppl. Leiden 

 N". 24A § 5) gives us the factor: 



/ dvA I dvA 



2— r^ 1/ 



(7) 



ni6i n\b\\ 





dv, J i dv. 



Now we are going to place the nici23 detinitelj fixed molecules, 

 belonging to sets of three, with the mutual distances 1\ {(Ir^), 1\ (dr,), 



rj((/r,). In — - — '- ways these molecules can be combined to such 



/ "lcl23 A 



sets, where it has been taken into consideration that 3 fixed molecules 

 can form such a set in 3! different ways viz. J «^ v^^irh distance from 

 molecule 1 to molecule 2 = ?-,, distance 2 to 3 = r,, distance 

 1 to 3 = 7-3; 2"'Ulislauce 1 to 2 = ?\, distance 2 to 3 - r,, distance 

 1 to 3 ?■ ; etc. 



